Conference Highlights - Advances in Antiretroviral Therapy Volume 15 Issue 2 April/May 2007

Advances in Antiretroviral Therapy Joyce Jones, MD, Barbara Taylor, MD, Timothy J. Wilkin, MD, MPH, and Scott M. Hammer, MD

The 14th Conference on Retroviruses and Opportunistic provided line HIV-1 RNA of 4.8 to 4.9 log10 cop- a forum for presentation of state-of-the-art research on antiretroviral ies/mL. The primary endpoint, a reduc- therapy. This year’s conference marked the first public presentation of tion in plasma HIV-1 RNA at 24 weeks, phase III trials of the lead compounds in 2 new drug classes: (a was statistically significantly greater in

CCR5 inhibitor) and (an HIV-1 ). These agents the once-daily (1.82 log10 copies/mL) are likely to be approved by the US Food and Drug Administration this and twice-daily arms (1.95 log10 cop- year and should provide major new options for treatment-experienced ies/mL) than in the placebo arm (1.03 patients with multidrug resistant virus. Other dominant themes of the log10 copies/mL). Subjects in the once- conference were the impressive number of presentations describing and twice-daily arms were more likely outcomes of antiretroviral therapy programs in resource-limited settings to achieve plasma HIV-1 RNA levels and new information on mechanisms of drug resistance. Among the latter, below 50 copies/mL at week 24 than the importance of drug resistance mutations occurring in the RNase H and subjects in the placebo arm (42% and connection domains of the HIV-1 was of special note. 49% vs 25%, respectively), and had a In addition, substantial new information was presented on other new greater increase in CD4+ counts (107 antiretroviral agents, studies in treatment-naive patients, antiretroviral and 111 vs 52 cells/µL, respectively). therapy strategies, prevention of mother-to-child transmission, predictors There were no marked safety issues of clinical response to therapy, and antiretroviral pharmacokinetics. and the rates of adverse events in the Research in antiretroviral therapy remains dynamic and advances in the maraviroc arm were not statistically field continue to improve our ability to maintain long-term control of significantly different from rates in the HIV-1 replication in infected persons. placebo arm, including liver-related adverse events and malignancies. New Antiretrovirals Antiretrovirals in Late-phase In MOTIVATE 2, 464 subjects were Clinical Development enrolled (approximately 85% of sub- A major focus of this year’s conference jects were white and 84% were male). was the presentation of phase III stud- Entry Inhibitors: Maraviroc. Outcomes Across groups the median ranges were ies of entry and integrase inhibitors, of 2 phase IIb/III studies of maravi- baseline CD4+ counts of 174 to 182 which showed good clinical outcomes roc, an investigational CCR5 inhibitor, cells/µL and baseline HIV-1 RNA of 4.8 with acceptable side effect profiles. were presented: MOTIVATE 1 (Abstract to 4.9 log10 copies/mL. The primary (see Table 1) These drugs are likely to 104aLB) and MOTIVATE 2 (Abstract endpoint, reduction in plasma HIV- be approved by the US Food and Drug 104bLB). The studies were of identical 1 RNA at 24 weeks, was significantly

Administration (FDA) in 2007 and will design but conducted in different coun- greater in once-daily (1.95 log10 copies/ provide new options for treatment-ex- tries. Eligible subjects were 3-class ex- mL) and twice-daily arms (1.97 log10 perienced patients with multidrug re- perienced patients with plasma HIV-1 copies/mL) than in the placebo arm sistant HIV-1. Studies on antiretrovirals RNA levels above 5000 copies/mL and (0.93 log10 copies/mL). Subjects in the in early-phase and preclinical develop- exclusive use of CCR5 coreceptor for once- and twice-daily arms were more ment highlighted promising drugs that entry as determined by tropism testing. likely to achieve a plasma HIV-1 RNA will hopefully further expand antiret- Subjects were randomized 1:2:2 to pla- level below 50 copies/mL at week 24 roviral regimens available to HIV-sero- cebo, maraviroc 150 mg once daily, and than subjects in the placebo arm (41% positive patients. maraviroc 150 mg twice daily, all given and 46% vs 21%, respectively), and with an optimized background regimen had a greater increase in CD4+ count (OBR) of 3 to 6 antiretrovirals. If subjects (112 and 102 vs 64 cells/µL, respective- Dr Jones is an Instructor of Clinical Medi- were not receiving a -boosted ly). There were no marked safety is- cine at Columbia University Medical Center. protease inhibitor (PI), they received sues and rates of adverse events in the Dr Wilkin is an Assistant Professor of Medi- maraviroc 300 mg once or twice daily. maraviroc arm were not statistically cine at Weill Medical College of Cornell Both studies had similar participant significantly different from rates in the University. Dr Taylor is a Fellow at Columbia baseline characteristics. University Medical Center, New York Pres- placebo arm, including liver-related byterian Hospital. Dr Hammer is Professor In MOTIVATE 1, 585 subjects were en- adverse events and malignancies. of Medicine at the Columbia University Col- rolled (approximately 82% were white The combined analysis from these 2 lege of Physicians and Surgeons and Chief and 90% were male). Across groups the trials showed that 56% of subjects who of the Division of Infectious Diseases at Co- median ranges were baseline CD4+ screened for this study had HIV-1 that lumbia Presbyterian Medical Center. counts of 150 to 168 cells/µL and base- utilized only the CCR5 coreceptor for

48 International AIDS Society–USA Topics in HIV Medicine

Table 1. Selected Trials of Investigational Antiretroviral Drugs in Treatment-experienced Patients

Study Name Regimen(s) Population Baseline CD4+ Log10 Copies HIV Follow-up HIV-1 RNA Response Comments Abstract No. (No. Patients) cells/μL RNA/mL Time Description

MOTIVATE-1 Best available regimen 3-class experienced; plasma 150-168 (median) 4.8-4.9 (mean) 24 weeks –1.03 vs –1.82 and –1.95 log10 Abstract 104aLB (PIs, nRTIs, +/– ) HIV-1 RNA >5000 copies/ copies/mL (n=118) mL; CCR5-using virus Phase IIb/III randomized, double- 25% vs 42% and 49% <50 vs blind trial of maraviroc, an copies/mL Combined analyses: investigational CCR5 inhibitor maraviroc 150 mg qd (n=232) or maraviroc 150 The qd and bid dosing groups mg bid (n=235) appeared no different when having 1 or more active drugs in OBR; in

MOTIVATE-2 Best available regimen 1 or more major PI 174-182 (median) 4.8-4.9 (mean) 24 weeks –0.93 vs –1.95 and –1.97 log10 31/49 subjects in whom maraviroc Abstract 104bLB (PIs, nRTIs +/– enfuvirtide) mutations, 3-class copies/mL failed, there was a change in (n=91) experience coreceptor usage Phase IIb/III randomized, double- 21% vs 46% and 41% <50 vs blind trial of maraviroc copies/mL maraviroc 150 mg qd (n=182) or maraviroc 150 mg bid (n=191)

BENCHMRK-1 Raltegravir 400 mg bid Genotypic or phenotypic 153-156 (mean) 4.5-4.6 (mean) 16 weeks 77% vs 41% <400 copies/mL Abstract 105aLB (n=232) resistance to at least 1 drug 61% vs 33% <50 copies/mL or from all 3 current classes, Phase III, randomized, placebo- plasma HIV-1 RNA >1000 Combined analyses: controlled trial of raltegravir placebo with OBR (n=118) copies/mL 32/41 subjects in whom raltegravir (MK0518), an investigational failed had mutations in integrase; integrase inhibitor 98% of subjects receiving raltegravir and enfuvirtide for the BENCHMRK-2 Raltegravir 400 mg bid Genotypic or phenotypic 146-163 (mean) 4.5-4.6 (mean) 16 weeks 77% vs 43% <400 copies/mL first time had <400 HIV-1 RNA Abstract 105bLB (n=230) evidence of resistance to 62% vs 36% <50 copies/mL copies/mL at week 16 or at least 1 drug from all 3 Phase III, randomized, placebo- placebo with OBR (n=119) current classes, plasma HIV-1 controlled trial of raltegravir RNA >1000 copies/mL

The HIV Integrase Inhibitor (20 mg, 50 mg, 1 or more PI mutations, 157-243 (median) 4.5-4.7 (median) 16 weeks 50-mg arm, –1.5 log10 copies/mL GS-9137 Demonstrates Potent or 125 mg) + ritonavir 100 plasma HIV-1 RNA >1000 Elvitegravir led to rapid declines in 125-mg arm, –1.7 log10 copies/mL ARV Activity in Treatment- mg qd or best available copies/mL plasma HIV-1 RNA at week 2 that vs experienced Patients control PI given with OBR were sustained only if there were

Abstract 143LB (n=278) control arm, –1.2 log10 copies/mL other active drugs in the OBR Phase II, dose-finding study 20-mg arm stopped early for of elvitegravir (GS9137), an virologic failure investigational integrase inhibitor

PI indicates protease inhibitor; nRTI, reverse transcriptase inhibitor; OBR, optimized background regimen; qd, once-daily; bid, twice daily. entry (R5 HIV). Eight percent of subjects tive drugs in the OBR was found to be a in the OBR, indicating that difference in who had R5 HIV at screening had dual predictor of suppression to less than 50 viral load outcomes between once- and or mixed HIV-1 populations that utilized HIV-1 RNA copies/mL and baseline HIV-1 twice-daily maraviroc was apparent only both CCR5 and CXCR4 coreceptors for RNA viral load was not related. The pro- among patients with no active drugs in entry at baseline, prior to receiving mara- portion of patients achieving HIV-1 RNA the OBR. viroc. The dual or mixed HIV subjects below 50 copies/mL in the once- and Among patients with virologic fail- who received maraviroc had a poorer twice-daily arms were 18% and 29%, re- ure, change in coreceptor usage from virologic response than R5 HIV subjects spectively, among patients with no active R5 HIV to dual or mixed HIV was noted who received maraviroc. These results are drugs in the OBR; 43% and 43% with 1 in 4 of 84 (5%) subjects in the placebo similar to what was observed in a previ- active drug in the OBR; 52% and 53% groups, 31 of 49 (63%) subjects in the ously presented trial of maraviroc in dual with 2 active drugs in the OBR; and 61% once-daily groups, and 32 of 49 (65%) or mixed HIV subjects. The number of ac- and 58% with 3 or more active drugs of subjects in the twice-daily groups. 49 Conference Highlights - Advances in Antiretroviral Therapy Volume 15 Issue 2 April/May 2007

Table 1. Selected Trials of Investigational Antiretroviral Drugs in Treatment-experienced Patients the median ranges were baseline CD4+ counts of 153 to 156 cells/µL

Study Name Regimen(s) Population Baseline CD4+ Log10 Copies HIV Follow-up HIV-1 RNA Response Comments and baseline HIV-1 RNA of 4.5 to 4.6 (No. Patients) cells/μL RNA/mL Time Abstract No. log10 copies/mL. The OBR contained Description 0 or 1 active drug in 48% to 51% of subjects; 20% to 21% received enfu-

MOTIVATE-1 Best available regimen 3-class experienced; plasma 150-168 (median) 4.8-4.9 (mean) 24 weeks –1.03 vs –1.82 and –1.95 log10 virtide for the first time and 25% to Abstract 104aLB (PIs, nRTIs, +/– enfuvirtide) HIV-1 RNA >5000 copies/ copies/mL 27% received for the first (n=118) mL; CCR5-using virus Phase IIb/III randomized, double- 25% vs 42% and 49% <50 time. More subjects in the raltegravir vs blind trial of maraviroc, an copies/mL group achieved plasma HIV-1 RNA lev- Combined analyses: investigational CCR5 inhibitor maraviroc 150 mg qd els below 400 copies/mL (77%) and (n=232) or maraviroc 150 The qd and bid dosing groups below 50 copies/mL (61%) at week mg bid (n=235) appeared no different when having 16 than subjects in the placebo group 1 or more active drugs in OBR; in (41% and 33%, respectively). Subjects MOTIVATE-2 Best available regimen 1 or more major PI 174-182 (median) 4.8-4.9 (mean) 24 weeks –0.93 vs –1.95 and –1.97 log 31/49 subjects in whom maraviroc 10 receiving raltegravir had a greater in- Abstract 104bLB (PIs, nRTIs +/– enfuvirtide) mutations, 3-class copies/mL failed, there was a change in (n=91) experience coreceptor usage crease in CD4+ count than those in Phase IIb/III randomized, double- 21% vs 46% and 41% <50 vs the placebo group (83 cells/µL vs 31 blind trial of maraviroc copies/mL maraviroc 150 mg qd (n=182) cells/µL). or maraviroc 150 mg bid Similar results were observed in (n=191) BENCHMRK-2 (Abstract 105bLB). Of the 349 subjects enrolled, approxi- BENCHMRK-1 Raltegravir 400 mg bid Genotypic or phenotypic 153-156 (mean) 4.5-4.6 (mean) 16 weeks 77% vs 41% <400 copies/mL mately 60% were white and 90% were Abstract 105aLB (n=232) resistance to at least 1 drug 61% vs 33% <50 copies/mL male. Across groups the median ranges or from all 3 current classes, were baseline CD4+ counts of 146 to Phase III, randomized, placebo- plasma HIV-1 RNA >1000 Combined analyses: controlled trial of raltegravir placebo with OBR (n=118) 163 cells/µL and baseline HIV-1 RNA copies/mL 32/41 subjects in whom raltegravir (MK0518), an investigational of 4.5 to 4.6 log10 copies/mL. The OBR failed had mutations in integrase; integrase inhibitor contained 0 or 1 active drug in 44% to 98% of subjects receiving 46% of subjects. Nineteen percent to raltegravir and enfuvirtide for the BENCHMRK-2 Raltegravir 400 mg bid Genotypic or phenotypic 146-163 (mean) 4.5-4.6 (mean) 16 weeks 77% vs 43% <400 copies/mL first time had <400 HIV-1 RNA 20% received enfuvirtide for the first Abstract 105bLB (n=230) evidence of resistance to 62% vs 36% <50 copies/mL copies/mL at week 16 time and 45% to 50% received daruna- or at least 1 drug from all 3 vir for the first time. More subjects in Phase III, randomized, placebo- current classes, plasma HIV-1 controlled trial of raltegravir placebo with OBR (n=119) the raltegravir group achieved plasma RNA >1000 copies/mL HIV-1 RNA levels below 400 copies/mL (77%) and below 50 copies/mL (62%) The HIV Integrase Inhibitor Elvitegravir (20 mg, 50 mg, 1 or more PI mutations, 157-243 (median) 4.5-4.7 (median) 16 weeks 50-mg arm, –1.5 log copies/mL 10 at week 16 than did subjects in the pla- GS-9137 Demonstrates Potent or 125 mg) + ritonavir 100 plasma HIV-1 RNA >1000 125-mg arm, –1.7 log copies/mL Elvitegravir led to rapid declines in 10 cebo group (43% and 32%, respective- ARV Activity in Treatment- mg qd or best available copies/mL plasma HIV-1 RNA at week 2 that vs experienced Patients control PI given with OBR were sustained only if there were ly). Subjects receiving raltegravir had a greater increase in CD4+ count than Abstract 143LB (n=278) control arm, –1.2 log10 copies/mL other active drugs in the OBR those in the placebo group (86 cells/µL 20-mg arm stopped early for Phase II, dose-finding study vs 40 cells/µL). of elvitegravir (GS9137), an virologic failure The authors presented data on com- investigational integrase inhibitor bined analysis of both studies. Geno- typic resistance data were available for PI indicates protease inhibitor; nRTI, nucleoside analogue reverse transcriptase inhibitor; OBR, optimized background regimen; qd, once-daily; bid, twice daily. 41 subjects who had virologic failure while receiving raltegravir. Thirty-two of There were no obvious adverse effects 105bLB). The 2 studies were identical in 41 had resistance-associated mutations that resulted from change in coreceptor design. Inclusion criteria included evi- in integrase, and mutations fell gener- usage. CD4+ cell counts were generally dence of genotypic or phenotypic resis- ally into one of 2 mutational pathways: well preserved in subjects who experi- tance to at least 1 drug from each of 3 N155H or Q148K/R/H. One of these enced change in coreceptor usage. classes and plasma HIV-1 RNA levels of mutations was usually present with above 1000 copies/mL. Subjects were additional integrase mutations. These Integrase Inhibitors: Raltegravir and randomized 2:1 to raltegravir 400 mg pathways were expected based on in GS-9137. Investigators presented data twice daily or placebo in each study. vitro data. Subgroup analysis showed from 2 phase III studies of the inves- In BENCHMRK-1 (Abstract 105aLB), that 98% of subjects receiving raltegra- tigational HIV-1 integrase inhibitor 350 subjects were enrolled (approxi- vir with de novo use of both enfuvirtide raltegravir (MK-0518), BENCHMRK-1 mately 78% of subjects were white and darunavir achieved HIV-1 RNA lev- and BENCHMRK-2 (Abstracts 105aLB, and 85% were male). Across groups els below 400 copies/mL at 16 weeks, 50 International AIDS Society–USA Topics in HIV Medicine

and 90% of subjects receiving ralte- sine ([±]-FTC) Pozniak and colleagues jects with less than 3 thymidine ana- gravir with de novo use of either enfu- (Abstract 144LB) presented data from logue mutations (TAMs) accounted for virtide or darunavir achieved HIV-1 RNA the TMC278-C204 trial, a phase IIb the majority of the benefit (reduction levels below 400 copies/mL at week 16. study of an investigational non-nucle- of 0.7 log10 copies/mL). No obvious The overall rate of serious drug-related oside reverse transcriptase inhibitor safety issues were noted. adverse events was low in both studies (NNRTI) with retained antiviral activity and no specific adverse events were as- against HIV and resistant to currently Antiretrovirals in Phase I and sociated with raltegravir use. FDA-approved NNRTIs, in treatment- Preclinical Development Zolopa and colleagues (Abstract naive subjects. Subjects were random- 143LB) presented data from a phase II ized to 1 of 3 doses of or Nucleoside Reverse Transcriptase In- dose-finding study of the investigation- once daily, given with fixed- hibitors: IDX12899 and IDX12989. al integrase inhibitor GS-9137. Eligible dose tenofovir/ or zidovu- Richman and colleagues (Abstract 489) subjects had plasma HIV-1 RNA levels dine/. The median baseline presented data on 2 investigational above 1000 copies/mL and 1 or more plasma HIV-1 RNA was 4.9 log10 cop- NNRTIs: IDX12899 and IDX12989. PI mutations. There were 278 subjects ies/mL and the median CD4+ count Both compounds exhibited potent ac- randomized to 1 of 3 doses of GS-9137 was 203 cells/µL. Three hundred sixty- tivity against a broad range of clinical (20 mg, 50 mg, or 125 mg with 100 eight subjects (33% women and 53%- isolates including isolates with single- mg ritonavir once daily) or best avail- 56% nonwhite) were randomized. In and double-NNRTI mutations. The able PI. The subjects were 90% male an intention-to-treat analysis, 77% pharmacokinetic profiles in various and 73% white, and 23% used enfu- to 81% of subjects in the rilpivirine animal models supported once-daily virtide for the first time. The median arms achieved the primary endpoint dosing. No adverse events were noted baseline CD4+ count was 157 to 243 of below 50 HIV-1 RNA copies/mL in acute toxicology models. Serial pas- cells/µL and mean baseline HIV-1 RNA compared with 81% in the efavirenz sage studies exhibited a longer time level was 4.5 to 4.7 log10 copies/mL. arm, a difference that was not statis- for development of resistance to these The 20-mg arm was stopped early tically significant. Increases in CD4+ compounds than to efavirenz. due to inferior virologic performance. count were similar in both arms (123- Through 16 weeks, the control arm 145 cells/µL in the rilpivirine arms vs Protease Inhibitors: GS-8374. Callebaut had an average virologic reduction of 125 cells/µL in the efavirenz arm; P = and colleagues (Abstract 491) presented

1.2 log10 HIV-1 RNA copies/mL com- not significant). There were, however, data on a novel peptidomimetic PI, GS- pared with 1.5 log10 copies/mL in the better overall lipid profiles and signifi- 8374. In vitro studies showed potent

50-mg group and 1.7 log10 copies/mL cantly lower rates of rash and central activity against a range of clinical iso- in the 125-mg group. Although this nervous (CNS) system side effects in lates including those with resistance to was a noninferiority study design, the the rilpivirine arms than in the efavi- darunavir and . Development 125-mg group had a statistically signifi- renz arm. The rates of serious adverse of resistance to this compound did not cantly greater viral load reduction than events were low and there was not a occur after 6 months of serial passage the control group. Thirty-eight percent statistically significant difference be- experiments despite development of and 40% of subjects receiving the 2 tween groups. Complete resistance resistance to , , and higher doses achieved below 50 HIV-1 analysis is underway and was not darunavir in parallel experiments. GS- RNA copies/mL at week 16 compared available at this presentation. 8374 showed minimal effects on lipid with 30% of subjects in the control (±)-FTC is an investigational mix- accumulation and insulin-stimulated arm. Subjects with no active drugs in ture of emtricitabine plus its D-enan- glucose uptake in adipocytes. the OBR tended to have a rapid drop in tiomer. Cahn and colleagues (Abstract plasma HIV-1 RNA at week 2 followed 488) presented data on a double-blind, Integrase Inhibitors: MK-2048 and by virologic rebound, whereas subjects phase II trial of (±)-FTC in treatment- GSK364735. Wai and colleagues (Ab- with 1 or more active drugs in the OBR experienced subjects. Entry criteria stract 87) presented data on a new had more sustained virologic suppres- included current virologic failure on a series of compounds that inhibit the sion. Thus, GS-9137 was well tolerated lamivudine–containing regimen and strand transfer reaction of HIV inte- and no marked safety concerns were presence of the M184V mutation. Sub- grase and are similar to 2 integrase identified. This study highlights the im- jects were randomized to receive (±)- inhibitors in late-stage clinical devel- portance of supporting integrase inhib- FTC 600 mg and discontinue lamivu- opment (napthyridine [L-870810] and itor use with other active drugs in the dine (n=26) or continue lamivudine pyrimidinone [MK-0518, raltegravir]), regimen to avoid the rapid emergence (n=16) for 28 days. The lamivudine but were designed to have a higher of drug resistance to this new class. group had an increase in plasma HIV genetic barrier to resistance and lim-

RNA-1 of 0.13 log10 copies/mL com- ited cross-resistance to previously de-

New Reverse Transcriptase Inhibi- pared with a decrease of 0.4 log10 cop- scribed compounds. One compound, tors: Rilpivirine (TMC278) and (±)- ies/mL in the (±)-FTC group (P < .01). MK-2048, was found to have a 95% in-

ß-2', 3'-dideoxy-3'-thia-5-fluorocyto- Subgroup analysis showed that sub- hibitory concentration (IC95) of 41 nM 51 Conference Highlights - Advances in Antiretroviral Therapy Volume 15 Issue 2 April/May 2007

and a pharmacokinetic profile in dogs antisense oligonucleotide analogues that tiretroviral activity at an EC50 1.1µM in and rats that suggests once-daily dos- block complementary RNA sequences. HIV-1-infected macrophages. The 50% ing in humans is possible, and demon- Bestwick and colleagues (Abstract 499) cytotoxicity concentration was 212 µM, strated retained activity against HIV-1 investigated the potential for PMO to act suggesting a favorable antiviral index. It strains resistant to integrase inhibitors against the highly conserved start codon showed broad activity against a range of currently in clinical development. region of the HIV-1 vif gene and the Tar clinical isolates and appeared to be syn- Reddy and colleagues (Abstract 562) stem-loop. They found that the optimal ergistic with several antiretrovirals. presented data on the safety and phar- vif PMO generated was able to inhibit macokinetics of an HIV-1 integrase in- viral replication with a median effective Clinical Trials in hibitor, GSK-364735, in HIV-uninfected concentration (EC ) of 260 nM whereas 50 Treatment-naive Patients subjects. Among 79 subjects, they found the Tar stem-loop PMO inhibited with an only mild adverse events except for 1 EC50 of 3.6 µM. These data support pur- Trials in Treatment-naive Patients moderate headache. No grade 2 or high- suing this strategy for antiretroviral drug with Established HIV-1 er laboratory events were noted. Food development. increased the bioavailability of this com- Results of selected treatment trials in pound by 30% to 100%, and aluminum Histone Deacetylase Inhibitors. La- antiretroviral-naive patients are sum- and magnesium hydroxide decreased tently infected, resting memory CD4+ marized in Table 2. bioavailability by 50%. The compound T cells are a major reservoir for HIV and Mildvan and colleagues (Abstract did not markedly alter CYP450 enzymes represent a significant barrier to eradi- 138) presented results of the A5073 except for weak inhibition of CYP1A2 cation of HIV from infected individuals. trial, a 48-week, multicenter, 3-arm, and the pharmacokinetic profile was not Histone deacetylases (HDACs), of which open-label trial that compared lopina- affected by ritonavir. The pharmacoki- there are 3 classes (I, II, and III), are vir 400 mg/ritonavir 100 mg soft gel netic data supported twice-daily dosing important in maintaining viral latency capsule self-administered twice daily, in future phase II studies. by causing the DNA to become tightly lopinavir 800 mg/ritonavir 200 mg self- bound, thus preventing access to HIV administered once daily, and lopinavir CXCR4 Inhibitors: AMD11070. Two DNA by nuclear transcription factors. 800 mg/ritonavir 200 mg via directly studies evaluated AMD11070, an investi- HDAC inhibitors may lead to expression observed therapy once daily. Partici- gational oral CXCR4 inhibitor: the X4 An- of HIV genes resulting in productive in- pants were antiretroviral-naive with tagonist Concept Trial (XACT), presented fection, which would then expose the HIV-1 RNA levels above 3.3 log10 cop- by Moyle and colleagues (Abstract 511), previously latent HIV-infected cells to ies/mL and were randomized in a 2:2:1 and AIDS Clinical Trials Group (ACTG) immune surveillance and the effects of ratio stratified by screening HIV-1 RNA

A5210 presented by Saag and colleagues antiretroviral drugs. Valproic acid is a levels above or below 5.0 log10 cop- (Abstract 512). Both were phase I stud- known nonspecific HDAC inhibitor. Wei- ies/mL. All patients received emtric- ies that evaluated exposure to 10 days man and colleagues (Abstract 500) pre- itabine 200 mg with extended-release of AMD11070 given twice daily. Eligible sented data on several small molecules 100 mg or tenofovir 300 mg subjects were off antiretroviral therapy, that inhibit class I HDACs and showed once daily. The 402 patients enrolled had plasma HIV-1 RNA levels above that these molecules promoted histone had a baseline median CD4+ count 5000 copies/mL, and above 2000 rela- acetylation. Archin and colleagues (Ab- of 197 cells/µL and median HIV-1 RNA tive luminescence units (RLU) of CXCR4 stract 501) then tested these HDAC in- level of 4.8 log10 copies/mL. The differ- usage in the trofile assay. Nearly all sub- hibitors on latently infected CD4+ cells ence in plasma HIV-1 RNA at 48 weeks jects received 200 mg of AMD11070 and showed that they increased viral between the once- and twice- daily twice daily for 10 days. Four of 9 in XACT transcription and effectively withdrew groups was 0.03 log10 copies/mL (95% and 3 of 6 in ACTG 5210 subjects had at cells from latency. confidence interval [CI], −0.07-0.12). least a 1-log10 reduction in X4 RLU (indi- However, in the higher HIV-1 RNA level cating a decrease of plasma HIV–1-using Vpu Ion Channels. Vpu has been stratum, the probability of sustained CXCR4 for entry in CD4+ cells) after 10 shown to have 2 important functions in virologic response at 48 weeks was days of monotherapy. Both studies con- the lifecycle of HIV-1: virion assembly statistically significantly higher in the cluded that proof-of-concept has been and release, and CD4+ degradation. It twice-daily group than in the once-daily established and that further studies are associates in pentamers to form a cat- self-administered group (0.89; 95% CI, warranted. The clinical development of ion-specific ion channel. Luscombe and 0.79-0.94 vs 0.76; 95% CI, 0.64-0.84, AMD11070 has been put on hold due to colleagues (Abstract 502) presented data respectively). Probabilities of sustained abnormal liver histology in long-term on several inhibitors of the Vpu ion chan- virologic response at 24 and 48 weeks toxicology studies in animals. nel. Such inhibitors should be effective between the directly observed therapy at interfering with viral replication in and once-daily self-administered arms Morphilino Antisense Oligonucle- macrophages, a reservoir not targeted were not statistically significantly dif- otides. Phosphorodiamidate morpho- by currently available drugs. The lead ferent. lino oligomers (PMOs) are water-soluble compound, BIT225, showed potent an- Rey and colleagues (Abstract 503)

52 International AIDS Society–USA Topics in HIV Medicine

presented the preliminary results of compared with 17 (6%) in the abaca- Trials in Treatment-naive Patients the DAUFIN study, a randomized, vir arm (P = .06). A similar trend was with Acute HIV-1 Infection open-label, multicenter, noninferiority observed for WHO stage III events, but trial of once-daily lamivudine 300 mg, was not statistically significant. Estes and colleagues (Abstract 67) ex- tenofovir 245 mg, and 400 Bussmann and colleagues (Abstract amined the impact of antiretroviral treat- mg versus twice-daily 300 507) presented preliminary results ment on CD4+ cell populations in lymph mg/lamivudine 150 mg and nevirap- from the Tshepo Study, an open-label, nodes, Peyer’s patches, and the lamina ine 200 mg. The trial was stopped by randomized, ongoing study in Botswa- propria by obtaining inguinal lymph the steering committee after 12-week na examining 3 different nucleoside node and ileum biopsies in 32 HIV-1-in- data showed 7 early nonresponses reverse transcriptase inhibitor (nRTI) fected and 11 HIV-seronegative individu- (defined as plasma HIV-1 RNA with a regimens, 2 NNRTI regimens, and als. They obtained follow-up biopsies in 15 of the HIV-1-infected individuals 6 less than 2.0 log10 copies/mL decrease community-based directly observed months after initiation of potent antiret- or rebound of more than 1.0 log10 cop- therapy versus standard of care. The ies/mL after initial decrease) in the study enrolled 650 antiretroviral-naive roviral therapy. All compartments were once-daily arm and no early nonre- patients between December 2002 and significantly depleted of CD4+ cells in sponses in the twice-daily arm. The December 2004. Sixty-nine percent of HIV-1-infected patients and, after initia- early nonresponders had higher base- the patients were female and baseline tion of antiretroviral therapy, there was line median plasma HIV-1 RNA levels patient age, CD4+ count, and me- an increase in CD4+ cells in peripheral and lower median CD4+ count, and dian follow up were 35.9 years, 199 blood and lymph nodes, but not in the all had 1 or more NNRTI mutations. cells/μL, and 89.7 weeks, respectively. lamina propria. In patients who began Viral genotypes showed that 6 of the The patients were randomized in a 3 antiretroviral therapy in the acute and 9 individuals who did not respond to × 2 × 2 factorial design to: A) zid- early stages of infection, the mean in- therapy in the once-daily arm also had ovudine/lamivudine, zidovudine/di- crease in peripheral blood CD4+ counts K65R mutations. danosine, or stavudine/lamivudine; B) was 388 cells/μL and the parafollicular Walker and colleagues (Abstract efavirenz or nevirapine; and C) com- T-cell zone was 12.5% occupied. In pa- 506) presented 48-week results of the munity-based directly observed ther- tients who initiated therapy with estab- Evaluating the Safety of Nevirapine or apy or standard of care. There were lished infection in the presymptomatic (NORA) trial, a randomized also 2 balanced strata of CD4+ cell phase the increase in peripheral blood substudy of the Development of Anti- counts: below 201 cells/μL with any CD4+ count was 176 cells/μL and the retroviral Therapy in Africa (DART) trial viral load, and between 201 and 350 parafollicular T-cell zone was 13.65% in Uganda of 600 antiretroviral-naive cells/μL with plasma HIV-1 RNA above occupied. Earlier initiation of antiretrovi- ral therapy was associated with greater patients with CD4+ counts below 200 4.74 log10 copies/mL. The analysis was cells/µL. The trial compared zidovu- undertaken after the Data and Safety increases in the central memory cell pop- dine 300 mg/lamivudine 150 mg plus Monitoring Board (DSMB) suspended ulation of the Peyer’s patches. There was abacavir 300 mg twice daily with zi- the zidovudine/-containing no change in measured T-cell subsets in dovudine 300 mg/lamivudine 150 mg arm owing to inferiority in the pri- patients who initiated antiretroviral ther- plus nevirapine 200 mg twice daily and mary endpoint of virologic failure. The apy after being diagnosed with AIDS. was placebo-controlled for the first 24 authors pooled data from the 2 NNRTI Thus far, studies of the immuno- weeks. Baseline median CD4+ count arms and compared patients receiv- logic and virologic outcomes of early was 99 cells/µL and mean plasma HIV- ing zidovudine/didanosine with those treatment of primary HIV disease have been contradictory.1-3 Four abstracts at 1 RNA was 5.4 log10 copies/mL. At 48 receiving zidovudine/lamivudine or weeks, 77% of the nevirapine arm and stavudine/lamivudine. The rate of viro- this year’s conference used data from 62% of the abacavir arm had plasma logic failure with genotypic resistance large cohort studies to examine this, but did not end controversy. Similar HIV-1 RNA levels below 1.7 log10 cop- was 11% in the zidovudine/didanosine ies/mL (P < .001). The CD4+ cell arm and 2% in the zidovudine/lamivu- definitions of primary infection were count increase at 48 weeks was sta- dine or stavudine/lamivudine arm (P used in each of the following studies. tistically significantly higher in the ne- = .0002). No difference in death rate Steingrover and colleagues (Abstract virapine arm (173 cells/µL) than in the or time to first treatment-limiting tox- 124LB) used data from 2 large cohorts abacavir arm (147 cells/µL; P = .006). icity was observed in either nRTI arm. of HIV-seropositive patients in Dutch Despite the greater HIV-1 RNA level Unexpectedly, there were no differ- treatment centers, the Amsterdam Co- decreases and CD4+ cell increases, ences between the community-based hort Study and the Athena cohort, to the authors noted a trend suggesting directly observed therapy and stan- examine the immunologic and virologic clinical outcome superiority of the aba- dard-of-care arms, which the authors outcomes of initiating potent antiretro- cavir arm at 48 weeks, with 29 (10%) suggested was due to overall low rates viral therapy within 6 months of HIV of individuals in the nevirapine arm of virologic failure. No results were seroconversion. Of the 332 patients developing new World Health Organi- given comparing efavirenz and nevi- identified with primary HIV-1 infection, zation (WHO) stage IV events or death, rapine groups. 64 were treated with potent antiretrovi-

53 Conference Highlights - Advances in Antiretroviral Therapy Volume 15 Issue 2 April/May 2007

Table 2. Selected Trials of Antiretroviral Therapy in Treatment-naive Patients

Study Name Population Regimen(s) Baseline Follow-up Response Comments Abstract No. CD4+ Time cells/µL, Description Log10 copies of HIV RNA/mL

TMC278-C204 33% female Randomized to: 203 48 weeks Primary endpoint Some differences in Abstract 144LB 53%-56% rilpivirine 25 mg qd (median) of intent-to-treat side-effect profiles: analysis: Efficacy and nonwhite rilpivirine 75 mg qd 4.9 Incidence of rash safety testing of 3 rilpivirine 150 mg qd (median) Rilpivirine arms: and central nervous doses of rilpivirine or 77%-81% with system side effects <50 copies/mL were significantly (TMC278), an efavirenz 600 mg qd investigational Efavirenz arm: lower in the NNRTI with plus: 81% with <50 rilpivirine arms. activity against zidovudine/ copies/mL P = ns Rilpivirine associated HIV-1 resistant to lamivudine (76%) CD4+ count rise: with lower total currently available cholesterol, lower NNRTIs or Rilpivirine arms: LDL, and lower tenofovir/ 123-145 cells/μL triglycerides, emtricitabine (24%) Efavirenz arm: although the 125 cells/μL P = ns efavirenz group had (n=368) a higher HDL. Complete resistance analysis was not available.

ACTG A5073 Plasma HIV-1 Lopinavir 400 mg/ 197 48 weeks Difference in plasma Probability of RNA >3.3 log ritonavir 100 mg soft (median) HIV-1 RNA at 48 sustained virologic Abstract 138 10 copies/mL gel capsule 400/100 mg, weeks between qd response at 48 weeks Comparison of qd 4.8 Stratified by self-administered bid (median) and bid groups was in higher stratum (with or without 0.03 log copies/mL was higher in bid plasma HIV-1 Lopinavir 800 mg/ 10 DOT) versus bid (95%CI, –0.07-0.12) group (0.89; 95% CI, lopinavir/ritonavir RNA < or ≥5.0 ritonavir 200 mg, log copies/mL self-administered qd No significant 0.79-0.94) than in the 10 qd self-administered Non-blinded Lopinavir 800 mg/ difference in probability of group (0.76; 95% CI, ritonavir 200 mg via 0.64-0.84). DOT qd sustained virologic response between plus: DOT and qd, self- emtricitabine/ administered arms at stavudine 24 and 48 weeks or emtricitabine/ tenofovir (n=402)

DAUFIN Study CD4+ count Lamivudine 300 mg/ 207 12 weeks 7 early non- The trial steering Abstract 503 <350 cells/µL tenofovir 245 mg/ (median) responses committee stopped nevirapine 400 mg qd the study. Non-inferiority trial Non-blinded 4.85 19% early non- of qd nevirapine vs (n=71) (n=36) (median) response rate The definition of early bid nevirapine non-response was plasma HIV-1 RNA Preliminary results with either <2.0 log10 copies/mL decrease Zidovudine 300 mg/ 209 12 weeks 0 early non- or rebound of >1.0 lamivudine 150 mg/ (median) responses log10copies/mL nevirapine 200 mg 4.94 bid 1 or more NNRTI (median) resistance mutations (n=35) seen in all cases. 54 (Continued on next page) International AIDS Society–USA Topics in HIV Medicine

Table 2. Selected Trials of Antiretroviral Therapy in Treatment-naive Patients (cont’d)

Study Name Population Regimen(s) Baseline Follow-up Response Comments Abstract No. CD4+ Time cells/µL, Description Log10 copies of HIV RNA/mL

NORA Trial, Ugandan adults Zidovudine 300 mg/ 99 48 weeks HIV-1 RNA <50 More subjects in the nested substudy 72% women lamivudine 150 mg, (median) copies/mL at week nevirapine arm died within DART abacavir 300 mg bid 48: 62% or developed WHO median age, 5.4 (mean) Abstract 506 Mean CD4+ count grade IV events: 36 17 (6%) vs 29 (10%) Comparison of increase from 19% WHO baseline: 147 cells/µL P = .06 abacavir-based vs stage IV nevirapine-based regimens CD4+ count Zidovudine 300 mg/ HIV-1 RNA <50 <200 cells/µL lamivudine 150mg, copies/mL at week (n=600) nevirapine 200 mg 48: 77% bid (P < .001) Mean CD4+ count increase from baseline: 173 cells/µL (P = .006)

Tshepo Study Botswanan Zidovudine/ 199 89.7 Rates of virologic Increase in CD4+ cells, Abstract 507 adults didanosine + NNRTI (median) weeks failure with percentage of patients (median) genotypic resistance: with undetectable Comparison 69.4% 5.3 female (median) 11% plasma HIV-1 RNA, of didanosine- death rates, and time containing regimen median age, to first treatment- to other nRTIs 35.9 modifying toxicity Trial also looking at Stratified to were equivalent in the Zidovudine/lamivudine 2% 2 NNRTIs and DOT CD4+ count 2 arms. vs standard of care <201 or 201- or (P = .0002) Zidovudine/ 350 cells/µL stavudine/lamivudine didanosine- with plasma + NNRTI containing arms were HIV-1 RNA suspended by the

> 4.74 log10 DSMB. copies/mL (n=650)

NNRTI indicates nonnucleoside analogue reverse transcriptase inhibitor; LDL, low-density lipoprotein cholesterol; HDL, high-density lipoprotein cholesterol; ACTG, AIDS Clinical Trials Group; CI, confidence interval; DOT, directly observed therapy; WHO, World Health Organization; nRTI nucleoside analogue reverse transcriptase inhibitor; DSMB, Data Safety Monitoring Board; qd, once-daily; bid, twice-daily. ral therapy within 180 days of serocon- between the 2 groups. There was no HIV-1 infection, 95.5% were men and version, and 32 subsequently stopped difference in the CD4+ count decline 144 started antiretroviral therapy either the therapy. Higher plasma HIV-1 RNA between the untreated patients and pa- before or during seroconversion. The levels at seroconversion independently tients after treatment interruption. median CD4+ cell count was lower and predicted initiation of early antiretrovi- Koegl and colleagues (Abstract 125LB) the median plasma HIV-1 RNA level was ral therapy. Viral load at 7 weeks post- performed a similar analysis using data higher in the treatment group than in the treatment interruption was lower in from 2 German cohorts of patients with non-treatment group: 453 versus 629 the treatment interruption group than primary HIV-1 infection who were or cells/µL (P = .001), and above 5.7 versus at 7 weeks post-seroconversion among were not treated with early antiretrovi- 5.38 log10 copies/mL (P < .001), respec- patients who did not initiate treatment ral therapy (the Prime-DAG cohort and tively. One hundred of the 144 patients

(−0.6 log10 copies/mL; P < .001). This the Ac-DAG cohort, respectively) and who initiated treatment stopped antiret- difference decreased over time, and at found differences in both viral load and roviral therapy after a median time of approximately 100 weeks the plasma CD4+ count in treated versus untreat- 9.5 months (range, 2.1-28.7 months). HIV-1 RNA levels were indistinguishable ed groups. Of the 200 cases of primary Although the plasma HIV-1 RNA levels

55 Conference Highlights - Advances in Antiretroviral Therapy Volume 15 Issue 2 April/May 2007

differed significantly between treated Europe (CASCADE) cohort. After adjust- for the patients from the OK and OK04 and untreated patients at 6 months (4.4 ing for confounders, rate of CD4+ cell trials were 662 cells/μL and 474 cells/µL, log10 copies/mL vs 5.0 log10 copies/mL; P decline over the 3 years following sero- respectively, and baseline plasma HIV-1 = .01), they did not differ significantly conversion was greater in the untreated RNA levels before receiving antiretrovirals at 12 months (4.58 vs 4.72 log10 copies/ controls than in the treated case patients, were 5.1 log10 copies/mL in both trials. mL; P = ns). The absolute CD4+ counts with a mean decrease of 51 cells/µL per Of 121 patients, 15 had loss of virologic were not significantly different at 6 or 12 year in the case patients (95% CI; 32-69) suppression by week 48, with a Kaplan- months. However, 12 months after treat- and 77 cells/µL per year in the controls Meier probability of loss of virologic sup- ment cessation, the CD4+ count had (95% CI; 65-89). The estimated hazard pression of 12.7%. Independent factors increased by 60 cells/µL in the treated ratio (HR) for the combined events of associated with loss of virologic suppres- group, and 12 months after seroconver- antiretroviral treatment initiation and sion were low adherence (HR, 6.3; 95% sion, the CD4+ count had decreased by a CD4+ count below 350 cells/µL was CI, 2.0-19.6; P = .002), lower baseline 86 cells/µL in the untreated group, a sta- 1.445 (95% CI, 1.020-2.054, P = .039) hemoglobin (HR per g/dL, 0.68; 95% CI, tistically significant difference (P = .01). for the untreated controls compared with 0.50-0.92; P = .013) and nadir CD4+ Seng and colleagues (Abstract 347) the treated cases. Plasma HIV-1 RNA lev- count below 100 cells/µL (HR, 4.1; 95% found no difference in CD4+ count els did not show a statistically significant CI, 1.3-13.5; P = .02). trends in patients in the Agence Natio- difference between the 2 groups either Arribas and colleagues (Abstract nale de Recherches Sur le Sida (ANRS) at 18 months or 2 years after serocon- 638) reported drug resistance out- PRIMO cohort with primary HIV-1 in- version. It is unclear what effect, if any, comes from the OK04 trial. During the fection after interruption of potent the significantly longer follow-up time trial, genotype testing was performed antiretroviral therapy compared with for the case patient group (2.45 years) on all plasma samples in which HIV-1 patients in the ANRS SEROCO cohort compared with the controls (1.20 years, RNA was greater than 2.7 log10 copies/ with primary HIV-1 infection who never P < .001) had on this analysis. mL. Eleven subjects in the monother- received antiretroviral therapy. The 170 The above studies indicate that early apy arm and 4 subjects in the control patients included from the ANRS PRIMO antiretroviral treatment in primary HIV- arm qualified for genotype by these cohort began antiretroviral therapy with- 1 infection may have beneficial virologic criteria (P = .07), and 2 isolates in the in 3 months of their HIV-1 diagnosis. All and immunologic effects, though the re- monotherapy arm and 1 in the control responded with plasma HIV-1 RNA lev- sults are inconsistent and limited by the arm had major PI mutations as defined els below 2.7 log10 copies/mL within 6 studies’ observational natures. The ques- by the International AIDS Society-USA months, continued treatment for at least tion of whether early antiretroviral treat- 2006 guidelines (V82A or M46I).4 The 6 months (average duration, 19 months), ment in primary HIV-1 infection should authors concluded that the incidence of and discontinued treatment for at least 3 become standard-of-care awaits results PI resistance over the first 48 weeks of months (average duration, 21 months). from randomized, controlled trials that the OK04 study was low, and similar be- Mean CD4+ count at 36 months after are currently underway. tween the 2 treatment arms. They also treatment interruption in the PRIMO co- noted that 5 of 11 patients with plasma hort (n=170) and after HIV-1 infection HIV-1 RNA levels above 2.7 log copies/ Antiretroviral Treatment 10 in the SEROCO cohort (n=123) were Strategies mL did not have resistance mutations, equal at 416 cells/µL (95% CI for PRIMO, remained on monotherapy, and had re- 369-464; for SEROCO, 360-476). Tran- Lopinavir/Ritonavir Monotherapy as suppressed their plasma HIV-1 RNA to sient antiretroviral therapy initiated dur- a De-escalation Strategy less than 1.7 log10 copies/mL. ing primary HIV-1 infection did not ex- Campo and colleagues (Abstract tend time spent off treatment or time to In the OK and OK04 studies (Abstracts 514) reported results from the M03-613 a CD4+ count of below 350 cells/µL. 513 and 638) patients on a regimen trial, which randomized 155 antiretro- In a case-controlled study of patients of lopinavir/ritonavir plus 2 nRTIs with viral-naive patients with HIV-1 infec- with primary HIV-1 infection who re- plasma HIV-1 RNA levels below 1.7 log10 tion in a 2:1 ratio to: lopinavir/ritonavir ceived potent antiretroviral therapy copies/mL for at least 6 months and no plus zidovudine/lamivudine induction (Abstract 348), early antiretroviral treat- history of virologic failure on PIs were therapy for at least 24 weeks, followed ment correlated with immunologic but randomized to either continue treatment by maintenance with lopinavir/ritona- not virologic outcomes. Eighty-nine with lopinavir/ritonavir plus 2 nRTIs or vir monotherapy after 3 consecutive patients with primary HIV-1 infection to lopinavir/ritonavir monotherapy. Data months of plasma HIV-1 RNA levels who received 3 months of antiretroviral from 121 participants in both open-la- below 1.7 log10 copies/mL, or efavirenz therapy in the St. Mary’s cohort were bel trials assigned to lopinavir/ritonavir plus zidovudine/lamivudine. Eligible matched for age, sex, HIV-1 risk group, monotherapy were analyzed to identify subjects had plasma HIV-1 RNA levels year of estimated seroconversion, and risk factors for loss of virologic suppres- above 1000 copies/mL, were antiret- seroconversion window interval, with sion, defined as a plasma HIV-1 RNA level roviral naive, and had no evidence of

179 patients from the Concerted Action above 1.7 log10 copies/mL at 48 weeks resistance to study drugs. At 96 weeks, on Seroconversion to AIDS and Death in (Abstract 513). Baseline CD4+ counts 60% of the lopinavir/ritonavir mono-

56 International AIDS Society–USA Topics in HIV Medicine

therapy arm and 63% of the efavirenz in the treatment interruption group vs postpartum year. Although the data are plus zidovudine/lamivudine arm had 3.8 log10 copies/mL in the lamivudine reassuring that stopping antiretroviral plasma HIV-1 RNA levels below 1.7 group). Time to immunologic or clini- therapy after delivery does not lead to log10 copies/mL. In subjects who dein- cal failure (defined as CD4+ count be- a more rapid decline in CD4+ count, tensified to monotherapy, 32 had con- low 350 cells/μL or Centers for Disease studies with larger sample sizes and firmed plasma HIV-1 RNA levels above Control and Prevention [CDC] class B longer follow-up periods are needed.

1.7 log10 copies/mL. Time to loss of vi- or C diagnosis) took a median of 20 rologic response to a level above 1.7 weeks (interquartile range [IQR], 16- Interleukin-7-based Therapies log10 HIV-1 RNA copies/mL was statis- 84 weeks) for the treatment interrup- tically significantly different between tion group and 84 weeks (IQR, 36-144 Interleukin-7 (IL-7) is a cytokine that the lopinavir/ritonavir (approximately weeks) for the lamivudine monothera- induces T-cell development, homeo- 60% maintaining response at 64 py group. In analysis of variance (ANO- stasis, thymopoiesis, and T-cell mat- weeks) and efavirenz arms (approxi- VA), the treatment interruption group uration. It has been shown to cause mately 90% maintaining response at had greater declines in CD4+ count dose-dependent increases in T cells 64 weeks; P < .0001). When the vi- over time than the lamivudine mono- in patients undergoing chemotherapy rologic threshold for time to loss of vi- therapy group (P = .0095), as did pa- for cancer. rologic response was raised to greater tients with baseline CD4+ counts of In an evaluation the safety and bio- than 2.7 log10 HIV-1 RNA copies/mL, 700 cells/μL or lower compared with logic effects of recombinant human IL- there was no statistically significant patients with baseline CD4+ counts of 7 in patients chronically infected with difference between the groups. Low greater than 700 cells/μL (P < .0001). HIV-1 (Abstract 127), 6 patients with adherence, defined as a subject report- The plasma HIV-1 RNA trend did not CD4+ counts between 100 and 400 ing at least 1 missed lopinavir/ritona- differ statistically significantly over cells/μL and plasma HIV-1 RNA levels vir dose (P = .07), and baseline CD4+ time between the 2 groups. By 144 below 1.7 log10 copies/mL received 8 cell count (P = .06) predicted virologic weeks, 93% of patients in the treat- subcutaneous injections of 3μg/kg IL-7 rebound in the monotherapy group. ment interruption group and 90% of over 18 days. Plasma HIV-1 RNA levels

patients in the lamivudine monother- remained below 1.7 log10 copies/mL Treatment Interruptions apy group had discontinued the study. for all patients and no biologic adverse There were more grade III and IV ad- effects above grade II were observed. In contrast to last year’s conference, verse events in the treatment inter- The median CD4+ count increased few new antiretroviral therapy outcome ruption group than in the lamivudine from 210 cells/μL at baseline to 405 data were presented on treatment in- monotherapy group (8 vs 1; P = .012). cells/μL at day 21 and remained above terruption strategies. Some further Lamivudine monotherapy in this study baseline at 300 cells/μL at week 12 analysis of complications arising from of treatment-experienced patients led (P < .01). An expansion of CD8+ cells interruption is reviewed elsewhere in to persistently better clinical and viro- expressing CD28 was also noted, sug- this issue (see “Complications of HIV logic outcomes than complete treat- gesting that IL-7 may promote CD8+ Disease and Antiretroviral Therapy”), ment interruption. cell maturation in vivo. The trial con- and selected trials on outcomes are Watts and colleagues (Abstract 751) tinues to examine the efficacy and below. examined the effects of treatment inter- safety of higher doses of IL-7. The Experienced (E)-184V study ruption after pregnancy in the Women Sereti and colleagues (Abstract 128) (Abstract 516) is a prospective, open- and Infant Transmission Study (WITS) report the results of ACTG A5214, a label study. Patients in whom lamivu- cohort. The 206 women included in randomized, placebo-controlled, dou- dine-containing antiretroviral regimens the analysis were antiretroviral-naive, ble-blind phase I dose escalation study were failing and who had document- had CD4+ counts above 350 cells/μL, of IL-7. Sixteen participants (12 active, ed M184V mutations, CD4+ counts and were similar in baseline character- 4 placebo) with a median CD4+ count above 500 cells/μL, and plasma HIV-1 istics to the larger WITS cohort. One of 601 cells/μL and plasma HIV-1 RNA

RNA levels above 1000 copies/mL, and hundred and forty-seven women con- level of below 1.7 log10 copies/mL were who requested treatment interrup- tinued antiretrovirals post-partum, and stratified by plasma HIV-1 RNA into 1 tion, were randomized to either treat- 59 stopped therapy. Those continu- of 2 groups, below 1.7 log10 copies/mL ment interruption or lamivudine 300 ing therapy were slightly older (mean or 1.7 to 4.7 log10 copies/mL. They mg daily as monotherapy. Data were ages 27.7 years vs 25.9 years; P = were then randomized in a 3-to-1 fash- presented for 144 weeks and the 29 .04) and a smaller percentage of them ion to receive one dose of 3, 10, 30, patients in each group did not differ in had CD4+ counts above 500 cells/μL or 60 μg/kg of IL-7 or placebo subcu- baseline parameters, including CD4+ (54.4% vs 71.2%; P = .03). Neither taneously. Two dose-limiting toxicities count (566 cells/μL in the treatment the slopes of the CD4+ cell count were seen at the 60 μg/kg dose, there- interruption group vs 580 cells/μL in changes, plasma HIV-1 RNA levels, nor fore the maximum tolerated dose was the lamivudine monotherapy group) the number of class B events differed set at 30 μg/kg. For the placebo group, or HIV-1 RNA level (3.7 log10 copies/mL between the 2 groups during the first no statistically significant increase in 57 Conference Highlights - Advances in Antiretroviral Therapy Volume 15 Issue 2 April/May 2007

within-subject change in CD4+ count a combination of 2 nRTIs and a NNRTI cases per 1000 person-years). Crude from baseline was seen at day 1, 4, 14, as the most frequent first-line regi- mortality at 4 years was approximate- or 28. For the IL-7 group, a statistically men. However, the number of possible ly 15% in sub-Saharan Africa, com- significant within-subject CD4+ count first-line regimens used to treat 90% pared with approximately 5% in North change from baseline occured at day of antiretroviral-naive patients is 59 in America and Europe. A rapid increase 1 (decrease of 426 cells/μL; P = 423) North America, 47 in Western Europe, in cumulative mortality in the first few and day 14 (increase of 186 cells/μL; and 3 in all regions of Africa and Asia. months of treatment in sub-Saharan P = .04). At day 28, the within-subject In an analysis of loss to follow up, Africa was not observed in the ART-CC CD4+ count in the IL-7 group had in- Egger presented data from the Anti- cohort. Breaking down mortality rates creased by 213 cells/μL, but this was retroviral Therapy in Lower Income within the first year of treatment by not statistically significant. Countries (ART-LINC) collaboration on cohort, and adjusting for baseline age, 16 treatment programs in resource- sex, CD4+ cell count, year, and dis- Antiretroviral Therapy in limited settings, 12 of which use active ease stage, a wide range of mortality Resource-limited Settings tracing of patients. He included 5575 was observed in the North American adult patients (46% women) initiating and European cohorts, some with rates One of the most exciting aspects of this antiretroviral therapy with a median of 4% to 6%, similar to those observed year’s conference was the increasingly age of 35 years, and found that 4% of in sub-Saharan Africa. Egger conclud- global nature of the event. Several ple- patients did not return after their first ed that many patients in resource-lim- nary sessions and many abstracts pre- visit and 17% were lost to follow up af- ited settings are starting antiretroviral sented data from resource-limited set- ter the first 6 months. The HR for loss therapy later than recommended, but tings, and the level of commitment to to follow up increased in each calendar that virologic and immunologic re- HIV/AIDS treatment in resource-limit- year since 2000. In 2001 and 2002 the sponses are similar across regions. He ed settings was inspiring. Results from HR was 2.77 (95% CI, 1.69-4.55) and highlighted the problem of loss to fol- selected studies in resource-limited in 2003 and 2004 it was 7.86 (95% CI, low up in programs, which likely leads settings are summarized in Table 3. 4.71-13.1). Patients with CD4+ counts to underestimates of mortality, and the below 50 cells/μL were also more like- need for continued monitoring in the Adult Treatment Outcomes ly to be lost to follow up, highlighting setting of rapid scale-up in resource- in Large Cohorts the need for active follow up in the limited settings. Finally, he noted that determination of mortality estimates. although mortality rates are higher, Matthias Egger delivered a plenary Curves for virologic response, defined particularly in the first few months talk (Abstract 62) entitled “Outcomes as plasma HIV-1 RNA below 2.7 log10 of treatment, it is possible to achieve of Antiretroviral Therapy in Resource- copies/mL, were developed using data mortality rates in resource-limited set- limited Settings.” He pooled data from from the Swiss HIV Cohort and the Gu- tings that are comparable with some several sources, including the Antiret- gulethu and Khayelitsha township co- cohorts in North America and Europe. roviral Therapy Cohort Collaboration horts in South Africa; responses were El-Sadr and colleagues (Abstract 534) (ART-CC), a network of European and similar between the cohorts, as were presented data on 171,259 patients re- North American cohorts, and the Inter- the rates of virologic rebound. In con- ceiving care from International Center national Epidemiological Databases to trast, rates of treatment change varied for AIDS Care and Treatment Programs Evaluate AIDS (IeDEA), a collaborative dramatically between the cohorts: at (ICAP)-sponsored sites in 7 different effort to establish regional networks 24 months approximately 60% of the African countries, 71,482 of whom ini- of treatment sites throughout Africa, Swiss cohort had changed regimens, tiated potent antiretroviral therapy be- Latin America, and Asia. Using data compared with approximately 35% of tween July 2004 and December 2006. from 33,008 treatment-naive patients the South African cohorts. The major- The investigators noted wide variations across 42 countries and 176 treatment ity of this difference was attributed to in populations, treatment outcomes, sites, Egger and colleagues determined changes for toxicity and by patient re- loss to follow up, and mortality among that the median CD4+ count in se- quest, not for treatment failure. patients enrolled at each treatment site. lected countries at initiation of ther- An analysis of the 4 sub-Saharan Of the 116,609 patients who received apy ranged from 164 to 187 cells/μL Africa cohorts in the IeDEA collabo- HIV care from October 2006 to Decem- in North America, 87 to 125 cells/μL ration and the ART-CC data revealed ber 2006, 15% were eligible for antiret- in sub-Saharan Africa, and 53 to 206 that tuberculosis (TB) is currently the roviral treatment. Initiation of therapy cells/μL in Asia. Although the trend in most common opportunistic infection varied from site to site, with 47% of median CD4+ count increased from in both resource-limited and industri- eligible patients initiating antiretroviral 2001 to 2005 in sub-Saharan Africa, alized settings, although the incidence therapy within 3 months in South Af- it remains significantly lower than in of TB is much higher in sub-Saharan rica compared with 100% of eligible European and North American co- Africa (approximately 250 cases per patients in Rwanda. Baseline CD4+ horts. The investigators found that all 1000 person-years) than in Europe counts were low and ranged from 104 areas except for Western Europe used and North America (approximately 25 to 198 cells/μL. Most adult patients ini-

58 International AIDS Society–USA Topics in HIV Medicine

tiated treatment with stavudine/lamivu- years and median follow-up time was from one of the longest-running treat- dine/nevirapine, except in South Africa, 2.2 years. All patients initiated first-line ment cohorts in a resource-limited set- where stavudine/lamivudine/efavirenz antiretroviral treatment; 64.6% received ting, the Khayelitsha township program was the most common regimen. After efavirenz-based regimens (60% female) in Cape Town, South Africa. A total of 12 months on therapy, the average me- and 35.4% received nevirapine-based 2565 antiretroviral-naive patients initiat- dian CD4+ count was 291 cells/μL, and regimens (68% female). The baseline ed therapy between 2001 and mid-2006, in the overall cohort 98% of adults and mean CD4+ count was 146 cells/μL for 70% of whom were female. Median 93% of children remained on first-line the efavirenz group and 167 cells/μL for CD4+ count at treatment initiation in- regimens. The proportion of patients the nevirapine group, and plasma HIV-1 creased over time from 44 cells/μL in known to have died without active case- RNA level was above 5.0 log10 copies/mL 2001 to 2002, to 99 cells/μL in 2005. finding ranged from 5% to 6% when for 61% and 55% of the efavirenz and After 3 years of antiretroviral therapy, averaged by country, but some sites in nevirapine groups, respectively. CD4+ median CD4+ count was 422 cells/μL Ethiopia and Mozambique reported that count outcomes data were not present- and plasma HIV-1 RNA was below 2.6 more than 15% of patients on anitret- ed, but in a multivariate analysis control- log10 copies/mL in 80% of the patients. rovirals were known to have died. The ling for adherence and other baseline Mortality at 6 months after antiretrovi- proportion of patients lost to follow up variables, the HR for time to virologic ral initiation decreased each year, and without active case-finding ranged from failure after initial suppression was 0.72 was 12.4% in 2001 and 5.4% in 2005. 1% in Rwanda to 17% in Kenya. (95% CI, 0.59-0.88) for efavirenz com- Determinants of mortality included The importance of active case-find- pared with nevirapine. Low adherence an initial CD4+ count of less than 50 ing of patients who are lost to follow up based on pharmacy claims data, low cells/μL, WHO stage IV disease, and a was highlighted in a retrospective cohort baseline CD4+ count, and high base- history of or current Kaposi’s sarcoma study among 410 HIV-1-infected adults line plasma HIV-1 RNA correlated with (KS). At 48 months on treatment 14% consecutively presenting to an urban decreased time to virologic failure. had started second-line therapy, and clinic in Botswana (Abstract 537). Stan- Determinants of mortality were evalu- the proportion of patients remaining in dard of care in the clinic was active case- ated in a cohort of 1120 antiretroviral-na- care at 54 months (combining mortal- finding for all patients lost to follow up ive patients enrolled in a home-based ity and loss to follow up) was 78%. and involved telephone calls and home treatment program in Uganda (Ab- Two abstracts presented data on re- visits if needed. Patient outcomes were stract 34). Median age was 38 years, sponses to second-line therapy in re- retrospectively classified by passive case- 73% were female, and 39% were source-limited settings from Médecins finding, in which patients were classified WHO stage III or IV when they initiated Sans Frontières-supported programs. The as dead if their death was recorded in therapy. Median baseline CD4+ count first, presented by Calmy and colleagues the clinic chart, and lost to follow up if and HIV-1 RNA level were 127 cells/μL (Abstract 35), detailed outcomes from their last clinic contact was more than and 5.3 log10 copies/mL, respectively. 22 countries in Africa, Asia, and Central 30 days past their last visit. Median du- Early mortality, defined as death oc- America. Of more than 80,000 antiret- ration of follow up was 44 weeks among curring within 3 months of treatment roviral-naive patients first initiating an- the 410 patients initiating antiretroviral initiation, was 16.4 per 100 person- tiretroviral therapy since 2001 at a Mé- therapy during the study period. Passive years of observation in the cohort. decins Sans Frontières site, 354 (0.4%) case-finding classified 29 patients (7%) Mortality decreased in each time peri- had changed regimens. The median as dead and 68 of 410 patients (17%) as od to a low of 1.3 per 100 person-years age of those switching was 35 years, lost to follow up. Active case-finding clas- of observation at 18 to 24 months on 57% were female, and 87% were WHO sified 69 patients as dead (17%) and 22 treatment. Baseline factors associated stage III or IV at therapy initiation. Stavu- (5%) as lost to follow up. The 52-week with mortality were low CD4+ count, dine/lamivudine/nevirapine was the ini- Kaplan-Meier survival estimates differed hemoglobin less than 10 g/dL, body tial regimen for 91% of the patients. Of significantly: 0.93 (95% CI, 0.88-0.94) mass index (BMI) less than 18 kg/m,2 the second-line regimens, 47% were for passive and 0.79 (95% CI, 0.74-0.81) and a history of prior TB. Adherence to -based and 46% were lopina- for active case-finding. Baseline CD4+ antiretroviral treatment strongly cor- vir/ritonavir-based. The median CD4+ count below 100 cells/μL and male sex related with mortality in reported ad- count at switch was 99 cells/μL and the were independently associated with herence of less than 90% in the first 6 median plasma HIV-1 RNA level was death in the first 12 months of antiret- months (HR, 3.3; P < .001) and after 4.64 log10 copies/mL for those programs roviral therapy. the first 6 months (HR, 7.4; P < .001). with virologic testing. The median in- Nachega and colleagues (Abstract The most common conditions associ- crease in CD4+ count was 91 cells/μL at 33) examined the effectiveness of efavi- ated with death in first 3 months on 6 months and 113 cells/μL at 12 months. renz- and nevirapine-based antiretroviral treatment were no diagnosis, TB, cryp- Approximately 6% were lost to follow up regimens in a cohort of 2821 patients on tococcal disease, and oropharyngeal at 5 months, and 7% of the patients had antiretroviral therapy in 9 Southern Af- candidiasis. died by 6 months. Probabilities of surviv- rican countries between January 1999 Van Custem and colleagues (Ab- al within the cohort, including death and and March 2003. Mean age was 37 stract 535) presented 5 years of data loss to follow up, were 0.91 at 6 months

59 Conference Highlights - Advances in Antiretroviral Therapy Volume 15 Issue 2 April/May 2007

(IQR, 0.88-0.95 months) and 0.86 at 12 sites in Botswana, Uganda, Lesotho, months, and more than 60 months, re- months (IQR, 0.82-0.91 months). Swaziland, and Malawi. Mean age at spectively. Severe immunodeficiency Ferradini and colleagues (Abstract antiretroviral initiation ranged among and severe anemia were associated 36LB) examined the efficacy of lopina- sites from 5.1 to 7.8 years, 50% were with increased risk of death. vir/ritonavir-based second-line therapy female, and 50% to 92% had WHO Outcomes of 370 children receiv- at several Médecins Sans Frontières stage III or IV disease. The vast majority ing potent antiretrovirals with NNRTIs sites in Cambodia. One hundred and of children were on first-line antiretrovi- (48.6%) and PIs (51.4%) were com- thirteen patients who had been followed ral regimens, with 50% having received pared in a clinic in Cape Town, South up for at least 6 months on second-line zidovudine/lamivudine/nevirapine. In Africa (Abstract 728). The NNRTI group therapy were identified; 50% were fe- the Botswana clinic, the median CD4+ was 41% female compared with 53% male and median age was 38 years. cell percentage at baseline was 15, female in the PI group (P = .02), and The decision to stop first-line therapy compared with 8 in Uganda. In Botswa- the median age was 34.3 months and was based on immunologic and viro- na (n=880), the CD4+ cell percentage 21.8 months in the NNRTI- and PI- logic criteria in 35 and 78 patients, re- was 27 at 6 months, 30 at 12 months, based groups, respectively (P < .01). spectively. Median CD4+ count at regi- and 32 at 36 months. In Uganda, the Duration on therapy was longer for the men switch was 70 cells/μL and median CD4+ cell percentage was 18 at 6 NNRTI group (3 years) than for the PI plasma HIV-1 RNA level was 4.7 log10 months, 23 at 12 months, and 26 at 24 group (1.2 years; P < .001). Baseline copies/mL. The most frequent second- months. Plasma HIV-1 RNA data were CD4+ cell percentage was 13 and line regimens were didanosine/lami- available in the Botswana clinic, with plasma HIV-1 RNA was 5.5 log10 cop- vudine/lopinavir/ritonavir (n=47) and levels of below 400 copies/mL in 79%, ies/mL for both groups. At 24 months didanosine/zidovudine/lopinavir/ritona- 81%, and 71% of patients at 6, 12, there was no difference between groups vir (n=21), and the median duration of and 24 months, respectively. The crude in median CD4+ percentage (26.3) second-line therapy at the time of the mortality of the entire Botswana clinic and survival curves were superimpos- evaluation was 10.2 months. Median population, both on and off antiretro- able. However, plasma HIV-1 RNA lev- CD4+ count increase was 105 cells/μL viral therapy, decreased dramatically els differed, with 43% of the NNRTI at 6 months and 180 cells/μL at 12 from 4.7% in 2004 to 0.3% in 2006. group achieving virologic suppression months. Plasma HIV-1 RNA at evalua- At 2.5 years of follow up the Botswana at 24 months compared with 60% of tion was below 2.6 log10 copies/mL for clinic had 10% of its patient population the PI group (P = .05), and median 101 patients (89.4%), between 2.7 and on second-line regimens and 93% still plasma HIV-1 RNA was higher in the

3 log10 copies/mL for 6 patients (5.3%), alive and on antiretroviral therapy. NNRTI group than in the PI group between 3 and 4 log10 copies/mL for Arrivé and colleagues (Abstract 727) (3.8 log10 copies/mL vs 2.6 log10 cop- 2 patients (2.7%), and more than 4 presented data from 8 clinical centers ies/mL, respectively, P = .05). The log10 copies/mL for 4 patients (3.5%). participating in the KIDS-ART-LINC col- authors speculated that the effective- Genotypic analysis in all patients with laboration. Of 2142 children initiating ness of NNRTI-based regimens could plasma HIV-1 RNA above 2.7 log10 cop- antiretroviral therapy between 1 and 15 be impaired by drug-drug interactions, ies/mL did not reveal any protease years of age, 53.5% were 5 to 15 years suboptimal dosing, or pre-existing re- mutations, but 100% had NNRTI resis- old, 16.5% were 36 to 59 months old, sistance as a result of prior exposure tance and 91.5% had an M184V muta- 20.9% were 12 to 35 months old, and through prevention of mother-to-child tion. Other than low CD4+ cell count 9.1% were less than 1 year old. Based transmission (PMTCT) programs. at switch, there were no predictors of on CD4+ cell percentage, 65.7% of Kamya and colleagues (Abstract 732) second-line therapy failure. The authors the children met WHO criteria for se- examined predictors of long-term vi- concluded that short-term outcomes of vere immunodeficiency. PI-based regi- rologic failure in a prospective cohort empiric, second-line lopinavir/ritonavir- mens were used initially in 57.8% and of 250 children and 526 adults initiat- based regimens were successful and NNRTI-based regimens in 37.0%. Af- ing first-line antiretroviral treatment in that adherence, although not measured ter 1 year of antiretroviral treatment Uganda between April 2004 and June in this study, was a main determinant without active case-finding, 4.4% were 2005. The adult population was 69% of second-line regimen failure. dead and 12.2% were lost to follow up. female, had a mean age of 37 years, Estimated cumulative mortality was and 88% had WHO stage III and IV dis- Treatment Outcomes for Children in 5.5% (95% CI, 4.3-7.1) at 6 months ease. The children were 48% female, Large Cohorts and 6.5% (95% CI, 5.1-8.2) at 1 year. had a mean age of 9.2 years, and 98% The probability of death varied dra- had WHO stage III and IV disease. All Kline and colleagues (Abstract 79) matically by age group: 16.8% mor- initiated NNRTI-based regimens, with pooled database and medical record in- tality (95% CI, 11.7-23.7) among chil- stavudine/lamivudine/nevirapine be- formation for 11,926 children, including dren initiating antiretrovirals before 12 ing the most common in adults (73%) 5151 children receiving antiretroviral months of age compared with 4.0%, and zidovudine/lamivudine/efavirenz treatment through January 31, 2007, at 1.8%, and 4.3% mortality for those the most common in children (55%). 5 Baylor College of Medicine-supported initiating at 12 to 35 months, 36 to 59 Median CD4+ count was 99 cells/μL in

60 International AIDS Society–USA Topics in HIV Medicine Table 3. Selected Studies from Resource-limited Settings

Study Name Country, Treatment Baseline treatment regimen Baseline age, sex, clinical Baseline CD4+ cells/µL* CD4+ cells/µL * Response in Plasma Mortality Comments Program stage, treatment Response HIV RNA copies/mL* Abstract No. (No. Patients) Log10 Copies Duration of follow up experience HIV RNA/mL*

Efavirenz- vs 9 countries in southern Africa, nRTI + efavirenz 37.0 y, efavirenz: 60% female, Efavirenz 146 (mean) Data not In multivariate analysis Data not Low adherence, low baseline CD4+ Nevirapine-based ART Private-sector Aid for AIDS (64.6%) nevirapine: 68% female, Nevirapine 167 (mean) presented controlling for adherence, presented count, and high baseline plasma HIV Regimens: Adherence and Disease Management Program antiretroviral treatment-naive hazard ratio for time RNA levels correlate with decreased vs >5.0 efavirenz: 61% Virologic Outcomes Jan 1999-Mar 2003; to virologic failure after time to virologic failure nRTI + nevirapine >5.0 nevirapine: 55% initial suppression was Abstract 33 median, 2.2 y (35.4%) Results could be due to efavirenz 0.72 (0.59-0.88) for superiority or unmeasured (n=2821) efavirenz vs nevirapine confounders

Determinants of Mortality Uganda, Global AIDS Program Nevirapine/lamivudine/stavudine Median 38.0 y, 73% female, 127 (median) Data not Data not presented Defined early mortality as <_ Significantly more deaths from among HIV-infected Median, 2 y (96%) 39% WHO Stage III or IV, presented 3 mos, 16.4 per 100 person- wasting in 0-3 mos Individuals Receiving Home- Efavirenz/lamivudine/stavudine antiretroviral treatment-naive 5.3 (median) years Most common conditions based ART in Rural Uganda (4%) Mortality decreased in each contributing to death in first 3 mos Abstract 34 (n=1120) time period to 1.3 per 100 were: no diagnosis, Tb, cryptococcal person-years from 18-24 mos disease, o/p candida Baseline factors associated with mortality: CD4+ count 50-199 cells/ µL, Hgb <_ 10g/dL, BMI < 18 kg/m2, prior Tb, and depression index score

Variability in Populations Ethiopia, Kenya, Mozambique, Majority on stavudine/lamivudine/nevirapine, 58% female (of those on 104-198 At 6 mos: 246 No data available Mortality varied from 5% in The proportion of patients lost Enrolled and Their Outcomes Nigeria, Rwanda, South Africa, except South Africa: stavudine/lamivudine/ antiretrovirals), antiretroviral (range, 223-290) Rwanda, Mozambique, and to follow up, without active in HIV Care and Treatment Tanzania, ICAP-supported, efavirenz (86%) treatment-naive Tanzania to 15% in individual case-finding, ranged from 1% in HIV RNA n.a. At 12 mos: 291 Programs Across Countries in PEPFAR-funded (n=116,284 total; 71,482 on antiretrovirals) (range, 277-305) sites in Mozambique and Rwanda to 17% in Kenya Sub-Saharan Africa Sep 2004-Jun 2006 Ethiopia (without active case 98% of adult and 93% of children Abstract 534 finding) remained on first-line regimens

Clinical Outcomes and South Africa, government- Stavudine/lamivudine/efavirenz (37%) Median 32 y, 70% female, 44 (median, 2001-2002) At 3 years: At 3 years: Mortality at 6 mos (year of Determinants of mortality: initial Emerging Challenges after sponsored program Stavudine/lamivudine/nevirapine (43%) 90% WHO Stage III and IV, and 422 80% with <400 antiretroviral start): CD4+ count < 50 cells/µL, WHO 5 Years of ART in a South antiretroviral treatment-naive (median) stage IV disease, Kaposi’s sarcoma 2001-mid-2006 (n=2565) 99 (median, 2005) 12.4% (2001) African Township 5.4% (2005) at any point HIV RNA n.a. Abstract 535 Proportion remaining in care at 14% started second-line therapy by 54 mos: 78% 48 mos

Field Effectiveness of HAART Côte d’Ivoire, PEPFAR- Stavudine/lamivudine/nevirapine (50%) 34 y, 71% female, 77% WHO 116 (median) At 6 mos: +136 No data available 12-mo survival probability Lost to follow up at 12 mos: 19% in HIV-infected Adults in West sponsored Stavudine/lamivudine/efavirenz (22%) Stage III or IV, antiretroviral HIV RNA n.a. At 12 mos: +163 (baseline CD4+ count): Factors associated with mortality: Africa: The Aconda/ISPED/ treatment-naive At 18 mos: +213 < Mar 2004-Aug 2006 Zidovudine/lamivudine/efavirenz (21%) 77% (_ 50 cells/µL) baseline CD4+ count <50 cells/µL, EGPAF Program, Abidjan, Côte (in those still on 86% (51-100 cells/µL) male sex, older age, low baseline d’Ivoire 2004-06 (n=7862) treatment) 89% (101-150 cells/µL) Hgb, baseline BMI <18.5 kg/m2, Abstract 541 93% (>150 cells/µL) baseline WHO stage III or IV, care center

Catalyzing the Care and Botswana, Uganda, Lesotho, First-line therapy with zidovudine/lamivudine/ 5.1-7.8 y (mean), 50% female, Botswana: Botswana: Botswana: Botswana: crude mortality Botswana at 2.5 y: Treatment of HIV-infected Swaziland, and Malawi, nevirapine 50%-92% with WHO Stage III CD4+ percentage: 15 (n=880) at 6 mos: 79% <400 of entire clinic (on and off 10% switched to second or third- Children in Sub-Saharan joint Baylor, CDC, industry (n=5151) or IV, antiretroviral treatment- 0%<400 copies/mL at 6 mos: +27% at 12 mos: 81% <400 antiretrovirals): line treatment Africa: Early Outcomes from foundations, and government- naive at 12 mos: +30% at 36 mos: 71% <400 2003: 4.7% 93% alive and on treatment 5 Baylor College of Medicine sponsored at 36 mos: +32% 2004: 2.1% Centers Dec 2001-Jan 2007 Uganda: Uganda: 2005: 1.1% Abstract 79 CD4+ percentage: 8 at 6 mos: +18% 2006: 0.3% HIV RNA n.a. at 12 mos: +23% at 24 mos: +26%

Outcomes of Adults Receiving 22 countries in Africa, Asia, 91% had first-line stavudine/lamivudine/ Median, 35 y, 57% female, At first-line antiretroviral At 6 mos: + 91 No data available At 6 mos: ~7% died At 5.0 mos: 6% lost to follow up Second-line ART in Médecins and Central America, MSF- nevirapine at first-line antiretroviral initiation: (median) Probabilities of survival (death Factors associated with progression to Sans Frontières-supported supported programs 47% had second-line nelfinavir-based, 46% initiation: 87% WHO Stage III 63 (median), and at At 12 mos: +113 plus lost to follow-up): death: CD4+ nadir <50 cells/µL Projects in Resources-limited or IV, included only patients antiretroviral switch: Median time from antiretroviral had second-line lopinavir/ritonavir-based (median) At 6 mos: 0.91 Authors’ speculation: low rate of Countries initiation to switch 20 mos, 59% had didanosine-containing entering program who were 99 (median) antiretroviral treatment-naive At 12 mos: 0.86 second-line therapy use may be due to Abstract 35 median follow-up post-switch (n=352, 0.4% of adults initiating antiretroviral lack of availability, provider hesitation was 7 mos treatment with MSF since 2001) 4.64 (for those available) due to clinical status

BMI indicates body mass index; CDC, Centers for Disease Control and Prevention; HAART, highly active antiretroviral therapy; Hgb, FAR, United States President’s Emergency Plan for AIDS Relief; TB, Tuberculosis; WHO, World Health Organization. *CD4+ counts and HIV hemoglobin; ICAP, International Center for AIDS Care and Treatment Programs; MSF, Médecins Sans Frontières; n.a., not available; PEP- RNA are in units stated unless indicated otherwise. 61 Conference Highlights - Advances in Antiretroviral Therapy Volume 15 Issue 2 April/May 2007 Table 3. Selected Studies from Resource-limited Settings

Study Name Country, Treatment Baseline treatment regimen Baseline age, sex, clinical Baseline CD4+ cells/µL* CD4+ cells/µL * Response in Plasma Mortality Comments Program stage, treatment Response HIV RNA copies/mL* Abstract No. (No. Patients) Log10 Copies Duration of follow up experience HIV RNA/mL*

Efavirenz- vs 9 countries in southern Africa, nRTI + efavirenz 37.0 y, efavirenz: 60% female, Efavirenz 146 (mean) Data not In multivariate analysis Data not Low adherence, low baseline CD4+ Nevirapine-based ART Private-sector Aid for AIDS (64.6%) nevirapine: 68% female, Nevirapine 167 (mean) presented controlling for adherence, presented count, and high baseline plasma HIV Regimens: Adherence and Disease Management Program antiretroviral treatment-naive hazard ratio for time RNA levels correlate with decreased vs >5.0 efavirenz: 61% Virologic Outcomes Jan 1999-Mar 2003; to virologic failure after time to virologic failure nRTI + nevirapine >5.0 nevirapine: 55% initial suppression was Abstract 33 median, 2.2 y (35.4%) Results could be due to efavirenz 0.72 (0.59-0.88) for superiority or unmeasured (n=2821) efavirenz vs nevirapine confounders

Determinants of Mortality Uganda, Global AIDS Program Nevirapine/lamivudine/stavudine Median 38.0 y, 73% female, 127 (median) Data not Data not presented Defined early mortality as <_ Significantly more deaths from among HIV-infected Median, 2 y (96%) 39% WHO Stage III or IV, presented 3 mos, 16.4 per 100 person- wasting in 0-3 mos Individuals Receiving Home- Efavirenz/lamivudine/stavudine antiretroviral treatment-naive 5.3 (median) years Most common conditions based ART in Rural Uganda (4%) Mortality decreased in each contributing to death in first 3 mos Abstract 34 (n=1120) time period to 1.3 per 100 were: no diagnosis, Tb, cryptococcal person-years from 18-24 mos disease, o/p candida Baseline factors associated with mortality: CD4+ count 50-199 cells/ µL, Hgb <_ 10g/dL, BMI < 18 kg/m2, prior Tb, and depression index score

Variability in Populations Ethiopia, Kenya, Mozambique, Majority on stavudine/lamivudine/nevirapine, 58% female (of those on 104-198 At 6 mos: 246 No data available Mortality varied from 5% in The proportion of patients lost Enrolled and Their Outcomes Nigeria, Rwanda, South Africa, except South Africa: stavudine/lamivudine/ antiretrovirals), antiretroviral (range, 223-290) Rwanda, Mozambique, and to follow up, without active in HIV Care and Treatment Tanzania, ICAP-supported, efavirenz (86%) treatment-naive Tanzania to 15% in individual case-finding, ranged from 1% in HIV RNA n.a. At 12 mos: 291 Programs Across Countries in PEPFAR-funded (n=116,284 total; 71,482 on antiretrovirals) (range, 277-305) sites in Mozambique and Rwanda to 17% in Kenya Sub-Saharan Africa Sep 2004-Jun 2006 Ethiopia (without active case 98% of adult and 93% of children Abstract 534 finding) remained on first-line regimens

Clinical Outcomes and South Africa, government- Stavudine/lamivudine/efavirenz (37%) Median 32 y, 70% female, 44 (median, 2001-2002) At 3 years: At 3 years: Mortality at 6 mos (year of Determinants of mortality: initial Emerging Challenges after sponsored program Stavudine/lamivudine/nevirapine (43%) 90% WHO Stage III and IV, and 422 80% with <400 antiretroviral start): CD4+ count < 50 cells/µL, WHO 5 Years of ART in a South antiretroviral treatment-naive (median) stage IV disease, Kaposi’s sarcoma 2001-mid-2006 (n=2565) 99 (median, 2005) 12.4% (2001) African Township 5.4% (2005) at any point HIV RNA n.a. Abstract 535 Proportion remaining in care at 14% started second-line therapy by 54 mos: 78% 48 mos

Field Effectiveness of HAART Côte d’Ivoire, PEPFAR- Stavudine/lamivudine/nevirapine (50%) 34 y, 71% female, 77% WHO 116 (median) At 6 mos: +136 No data available 12-mo survival probability Lost to follow up at 12 mos: 19% in HIV-infected Adults in West sponsored Stavudine/lamivudine/efavirenz (22%) Stage III or IV, antiretroviral HIV RNA n.a. At 12 mos: +163 (baseline CD4+ count): Factors associated with mortality: Africa: The Aconda/ISPED/ treatment-naive At 18 mos: +213 < Mar 2004-Aug 2006 Zidovudine/lamivudine/efavirenz (21%) 77% (_ 50 cells/µL) baseline CD4+ count <50 cells/µL, EGPAF Program, Abidjan, Côte (in those still on 86% (51-100 cells/µL) male sex, older age, low baseline d’Ivoire 2004-06 (n=7862) treatment) 89% (101-150 cells/µL) Hgb, baseline BMI <18.5 kg/m2, Abstract 541 93% (>150 cells/µL) baseline WHO stage III or IV, care center

Catalyzing the Care and Botswana, Uganda, Lesotho, First-line therapy with zidovudine/lamivudine/ 5.1-7.8 y (mean), 50% female, Botswana: Botswana: Botswana: Botswana: crude mortality Botswana at 2.5 y: Treatment of HIV-infected Swaziland, and Malawi, nevirapine 50%-92% with WHO Stage III CD4+ percentage: 15 (n=880) at 6 mos: 79% <400 of entire clinic (on and off 10% switched to second or third- Children in Sub-Saharan joint Baylor, CDC, industry (n=5151) or IV, antiretroviral treatment- 0%<400 copies/mL at 6 mos: +27% at 12 mos: 81% <400 antiretrovirals): line treatment Africa: Early Outcomes from foundations, and government- naive at 12 mos: +30% at 36 mos: 71% <400 2003: 4.7% 93% alive and on treatment 5 Baylor College of Medicine sponsored at 36 mos: +32% 2004: 2.1% Centers Dec 2001-Jan 2007 Uganda: Uganda: 2005: 1.1% Abstract 79 CD4+ percentage: 8 at 6 mos: +18% 2006: 0.3% HIV RNA n.a. at 12 mos: +23% at 24 mos: +26%

Outcomes of Adults Receiving 22 countries in Africa, Asia, 91% had first-line stavudine/lamivudine/ Median, 35 y, 57% female, At first-line antiretroviral At 6 mos: + 91 No data available At 6 mos: ~7% died At 5.0 mos: 6% lost to follow up Second-line ART in Médecins and Central America, MSF- nevirapine at first-line antiretroviral initiation: (median) Probabilities of survival (death Factors associated with progression to Sans Frontières-supported supported programs 47% had second-line nelfinavir-based, 46% initiation: 87% WHO Stage III 63 (median), and at At 12 mos: +113 plus lost to follow-up): death: CD4+ nadir <50 cells/µL Projects in Resources-limited or IV, included only patients antiretroviral switch: Median time from antiretroviral had second-line lopinavir/ritonavir-based (median) At 6 mos: 0.91 Authors’ speculation: low rate of Countries initiation to switch 20 mos, 59% had didanosine-containing entering program who were 99 (median) antiretroviral treatment-naive At 12 mos: 0.86 second-line therapy use may be due to Abstract 35 median follow-up post-switch (n=352, 0.4% of adults initiating antiretroviral lack of availability, provider hesitation was 7 mos treatment with MSF since 2001) 4.64 (for those available) due to clinical status

BMI indicates body mass index; CDC, Centers for Disease Control and Prevention; HAART, highly active antiretroviral therapy; Hgb, FAR, United States President’s Emergency Plan for AIDS Relief; TB, Tuberculosis; WHO, World Health Organization. *CD4+ counts and HIV hemoglobin; ICAP, International Center for AIDS Care and Treatment Programs; MSF, Médecins Sans Frontières; n.a., not available; PEP- RNA are in units stated unless indicated otherwise. 62 International AIDS Society–USA Topics in HIV Medicine

adults and 272 cells/μL (CD4+ cell per- therapy in 2 treatment centers in Kam- included in the study; the median age centage, 8.6) in children; mean plas- pala, Uganda. The median age of par- was 35 years, 62% were female, and ma HIV-1 RNA level at baseline was ticipants was 36 years, median CD4+ the median follow-up time was 6.2

5.3 log10 copies/mL in both children count was 175 cells/μL, and 70% were months. Some 55.7% had “good” ac- and adults. Nevirapine or zidovudine female. The majority of the patients cess to the clinic, defined as living less had been used for PMTCT in 21 of the (83.8%) were receiving NNRTI-based reg- than 40 kilometers away. Probability adults and 9 children. Children were imens. Adherence was assessed by self- of remaining alive and in care at 15 almost twice as likely as adults to have report using semistructured quantitative months without active case-finding plasma HIV-1 RNA above 2.6 log10 cop- and unstructured qualitative interviews. was not statistically significantly dif- ies/mL (26% vs 14%, respectively; Ninety-four patients (13.7%) had at least ferent between the 2 time periods P = .0001). Predictors of virologic fail- 1 episode of discontinuation (defined as (HR, 1.1; 95% CI, 1.0-1.2). Multivari- ure in children were male sex (odds simultaneous discontinuation of all an- ate analysis revealed several factors ratio [OR], 2.54; 95% CI, 1.18-5.57), tiretroviral drugs for at least 1 month). associated with remaining in care, in- CD4+ percentage below 5 (OR, 3.99; There were 175 patients (25.5%) who cluding female sex (HR, 1.2; 95% CI. 95%CI, 1.75-9.07), and initial antiret- reported modifying therapy by chang- 1.1-1.3; P = .003), good access to the roviral regimen of stavudine/lamivu- ing or switching at least 1 antiretroviral clinic (HR, 1.5; 95% CI, 1.3-1.8; P < dine/nevirapine versus zidovudine/la- medication. The most common reason .001), and treatment paid by a funding mivudine/efavirenz (OR, 3.33; 95% for discontinuation was drug cost (43%), program or employer (HR, 3.6; 95% CI, 1.51-7.36). The same initial anti- and for modification was avoidance of CI, 2.2-6.0; P < .001). The investiga- retroviral regimen predicted failure in adverse events (71.8%). In a multivari- tors found that mean enrollment per adults. ate logistic regression analysis adjusting month increased significantly with Nkengasong and colleagues (Ab- for baseline parameters, factors associ- the decrease in antiretroviral cost: stract 729) analyzed data from 134 ated with discontinuation were duration 46.5 persons enrolled per month in children receiving their first antiret- of antiretrovirals of less than 1 year (OR, the first time period and 95.5 persons roviral treatment regimen between 11.11; 95% CI, 5.00-25.00), year of ini- per month in the second (P < .001). August 1998 and September 2003 in tiation being 2004 or earlier (OR, 4.42; Nachega and colleagues (Abstract Côte d’Ivoire. At baseline, the median 95% CI, 1.90-10.47), prior antiretroviral 548) performed an analysis of direct age was 7 years, 80% of the children experience (OR, 3.70; 95% CI, 2.13- health care costs associated with pa- had a CD4+ percentage of below 15, 6.25), history of hospitalization (OR, tient demographic characteristics, and the median plasma HIV-1 RNA 2.36; 95% CI, 1.32-4.20), and use of al- baseline CD4+ cell count, and level level was 5.6 log10 copies/mL. After 1 ternative medicines (OR, 2.18; 95% CI, of antiretroviral adherence as deter- year of antiretroviral therapy, 54% of 1.06-4.47). Modification was associated mined by pharmacy claims data in children had an undetectable plasma with duration of therapy more than 3 5455 HIV-1-infected adults initiating HIV-1 RNA and cumulative probability months (OR, 3.13; 95% CI, 1.16-8.33), NNRTI-based antiretroviral therapy of developing any class of drug resis- year of initiation being 2004 or less (OR, in southern Africa between 1998 and tance was 0.44 (95% CI, 0.35-0.53). 2.10; 95% CI, 1.02-4.31), being married 2003. The cohort had a mean age of The magnitude of the virologic re- (OR, 0.61; 95% CI, 0.37-0.98), and low 37.1 years, and was 59.6% female. sponse was associated with emergence regimen pill burden (OR, 0.04; 95% CI, Mean baseline CD4+ count was of drug resistance, as were smaller in- 0.02-0.08). 152.6 cells/μL and the mean follow-up creases in CD4+ count from baseline, Mosoko and colleagues (Abstract period was 27.3 months. The investi- and dual-drug regimens. 536) used a retrospective cohort analy- gators noted a statistically significant sis to examine adherence to antiretrovi- dose-response relationship between Adherence in ral therapy and loss to follow up during nonantiretroviral therapy-related Resource-limited Settings 2 time periods in Limbe, Cameroon. health expenditures (eg, consulta- The investigators compared data for tions, hospitalizations, investigations, Although the need for strict adherence patients before and after October 2004, and other than antiret- to antiretroviral medications is well when the government reduced the cost rovirals) and adherence. In those pa- documented in the literature, factors of antiretrovirals from approximately tients whose adherence rate was 95% affecting antiretroviral treatment dis- US $30 per month to US $6 per month. or higher, nonantiretroviral therapy continuation and modification in re- The annual gross domestic product per costs were US $152 per month (95% source-limited settings are not well de- capita in Cameroon is US $2400 (2006 CI, 146-157), and in those with lower scribed. Three abstracts took different estimate), but the population served than 50% adherence, costs were US approaches to adherence evaluation in by the clinic is highly economically $200 per month (95% CI, 189-211). Africa. disadvantaged and costs for antiretro- Total monthly health care costs de- Kiguba and colleagues (Abstract viral therapy remain a large portion of creased with time on antiretroviral 530) conducted a cross-sectional study household income even after the price therapy by approximately US $9 per of 686 individuals on antiretroviral reduction. A total of 2920 patients were month. Poor adherence, low baseline

63 Conference Highlights - Advances in Antiretroviral Therapy Volume 15 Issue 2 April/May 2007

CD4+ cell count, older age, and black rologic failure in multivariate analysis per that was sent to Holland every 3 race were all associated with higher to- were CD4+ count below baseline with weeks for RNA extraction and testing tal expenditures. a fall of greater than 30% from the using a real-time reverse transcrip- peak value achieved on antiretroviral tase PCR assay with a lower limit of

Laboratory Monitoring in treatment (OR, 3.7; 95% CI, 1.4-9.4, detection of 2.7 log10 copies/mL. Us- Resource-limited Settings P = .007) and any treatment inter- ing the local testing as the gold stan- ruption of more than 2 days (OR, 3.6; dard, the whole-blood filter-paper Plasma HIV-1 RNA measurements are 95% CI, 1.7-7.4, P = .001). A failure transfer assay had a sensitivity of frequently unavailable in resource- score was then developed using these 86% (99% CI, 67-100), a specificity limited countries and low-cost sur- 2 parameters with 1 point for each of 77% (99% CI, 69-85), a negative rogates for virologic response would parameter. If both parameters were predictive value of 27% (99% CI, 14- be a great benefit to monitoring anti- absent (score=0) the test had a sen- 40), and a positive predictive value of retroviral therapy in these settings. In sitivity of 57% (95% CI, 42-71), speci- 98% (99% CI, 95-100). The plasma an attempt to predict virologic failure ficity of 81% (95% CI, 77-84), a posi- filter paper transfer assay showed with CD4+ count change, Wood and tive predictive value of 25% (95% CI, improved performance, with a sen- colleagues (Abstract 538) examined a 17-34), and negative predictive value sitivity of 100% (99% CI, 84-100), cohort of 161 patients receiving anti- of 95% (95% CI, 91-96) for predict- specificity of 99% (99% CI, 97-100), retroviral therapy in Capetown, South ing plasma HIV-1 RNA below 2.6 log10 negative predictive value of 95% Africa, who had experienced at least copies/mL. Applying this monitoring (99% CI, 77-99) and positive predic- 1 episode of virologic failure, defined algorithm to the cohort, 112 patients tive value of 100% (99% CI, 98-100) as a single episode of plasma HIV-1 would have had a failure score of 1 or 2 compared with the local gold stan-

RNA above 3.0 log10 copies/mL follow- and been assigned to virologic testing, dard. Filter paper transfer of plasma ing a first plasma HIV-1 RNA of below and 384 would have been assigned as specimens could be a reliable means

2.6 log10 copies/mL. Risk of virologic score of 0 and not tested, resulting in of virologic testing in resource-limit- failure was independently associated 21 missed failures. ed settings. Whole-blood filter-paper with baseline CD4+ count (relative Iqbal and colleagues (Abstract transfer testing was limited by a high risk [RR] 2.48; 95% CI, 1.07-5.74, P = 673) compared the performance of a number of false-positive results. .04) and with CD4+ count increases non-nucleic acid-based plasma HIV-1 Dried blood spots are used in re- of less than 100 cells/μL during follow RNA assay to a gold standard nucle- source-limited settings as an alter- up (RR, 2.54; 95% CI, 1.01-6.43, P = ic acid-based assay on 121 plasma native to plasma for drug resistance .03). However, a negative CD4+ count specimens from 107 HIV-1 subtype testing. Masciotra and colleagues slope in values 3 to 2 months prior to C-infected patients. The sensitivity of (Abstract 629) evaluated the level of failure had a sensitivity for detecting the non-nucleic acid-based assay to concordance between resistance de- virologic failure of only 55.3% (95% detect HIV-1 RNA below 2.6 log10 cop- tected in plasma versus dried blood CI, 47.2-63.1), a specificity of 61.5% ies/mL (equivalent to <5500 copies/ spot. Specimens from 60 patients (95% CI, 59.6-63.3), a positive predic- mL) was 100%. The difference seen infected with HIV-1 subtype B virus tive value of 7.8% (95% CI, 6.3-9.5), in the non-nucleic acid-based assay were collected, and successfully RNA and a negative predictive value of compared with standard polymerase genotyped in 50 patients. There was 95.9% (95% CI, 94.8-96.8) indicating chain reaction (PCR) was a decrease good correlation between plasma and that change or negative slope in CD4+ of 0.23 log10 copies/mL (95% CI, dried blood spot identification of re- cell count was a poor predictor of viro- −0.91-0.45). This study suggested sistance mutations with dried blood logic failure. that this less expensive and techni- spot detecting 97% (306 of 316) of Meya and colleagues (Abstract 531) cally simpler method should be eval- mutations identified in plasma, and expanded on the above strategy in a uated further as a substitute for cur- plasma detecting 95% (306 of 322) cross-sectional study of 496 patients rent plasma HIV-1 RNA tests. of mutations identified in dried blood in Uganda on NNRTI-based antiretrovi- Waters and colleagues (Abstract spot. A majority of discrepancies ral regimens. They searched for treat- 674) conducted an analysis of filter were secondary to mixtures contain- ment, adherence, clinical, and labo- paper transfer of whole blood and ing minor protease position altera- ratory parameters that could predict plasma samples from resource-limit- tions and unusual amino acids substi- virologic failure, defined as a plasma ed settings to a European laboratory tutions in reverse transcriptase. Only

HIV-1 RNA level above 2.6 log10 cop- for plasma HIV-1 RNA determinations 2 major mutations were absent in ies/mL. The cohort was 65% female in patients on antiretroviral therapy. dried blood spots (M46L and K103N). and had a median age of 38 years, Blood samples from 402 patients in In this small study, dried blood spots and 63% were on a nevirapine-based Uganda underwent local testing using appeared to be a feasible and reliable regimen. One hundred and seventeen a standard reverse transcriptase PCR- alternative to plasma for resistance patients had plasma HIV-1 RNA above based assay. Blood droplets were si- mutation detection in resource-lim- 5 2.6 log10 copies/mL. Predictors of vi- multaneously transferred to filter pa- ited settings (see also ). 64 International AIDS Society–USA Topics in HIV Medicine

Prevention of Maternal-to-child child health care, incorporation of non- the DREAM study, costs for infections Transmission professional trained birth attendants averted and Disability Adjusted Life into PMTCT programs, recognition of Years (DALY) saved were calculated Bulterys presented an overview re- PMTCT as a crucial entry point to care according to the Joint United Nations garding the status of PMTCT and the for HIV-seropositive women and their Programme on HIV/AIDS (UNAIDS) reasons it continues to be inadequate families, and improvement of linkages guidelines for intervention evaluation in resource-limited settings (Abstract between PMTCT and long-term anti- (Abstract 762). Of 6175 pregnant wom- 11). Rates of maternal-to-child trans- retroviral services are key strategies to en who received antenatal HIV testing, mission (MTCT) of HIV without inter- decrease rates of MTCT. The following 1862 tested HIV seropositive; 1594 of vention are 15% to 45% but can be abstracts reported on current efforts these HIV-seropositive pregnant wom- reduced to 1% using antiretroviral and barriers to decreasing MTCT. en entered the program. The majority prophylaxis, caesarian delivery, and of program costs were spent on labo- avoidance of breastfeeding. In indus- Antiretroviral Prophylaxis for ratory analyses (30%), medications trialized nations, these interventions Prevention of Mother-to-Child (24%), and personnel (21%). Infection have been successful at reducing rates Transmission Among Women Ineligible rates at 1 month and 6 months were of MTCT to around 2% or less but in for Antiretroviral Treatment 3.8% and 1.5%, respectively, resulting resource-limited settings, particularly in an estimated 481 averted infections. sub-Saharan Africa, rates of MTCT In the Drug Resource Enhance- The efficacy of the intervention was remain close to rates without inter- ment against AIDS and Malnutrition calculated to be 68.53% avoided infec- vention. According to United Nations (DREAM) protocol, all HIV-seroposi- tions through 6 months postpartum, International Children’s Emergency tive pregnant women received potent with a calculated cost of US $518 per Fund (UNICEF) global estimates for antiretroviral therapy predelivery and infection averted and US $22 per DALY 2005, there were 21 million HIV-sero- postpartum regardless of virologic saved. Subtracting the cost of care for positive pregnant women worldwide, and immunologic status. In Abstract HIV-seropositive children (US $369 per of whom only 22% were identified as 747, outcomes of 341 HIV-seroposi- HIV-seropositive child), cost per infec- infected during pregnancy or delivery; tive women in Mozambique from the tion was US $149 per infection averted 10% of mothers received antiretroviral DREAM study who received triple- and US $6 per DALY saved. This study prophylaxis and 8% of HIV-exposed antiretroviral prophylaxis for PMTCT showed that PMTCT with potent anti- infants received antiretroviral prophy- with either zidovudine/lamivudine/ne- retroviral prophylaxis is cost-effective. laxis. Bulterys suggested that PMTCT virapine or stavudine/lamivudine/nevi- Additional benefits not reflected in this continues to fail in resource-limited rapine at 25 weeks gestation through analysis include decreasing the num- settings. Lack of resources is a key 6 months postpartum were presented. ber of orphans by increasing the life limitation to successful PMTCT, and At baseline, mean age, CD4+ count, expectancy of the mother, supporting includes inadequate antenatal care viral load, and percent in clinical class the health sector by training of local infrastructures, limited availability of WHO stage III to IV were 26 years, 422 personnel, and decreasing stigma by rapid HIV test kits and antiretroviral cells/µL, 3.94 log10 copies/mL, and 6, improving the quality of life of HIV- medications, a disconnection between respectively. Median time of antiret- seropositive adults and their families PMTCT programs that identify HIV-se- roviral therapy predelivery was 87 thereby facilitating other HIV and AIDS- ropositive pregnant women and their days. At 1 month postpartum, 4 of 341 related public health interventions. families and programs that provide (1.2%) infants tested were HIV sero- long-term HIV care and antiretroviral positive and at 6 months an additional Antiretroviral Treatment of HIV- therapy, and competing health pri- 2 of 251 (0.8%) infants tested were seropositive Pregnant Women orities in the face of decreasing health HIV seropositive (98 infants were not care resources. Lack of access to clean yet 6 months old and 8 infants were Providing long-term potent anti- water and good alternatives to breast- lost to follow up). Seven infants died, retroviral therapy for eligible HIV-se- feeding counteract decreased rates of all of whom were HIV seronegative at ropositive women is an important HIV transmission in resource-limited 1 month (mortality rate 28.5% child- global public health initiative both for settings due to increased rates of mor- years). Risk of MTCT was not associat- the women who require antiretroviral tality in formula-fed infants (see “HIV ed with baseline CD4+ count or viral drugs and for PMTCT. The following Epidemiology and Prevention Inter- load. There was a trend of decreased studies evaluated outcomes among ventions” in this issue). Bulterys con- transmission among women with lon- women who initiated antiretroviral cluded that the United Nations goal to ger predelivery exposure to antiretrovi- therapy during pregnancy. decrease new HIV infections globally rals (129 days among nontransmitters The DART study is a randomized by 50% can be met but only by radi- vs 79 days among transmitters) but trial of antiretroviral-monitoring strat- cally increasing access to and imple- the difference was not statistically sig- egies among adults with symptomatic mentation of PMTCT. He suggested nificant (P = .58). HIV infection and CD4+ counts below that full integration of maternal and In a cost-effectiveness analysis of 200 cells/µL in Uganda and Zimbabwe

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(Abstract 746). Outcomes of 221 preg- nonadherence, neither of which were men (n=34); 1 woman on a salvage nancies in 198 women were assessed assessed in this study. regimen was not included. Women over a median follow-up period of 2.4 who had prior history of antiretroviral years. Median CD4+ count was 115 Suppression of HIV-1 RNA During therapy had a longer time to achieving cells/µL and 18% were WHO Stage IV Prevention of Mother-to-Child virologic suppression than did women at baseline. Most of the women were Transmission with no prior history of antiretroviral on a regimen of zidovudine/lamivu- therapy (58 vs 34 days, respectively). dine plus tenofovir (70%), nevirapine The European Collaborative Study is a Adherence based on pharmacy records (15%), or abacavir (4%). Among the cohort of HIV-1-infected pregnant wom- correlated with proportion of patients 164 women with a known outcome en and their infants from 10 European achieving virologic suppression: 90.2% there were 91 live births (55%), 11 countries (Abstract 758). An analysis of of patients who had virologic suppres- stillbirths (7%), and 62 terminations time to virologic suppression was con- sion had “excellent adherence” com- (38%). No infants were diagnosed ducted in 240 women from this cohort pared with 54.5% of patients who did with HIV infection. Four of the wom- who had their initial diagnosis of HIV not achieve virologic suppression. en died and 3 infants had congenital during pregnancy or documented non- abnormalities. This is the largest data receipt of prior antiretroviral therapy. All Antiretroviral Prevention of Mother- set on in utero exposure to triple an- women received potent antiretroviral to-Child Transmission: Effects on tiretroviral therapy in resource-limited therapy; 156 (65%) initiated a PI-based Resistance in Mothers and Infants settings, the only data set evaluating in regimen (80% nelfinavir) and 84 (35%) utero exposure to tenofovir to date, and initiated a nevirapine-based regimen. Coffie and colleagues (Abstract 93LB) is reassuring given the absence of peri- Fifty-nine percent were black, 90% presented a prospective cohort study natal transmission detected and rates were born in Africa, and 64% were di- of 247 women in Côte d’Ivoire with at of congenital abnormalities similar to agnosed with HIV during pregnancy. At least 1 prior pregnancy who initiated other studies. Analysis of maternal and time of delivery, 73% achieved virologic antiretroviral treatment with stavudine infant outcomes is ongoing. suppression. Antiretroviral regimen did or zidovudine plus lamivudine plus ne- A prospective study of HIV-seroposi- not correlate with virologic suppression virapine or efavirenz. Virologic and im- tive, antiretroviral-naive (aside from but time to undetectable HIV-1 RNA was munologic responses were evaluated prior single-dose nevirapine for PMTCT) faster among patients on a nevirapine- 12 months after initiation. Eighty-six pregnant women with CD4+ counts based regimen (HR, 1.54), who had women had previous exposure to sin- below 350 cells/µL was conducted at a country of origin in West Africa (HR, gle-dose nevirapine and short-course a prenatal care clinic in Mozambique 1.90), and whose baseline HIV-1 RNA zidovudine with lamivudine for PMTCT,

(Abstract 756). Antiretroviral therapy was below 3.81 log10 copies/mL (HR, 52 had previous exposure to single- with nevirapine/lamivudine plus zid- 2.76). Among women with baseline dose nevirapine and short-course zid- ovudine or stavudine was initiated 3 CD4+ count below 250 cells/µL, 82.4% ovudine, and 109 women had no his- weeks after enrollment and continued on nevirapine-based regimens achieved tory of antiretretroviral exposure for until at least 6 months postpartum. In- virologic suppression at 8.5 weeks com- PMTCT. Of women who received ne- fants were given single-dose nevirap- pared with 50.4% on PI-based regimens. virapine plus zidovudine/lamivudine, ine within 48 hours of delivery. Of 163 Faster time to virologic suppression may 11 of 73 had baseline resistance to la- women who enrolled in the study, 148 have been due to the suboptimal effica- mivudine (15.1%) and 3 of 70 (4.3%) received antenatal antiretroviral thera- cy of non-boosted PI nelfinavir pharma- had baseline resistance to nevirapine. py and 146 were followed up through cokinetics during pregnancy leading to Sixteen of 42 (38.1%) in the nevirap- delivery. These 146 women delivered subtherapeutic levels, or nonadherence ine plus zidovudine group had baseline 149 infants, of whom 17 died prior to in the PI group, neither of which were resistance to nevirapine. Neither group HIV testing and 26 were not tested. assessed. Faster virologic suppression had evidence of zidovudine resistance. Seven of 106 (6.6%) tested infants among women from West Africa may The overall rate of virologic failure (HIV- were HIV-1 seropositive. Maternal and have been the result of differences in 1 RNA > 500 copies/mL) at 12 months infant characteristics, including mater- HIV-1 subtype or host biologic or genetic was 19% (42 of 219). Fifty percent of nal baseline CD4+ count, HIV-1 RNA differences. women with baseline lamivudine re- viral load, duration of antiretroviral In a retrospective cohort of 114 sistance had failure, compared with therapy, and feeding strategy did not women and infant pairs exposed to po- 18.9% of women exposed to lamivu- correlate with perinatal transmission. tent antiretroviral therapy in Vancouver, dine but with no evidence of baseline This relatively high rate of perinatal British Columbia (Abstract 759), 80% resistance. Among women with base- transmission in the setting of potent of women had achieved virologic sup- line nevirapine resistance 27.8% had antiretroviral therapy could have re- pression at time of delivery with no dif- failure, compared with 18.6% among sulted from subtherapeutic concen- ference in probability of suppression women exposed to nevirapine but with trations of antiretroviral drugs in the between women on a PI-based regimen no evidence of baseline nevirapine setting of pregnancy and nursing or (n=57) versus an NNRTI-based regi- resistance. Women with no history of

66 International AIDS Society–USA Topics in HIV Medicine

antiretroviral exposure for PMTCT had was conducted in samples from 29 in- trations of antiretrovirals and presence a 16% rate of virologic failure. In multi- fants. Four of 16 infants infected in utero of major resistance mutations. Duration variate analysis, baseline CD4+ count and 4 of 13 infants infected intra-peri- of antiretroviral prophylaxis was differ- below 200 cells/µL, baseline lamivudine partum had evidence of nevirapine re- ent between patients with and without resistance and, especially, poor adher- sistance. The 2 infants infected in utero major mutations (119 days vs 62 days, ence were associated with virologic fail- who had wild-type virus received single- respectively, P = .0002). Given the evi- ure with ORs of 0.34, 6.86, and 12.68, dose nevirapine at birth but their moth- dence that avoidance of breastfeeding respectively. PMTCT-acquired lamivu- ers did not receive nevirapine. Infants for PMTCT is not a viable option for dine resistance was associated with infected in utero who had resistance women in living in resource-limited poorer 12-month virologic outcomes. mutations had a mixture of mutant and settings (see “HIV Epidemiology and However, time of initiation and dura- wild-type virus, whereas infants infect- Prevention Interventions” in this issue), tion of antiretroviral therapy may have ed intra-peripartum had either 100% the utility of antiretroviral therapy to confounded the outcomes in the lami- resistant virus or 100% wild type. The prevent postnatal transmission requires vudine group, as time to initiation of dichotomy of virus (all resistant or all further evaluation. antiretroviral therapy post-PMTCT was wild type) among infants infected intra- shorter among the lamivudine-exposed peripartum might result in persistent Antiretroviral Drug Resistance group than in women who received nevirapine resistance among infants in- PMTCT prophylaxis without lamivudine fected with mutant strains. In contrast, Transmitted Drug Resistance (median 15 months vs 28 months), and the mixture of resistant and wild-type time of exposure to antiretrovirals dur- virus in infants infected in utero could Epidemiology of Transmitted Drug ing PMTCT prophylaxis was longer in result in a better chance of reversion to Resistance. Rates of transmitted drug the lamivudine-exposed group (median wild type. The high mortality associated resistance (TDR) in Europe, Australia, 56 days vs 30 days). with in utero infection indicates a need and the United States range from 11% A study of infants born to HIV-sero- for earlier treatment. However, the high to 15% among patients with primary positive women in Mozambique (Ab- rates of nevirapine resistance in this HIV-1 infection and 7% to 11% among stract 92) compared rates of NNRTI re- group would require a non-nevirapine- patients with newly diagnosed HIV-1 sistance among infants infected in utero based regimen. This study is ongoing in whom time of infection is unknown (HIV-1-seropositive by PCR at birth up and will assess rates of MTCT through (Abstract 60). Data from 11 states in to 2 weeks postpartum) with rates breastfeeding and whether resistance the US Variant, Atypical, and Resis- among infants infected intrapartum or mutations fade over time. tant HIV Surveillance group (VARHS) early postpartum (HIV-1-PCR-positive 2- were analyzed to estimate the preva- 8 weeks postpartum). Standard of care Antiretroviral resistance in breast lence of TDR and distribution of sub- for PMTCT in this setting is initiation milk. In a study of PMTCT among 40 types (Abstract 648). Specimens from of potent antiretroviral therapy in all HIV-seropositive pregnant women in 3130 antiretroviral-naive individuals, HIV-seropositive pregnant women with Mozambique who received zidovudine/ newly diagnosed with HIV-1 infection CD4+ counts below 350 cells/µL, and lamivudine/nevirapine at 28 weeks ges- from March 2003 to October 2006 short-course zidovudine at 34 weeks tation through 4 weeks postpartum, lev- were analyzed, and 10.4% had virus gestation followed by single-dose nevi- els of HIV-1 RNA and resistance patterns with drug resistance mutations. Resis- rapine in the mother at labor and in the were evaluated in the first week after tance to NNRTIs, nRTIs, and PIs were infant at birth for HIV-seropositive preg- delivery (Abstract 764). Major resistance present in 6.9%, 3.6%, and 2.4%, nant women with CD4+ counts above to NNRTIs and lamivudine were present respectively, and 1.9% had multi- 350 cells/µL. Data for 330 infants who in plasma of 3 of 40 (7.5%) and 1 of 40 class resistance. Predominant muta- have enrolled thus far were presented. (2.5%) women, respectively. Similarly, tions were K103N for NNRTI (70.1%), Twenty-two of 330 infants (6.7%) were NNRTI and lamivudine resistance muta- M41L for nRTI (45.1%), and L90M for infected in utero (7 have died, 8 are lost tions were present in virus in the breast PIs (40.0%). Non subtype B or recom- to follow up, and 7 continue follow up), milk of 7.5% and 5% of women, re- binant forms were found in 5.1% of 14 of 199 infants (7.0%) were infected spectively. Although prevalence of resis- patients. peripartum (excluding infants who were tance was similar in plasma and breast Two large intervention studies HIV-1 seronegative at birth but status at milk, patterns of resistance were differ- that recruited HIV-seronegative MSM 8-week follow up was unknown) and in ent in these compartments indicating evaluated the prevalence of drug re- 131 of 330, HIV status at birth was un- that although some HIV-1 in breast milk sistance among men who seroconver- known. Six-month mortality of infants is derived from diffusion from plasma, ted during study participation. In the infected in utero and intra-peripartum it is likely that local viral production EXPLORE study (Abstract 650), men was 6 of 16 (37.5%) and 0 of 6 (0%), also contributes to the HIV-1 population were randomized to a behavioral in- respectively. Oligonucleotide ligation present in breast milk. In plasma and tervention to prevent HIV-1 acquisi- assay specific for detecting the NNRTI breast milk there were no correlations tion. Two hundred and fifty-nine men mutations K103N, Y181C, and G190A between level of HIV-1 RNA or concen- seroconverted and 195 had genotyp-

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ing results available for analysis. A population may be a factor. Sentinel- (93 of 913) (Abstract 60). There was total of 15.9% (31 of 195) had resis- site surveillance in STD clinics and HIV no statistically significant difference tance mutations, 3.6% had multi-class testing facilities in San Francisco (Ab- in baseline HIV-1 RNA level in patients resistance, and 5 men had CXCR4- stract 652) showed that rates of TDR with TDR compared with patients tropic virus. In multivariate analysis, remained stable from 2004 to 2006 with susceptible virus, but when strat- there was no association between with an overall rate of 13.7% (55 of ified by resistance class, individuals resistance and demographic, clini- 402). Whether these trends continue with NNRTI resistance had a baseline cal, or risk-factor data. In the gp120 and will be similar in other cohorts re- HIV-1 RNA level of 0.4 log10 copies/mL vaccine efficacy trial (in which gp120 quires further evaluation. higher than patients with susceptible was found ineffective in prevention virus (P = .003). Patients with nRTI of HIV infection), 5095 HIV-seronega- Natural History of Transmitted Drug resistance had a mean baseline HIV- tive MSM and 308 women at high risk Resistance. In the setting of second- 1 RNA level of 0.7 log10 copies/mL for HIV were enrolled, and 362 men ary drug resistance, it takes an average lower than patients with susceptible and 6 women seroconverted during of 12 to 16 weeks for a population of virus (P = .001). There was a trend the study (Abstract 653). Two hundred predominantly mutant virus to con- toward lower baseline HIV-1 RNA and eighty-six samples were avail- vert to majority wild-type virus after level in patients with PI-resistance able for sequencing, of which 16% removal of drug pressure. In the case mutations than in patients with sus- had at least 1 resistance mutation and of TDR, it takes an average of 3 years ceptible virus but the difference was 7% had multi-class resistance. In this or more for reversion to wild type, as not statistically significantly different. study, having an HIV-seropositive part- the mutant virus is not competing with These differences in viral load con- ner (OR, 4.6; 95% CI, 1.08-5.2, P = existing wild-type strains. Evaluating a tinued for patients with NNRTI- and .03), reporting unprotected anal sex group of 14 acutely infected HIV-1-se- nRTI-resistance mutations at 1 and (OR, 5.5; 95% CI, 1.3-14.9, P = .02) ropositive patients with TDR, Little and 3 years of follow up but the PI trend and marijuana use (OR, 4.0; 95% CI, colleagues (Abstract 60) determined disappeared. The clinical significance 1.02-4.2, P = .04) were independently the mean time to first appearance of of these differences in viral load is associated with TDR. a wild-type and resistant mixture to unclear and needs further confirma- Nambiar and colleagues (Abstract be 103 weeks (about 2.0 years; 95% tion in larger cohort studies. 657) found that TDR among individu- CI, 49-216 weeks). They subsequently Seven hundred and ninety-six pa- als with primary HIV-1 infection was evaluated mean time to last wild-type tients with recent HIV infection were associated with diagnosis of a sexu- and resistant mixture (ie, no evidence enrolled in AIEDRP DACS 002 from ally transmitted disease (STD) within of resistant virus) and found that 13 of 1995 to 2006 and received antiretro- 3 months of HIV diagnosis. The over- 14 patients had pure resistant virus or viral treatment within 7 months of the all rate of TDR was 15% (28 of 185) persistence of mixture; time to com- estimated date of infection (Abstract and of the 124 individuals screened plete reversion by population sequenc- 60). Of these patients 84 had TDR, for an STD, 45% were diagnosed with ing in the 1 patient that converted to and, compared with patients with an STD; 68% had TDR versus 31% wild-type virus was 2.7 years. These susceptible virus, there was no statis- with wild-type virus (P = .03). The au- patients continue to be followed up, tically significant difference in time to thors concluded that this correlation and at 4 years of follow up, many pa- reach HIV-1 RNA levels below 50 cop- between TDR and presence of an STD tients continue to have pure or mixed ies/mL. However, when evaluated by could have resulted from facilitated resistant virus. Mean replication capac- class, individuals with PI-resistance transmission of less fit virus through ity of the TDR virus was 87%, which mutations had a longer time to reach mucosal breakdown in the setting of was not statistically significantly differ- HIV-1 RNA levels below 50 copies/mL STDs or poor drug adherence among ent from reference wild-type virus. In than patients with susceptible virus HIV-seropositive individuals in the this cohort, detection of wild-type vi- (P = .002). This was likely due to the sexual networks of people engaging in rus after acquisition of TDR virus takes fact that from 1996 to 2000, resis- high-risk sexual behavior. an average of 2 years and complete re- tance testing was not routinely per- An analysis comparing cohorts of version to wild-type virus theoretically formed prior to antiretroviral therapy early acute, HIV-1-infected, antiret- might never occur. The high fitness dis- initiation and 50% of patients with roviral-naive individuals in 2003 to played by these TDR viruses may be baseline PI resistance were initiated 2004 and 2005 to 2006 in New York due to selected transmission of more on a PI-based regimen. Complete vi- City showed a decrease in TDR from fit resistant variants. ral suppression failed to occur in 45% 24.1% (27 of 112) to 12% (13 of 108), Among patients enrolled in the of patients (38 of 84), of whom 70% P = .02 (Abstract 651). The reason Acute Infection and Early Disease had fewer than 3 active antiretroviral for this decrease is unclear, although Research Program (AIEDRP) DACS medications in their regimen. The the authors hypothesize that better 003 study from June 1993 to January difference in time to suppression was drug adherence with less viral break- 2007, the rate of TDR among recently likely related to whether antiretrovi- through in the potential transmitter HIV-1-infected individuals was 10.2% rals to which the virus is susceptible

68 International AIDS Society–USA Topics in HIV Medicine

were used. Given the relatively high resistance mutations using standard, el >50 copies/mL) by 48 weeks, and rates of TDR in more developed set- population-based genotype-sequenc- 221 had suppressed viral loads (HIV-1 tings, the authors emphasized the im- ing versus allele-specific PCR among RNA level <50 copies/mL) within 48 portance of performing baseline re- 61 antiretroviral-naive pregnant wom- weeks. Using allele-specific PCR test- sistance testing on newly diagnosed, en enrolled in the WITS. M184V was ing for K103N, Y181C, and M184V, 9 antiretroviral-naive patients in these detected 1.5 times more frequently us- patients had low-frequency variants at areas, reaffirming current consensus ing allele-specific PCR than using stan- baseline, 7 of whom (78%) had viro- recommendations. dard genotype sequencing (13.3% vs logic failure. Five of 6 of the genotypes Low-frequency Resistance Variants. 8.8%, respectively); D30N was detect- available at failure had the same mu- Each HIV-infected patient is infected ed 3 times more frequently in using tations that were present at baseline. with a strain of HIV that, over time, allele-specific PCR than using standard One patient who experienced failure develops into a swarm of viruses con- genotype sequencing (6.7% vs 2.2%, within 2 months of treatment was taining different polymorphisms (ie, respectively). found to have dual-class resistance intra-patient viral diversity). Some of Each of these studies supports the (K103N, Y184V) at baseline. In logistic these polymorphisms are a result of conclusion that low-frequency resis- regression, presence of low-frequency the natural evolution of wild-type vi- tance mutations are missed by con- variants at baseline was associated rus, and other polymorphisms repre- ventional sequencing, but do these with virologic failure (OR, 11.0; 95% sent resistance mutations that carry low-frequency resistant variants carry CI, 2.2-58.8, P = .004), but baseline clinical significance. Conventional bulk clinical significance, as has been sug- viral load and baseline CD4+ count resistance testing detects resistant vari- gested in previous studies? Peuchant were not associated with virologic fail- ants that occur at a frequency greater and colleagues (Abstract 666) evalu- ure (P = .43 and P = .30, respective- than 20% above “background” wild- ated the effect of resistance detected ly). The authors concluded that there type polymorphisms. Low-frequency by conventional and sensitive resis- are clinical consequences to harboring resistance variants are populations tance testing on virologic and immu- low-frequency resistant variants and of resistant virus that occur at a fre- nologic outcomes. Of 172 antiretrovi- advocated for baseline sensitive test- quency that is below the level detect- ral-naive, recent HIV-1 seroconverters, ing, especially among antiretroviral- able by bulk sequencing but above the 9.3% had resistance to at least 1 class naive individuals. background wild-type polymorphisms. at baseline. Baseline resistance was Many studies have documented the related to a lower baseline HIV-1 RNA Global Perspectives on Antiretroviral existence of these low-frequency resis- level (3.76 log10copies/mL vs 4.59 log10 Resistance tance variants among individuals with copies/mL for resistant and wild-type virologic failure but have no evidence virus, respectively; P = .002), higher Schapiro (Abstract 59) presented an of resistance based on bulk-resistance baseline CD4+ counts (557 vs 425 overview of the impact of HIV-1 subtype testing (Abstract 61). Johnson and col- cells/µL for resistant and wild-type vi- on drug resistance. A majority of drug leagues (Abstracts 61, 639) used a real- rus, respectively; P = .03) and a less development and resistance data have time PCR detection assay to assess the steep decrease in viral load after 1 focused on HIV-1 subtype B, yet subtype prevalence of resistance among anti- month of treatment. In a substudy of B represents a minority of the infections retroviral-naive patients who had no 78 patients, they found no effect of the worldwide (10%); other subtypes and detectable resistance by conventional presence of low-frequency resistant circulating recombinant forms consti- sequencing and to evaluate the level mutants on virologic or immunologic tute the rest of infections worldwide.7 of baseline low-frequency resistance response to therapy. The authors were Furthermore, rates of non-subtype B in- among antiretroviral-naive patients unable to conclude that detection of fections are increasing in Europe and the with known resistance by conventional low-frequency resistant mutants cor- United States (Abstracts 630, 648). Sub- sequencing. They found that 15% (30 related with virologic or immunologic types differ in genetic variability, which of 205) of patients with wild-type vi- outcomes but the study was limited can lead to differences in response to rus by conventional sequencing had at by small sample size, potential selec- antiretrovirals and development of drug least 1 major mutation detected by the tion bias, and the limited number of resistance. Schapiro highlighted several more sensitive assay, 2% of whom had mutants that could be detected by the examples of how this genetic variability dual-class resistance. In a separate co- sensitive assay employed. before antiretroviral exposure can affect hort of patients, 7% (21 of 302) of pa- Johnson and colleagues (Abstracts 61, development of drug resistance muta- tients with known baseline resistance 639) conducted a retrospective analy- tions. Patients with subtype B who ex- gained resistance to another drug sis of antiretroviral-naive patients who perience virologic failure in the context class, based on real-time PCR testing. participated in the treatment trials CNA of nelfinavir treatment are more likely Rates of triple-class resistance doubled 30021 and 30024 and received efavi- to develop the D30N PI resistance muta- in this group to 5%. renz and lamivudine with either aba- tion than they are to develop the L90M Paredes and colleagues compared cavir or zidovudine. Of 316 patients, mutation, whereas patients with sub- the detection of M184V and D30N 95 had virologic failure (HIV-1 RNA lev- type C are more likely to develop L90M.8

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Subtypes B and C differ in consensus combination with other resistance mu- not dictate a particular antiretroviral sequence at position 89 (89L and 89M, tations (Abstracts 591, 592). In areas regimen. Resistance databases should respectively). When the D30N mutation where subtype C is prevalent, K65R is continue to be expanded to include is inserted into a virus with 89M, there found at relatively higher rates11 and is new information regarding resistance is no viral replication, whereas insertion selected more rapidly in culture by sub- mutations in a variety of subtypes and of L90M allows for a replication capacity type C than other subtypes.12 Coutsinos algorithms should be updated accord- of 78.9%. This implies that 89M strains, and colleagues (Abstract 585) evaluated ingly. Furthermore, as new antiretrovi- and therefore a majority of subtype-C vi- whether the effects of K65R mutation ral medications are developed, the po- rus strains, do not replicate successfully on reverse transcriptase in subtype C tential effect of subtype variability on with D30N mutation and as a result the differ from its effects in subtype B. The response to treatment should continue L90M mutation is found more common- authors found that subtype C recombi- to be evaluated (Abstract 624). ly than D30N among subtype C patients nant virus with the K65R mutation had in whom nelfinavir-containing treat- decreased replication capacity that is Resistance in Resource-limited Set- ment is failing.9 Subtype genetic vari- enhanced by M184V mutation and that tings. Marconi and colleagues (Ab- ability can also affect resistance through M184V resensitizes K65R to tenofo- stract 94) presented rates of resistance different codons that code for the same vir. These results are similar to what is after virologic failure among a cohort amino acid at key resistance positions. found in subtype B. of patients in Durban, South Africa. At position 106, both subtype B and C One hundred and forty-one patients consensus sequences are V106, howev- Subtype G and Resistance. In Nige- who had been on antiretroviral thera- er, at the nucleotide level, subtype B se- ria, subtype G and CRF 02-A/G are the py for at least 24 weeks, were on their quence is GTA whereas subtype C is GTG. predominant subtypes. Idigbe and col- first regimen of potent antiretrovirals, The NNRTI resistance mutation V106M leagues (Abstract 641) evaluated the or had history of prior mono- or dual- is encoded by ATG. In order for subtype prevalence of resistance mutations antiretroviral therapy, and who had B V106 (GTA) to convert to V106M (ATG) among patients in Nigeria in whom a virologic failure (defined as an HIV-1 it would require a 2-step conversion regimen of stavudine/lamivudine/ne- RNA level >1000 copies/mL, failure through GTG. In contrast, subtype C re- virapine was failing. Of 125 patients, to achieve at least a 1-log10 copies/mL quires only a 1-step conversion: GTG to a majority were subtype G (43%) or decrease in viral load after 4 weeks, or ATG. The hypothesis that the preferred CRF 02 (42%). Twenty-two (17.6%) rebound after virologic suppression) pathway of resistance in subtype C at were susceptible to all antiretrovirals, were included in this cross-sectional V106 is V106M is strengthened by the indicating likely non- or poor adher- study. Of these patients, 47.6% were observation that clinically, among pa- ence as the cause of virologic failure, on a regimen of stavudine/lamivudine tients in whom efavirenz is failing the and 7 (5.6%) had resistance only to plus either efavirenz (43.3%) or ne- V106M resistance mutation is found NNRTIs and 93 (74.4%) had resistance virapine (4.3%), and 31.2% were on more frequently in those with subtype to NNRTI with TAMs or lamivudine re- a regimen of zidovudine/lamivudine C virus (24%) than those patients with sistance. The most common resistance plus either efavirenz (21.3%) or nevi- subtype B virus (0.3%).10 mutations were M184V, Y181C, and rapine (9.9%). In 71.6%, at least 1 sig- K103N and there were no statistically nificant resistance mutation emerged Subtype C and Drug Resistance. Wal- significant differences in prevalence of (63% nRTI, 66% NNRTI, 4% PI) and lis and colleagues (Abstract 661) evalu- resistance between treatment-expe- in 53.9%, dual-class mutations were ated resistance patterns in 115 pa- rienced and treatment-naive patients present. Of patients with no prior his- tients from 2 clinics in Johannesburg, nor among subtypes. There did, how- tory of antiretroviral therapy, those on South Africa, in whom antiretroviral ever, appear to be a higher frequency a regimen of zidovudine/lamivudine/ therapy was failing, 94% of whom had of TAMs (K70R and D67N) in patients NNRTI had statistically significantly subtype C virus. They found that resis- with subtype G than in those CRF 02. higher rates of mono- and dual-class tance patterns were similar to those Patterns of resistance in subtype G vi- resistance (approximately 85% and found in patients with subtype B virus rus are similar to those described in 69%, respectively) than patients on a with the exception of higher rates of subtype B infection but there was a stavudine/lamivudine/NNRTI regimen V106M, K65R, G19A, and P225H mu- higher prevalence of TAMs in subtype (approximately 70% and 53%, respec- tations. The impact of these resistance G than in CRF 02. tively). Patients who had a history of mutations on second-line treatment is Schapiro (Abstract 59) concluded antiretroviral therapy had no statisti- unclear and the authors suggest that that although it is clear that genetic cally significant difference in presence these findings should be confirmed in variability between subtypes impacts of at least 1 resistance mutation but pa- larger controlled studies. resistance, the clinical significance of tients on a regimen of ritonavir-boosted The nRTI resistance mutation K65R this impact depends on the drug and lopinavir and 2 nRTIs had statistically is relatively rare in subtype B and the subtype. Thus far, subtype does significantly lower rates of dual-class causes decreased replication capacity not appear to influence antiretroviral resistance than patients on an NNRTI- that can be augmented or decreased in therapy success or failure and should based regimen (approximately 20% vs

70 International AIDS Society–USA Topics in HIV Medicine

80%, respectively). The most preva- stract 640), 65 of 128 plasma samples least 3 TAMs). All 10 patients with teno- lent resistance mutation was M184V from the year 2002 and 48 of 117 fovir resistance had concurrent NNRTI- (54.6%) followed by K103N (43.3%), samples from the year 2004 were suc- resistance mutations. Factors associat- with K103N and M184V mutations cessfully amplified and evaluated for ed with presence of tenofovir resistance appearing together at a rate of 33%. resistance mutations. No resistance included longer duration of antiretrovi- TAMs were present in 29% of patients mutations were identified among sam- ral therapy prior to detection of failure with resistance with the TAM 2 path- ples from 2002 and only 2 patients had (OR, 1.12; 95% CI, 1.03-1.21) and high- way representing a majority of these resistance mutations (T69D, K70R) in er level of HIV-1 RNA at time of failure mutations (17.7%). In multivariate samples obtained from 2004. Using the (OR, 10.48; 95% CI, 1.77-62.13). analysis, presence of at least 1 resis- sensitive allele-specific real-time PCR tance mutation and virologic failure assay, 1 additional sample was found Resistance to New Antiretrovirals were significantly associated with re- to contain K103N. Prevalence of TDR cent or history of opportunistic infec- was less than 5%. Although prevalence Resistance to and Daruna- tion (OR, 3.10; 95% CI, 1.27-7.58) of resistance was low, it increased from vir and Cross-resistance to PIs. Koh and history of HIV-1 RNA level below 2002 to 2004. As availability of anti- and colleagues (Abstract 606) conduct- 300,000 copies/mL at enrollment (OR, retroviral treatment increases, national ed an in vitro analysis of emergence 5.96; 95% CI, 1.08-32.8). Resistance surveys evaluating prevalence of drug of darunavir resistance, comparing was not associated with adherence resistance will be important in assess- a wild-type strain of HIV-1 with poly- but this may have been due to under- ing trends in drug resistance. clonal strains of HIV-1 obtained from 8 reporting of nonadherence, which was In a cohort of 106 patients on anti- patients with known treatment failure measured by self-report. retroviral therapy in Côte d’Ivoire (Ab- of 9 to 11 antiretrovirals. They found Chaix and colleagues (Abstract 646) stract 645), patients were followed up that it was difficult to develop daruna- presented data on a large cohort of pa- for a median of 2 months to evaluate vir resistance in the wild-type strain tients in Côte d’Ivoire who received con- the correlation between baseline char- but in the polyclonal multi-resistant tinuous antiretroviral therapy and were acteristics, including resistance, serious strains, mutants with high levels of re- followed up for 6 months as part of a morbidity (WHO stage III-IV classifica- sistance to darunavir, , am- prerandomization phase for structured tion, hospitalization, or death), and im- prenavir, , nelfinavir, ritonavir, treatment interruption. The majority of munologic failure (CD4+ count below and lopinavir emerged. The authors patients were women (76%) and initi- 200 cells/µL). At baseline, 54% were on suggested that there is a significant ated a regimen of zidovudine/lamivu- 2 nRTIs and a PI, 44% were on 2 nRTIs barrier to development of darunavir dine/efavirenz (90%) At 6-month follow and an NNRTI, 58% had detectable viral resistance; however, in the setting of up, 10 patients had died, 1 was lost loads (HIV-1 RNA level above 300 cop- multi-resistant virus, high levels of re- to follow up, and 15 had no viral load ies/mL), 20% had detectable viral loads sistance to darunavir can emerge. data available. One hundred seventeen without major resistance mutations, and In Abstract 607, investigators as- patients (15%) had detectable HIV-1 22% had detectable viral loads with at sessed darunavir cross-resistance to RNA levels (above 300 copies/mL) of least 1 major resistance mutation. The ritonavir-boosted , tiprana- which samples from 112 were success- most common mutations were M184V, vir, and lopinavir by evaluating resis- fully amplified. Rates of resistance were D67N, M41L, K103N, and L90M. De- tance profiles of 2682 patients with at 4.2% overall, 3.9% in patients on an tectable viral load with or without evi- least 1 major PI mutation. There was NNRTI-based regimen, and 6.9% in pa- dence of resistance was not predictive minimal evidence of cross-resistance tients on a PI-based regimen. Women of serious morbidity, but presence of between darunavir and atazanavir or who received zidovudine/nevirapine at least 1 resistance mutation was as- tipranavir. There was more of a corre- for PMTCT had high rates of resistance sociated with immunologic failure (HR, lation of darunavir resistance with lopi- (20.4%) compared with women who 4.32; 95% CI, 1.38-13.57). navir resistance, and the tightest corre- received zidovudine/lamivudine/nevi- Sungkanuparph and colleagues (Ab- lation was with amprenavir resistance. rapine (0%) or zidovudine alone (0%) stract 663) evaluated rates and predic- Patient-derived viral strains susceptible for PMTCT. This cohort demonstrated tors of tenofovir resistance among teno- to darunavir were also susceptible to a high rate of virologic success (85%) fovir-naive patients in whom a first-line amprenavir, tipranavir, and lopinavir at at 6 months, with low rates of virologic regimen of stavudine/lamivudine/nevi- rates of 100%, 89%, and 99.7%, re- resistance (4.2%). However, the preva- rapine was failing. Ninety-eight patients spectively. Among patient strains with lence of low-frequency variants among met inclusion criteria, which included amprenavir resistance, 89% retained patients in whom treament failed but history of undetectable viral load at 4 to at least partial susceptibility to daruna- who did not have detectable resistance 6 months after antiretroviral initiation vir (39% remained completely suscep- (70%) was not assessed. and at least 2 subsequent HIV-1 RNA tible to darunavir). In 84% and 88% In a cross-sectional analysis of HIV- levels of above 1000 copies/mL. Ten of strains with tipranavir and lopina- 1-infected pregnant women in the patients were noted to have tenofovir vir resistance, respectively, at least Gauteng Provence of South Africa (Ab- resistance (6 with K65R and 4 with at partial susceptibility to darunavir was

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retained. Similarly, in Abstract 609, assist in optimizing the use of these commonly occurring integrase-inhibi- investigators found that patients with agents in PI-experienced patients. tor-associated resistance mutations known virologic failure in the setting of were V72I (17% of subtype B, 19% amprenavir or evidence of amprenavir Resistance to Integrase Inhibitors. A non-subtype B), V201I (11% subtype B, resistance retained good virologic re- series of in vitro studies were conducted 17% non-subtype B), V165I (11% sub- sponse to darunavir at 48 weeks. Both with the investigational strand-trans- type B, 9% non-subtype B), and T206S studies found a correlation between fer inhibitor elvitegravir to characterize (9% subtype B, 47% non-subtype B). genotypic evidence of resistance to da- resistance mutations to this integrase The clinical significance of naturally runavir and amprenavir, but this cross- inhibitor (Abstract 627). Two major occurring resistance to integrase inhibi- resistance appeared to be overcome patterns of resistance to elvitegravir tors is an area of ongoing research. by the high potency of darunavir at the emerged: T66I and E92Q. T66I de- lower levels of amprenavir resistance. creased sensitivity to elvitegravir 15-fold Resistance to Entry Inhibitors. Base- Furthermore, there did not appear to but had no effect on susceptibility to line susceptibility to CCR5 blockers be easily definable cross-resistance of raltegravir. E92Q decreased susceptibili- as HIV-1 entry inhibitors depends on darunavir to other PIs. ty to both elvitegravir (30-fold) and ralte- the presence of a predominant CCR5- Elston and colleagues (Abstract 602) gravir (6-fold). Minor mutations includ- tropic virus population in an individu- evaluated development of cross-PI ing F121Y and S147G were identified to al, and change in tropism may be one resistance in 62 patients who experi- have low-level resistance to elvitegravir avenue for HIV-1 to escape from CCR5 enced virologic rebound while on a tip- and augment resistance conferred by blockade. Tropism was initially thought ranavir-based regimen. A majority of T66I and E92Q. All 4 of these resistance to be the major source of resistance failures were associated with the V82L/T mutations have been observed to cause to entry inhibitors. However, the ma- mutation (47%) and 43% had other resistance to other integrase inhibitors jor mechanism of resistance to CCR5 tipranavir resistance mutational pat- and have no effect on susceptibility to blockers, such as maraviroc, appears terns, typically L33F and 154V/A; 10% other classes of antiretrovirals including to result from mutations that permit had no identified genotypic changes. nRTIs, NNRTIs, and PIs. HIV-1 to utilize the CCR5 coreceptor Virus in 84% of all patients remained Several studies evaluated the natu- despite the presence of bound inhibi- fully susceptible to darunavir and no ral occurrence of integrase-inhibitor tor (Abstract 108). The following 2 ab- patient had complete darunavir resis- resistance in antiretroviral-naive and stracts conducted clinical and in vitro tance. Virus remained susceptible to all treatment-experienced individuals. In- studies to evaluate factors associated other PIs with the possible exception tegrase sequences from 2081 patients with tropism switch in HIV-1 strains. of atazanavir. Patients with non-V82L/T (1744 of whom were treatment-naive) The rate and predictors of tropism tipranavir resistance mutations had in- from the GenBank database were evalu- switch among chronically infected pa- creased susceptibility to all other PIs. ated (Abstract 623) and included strains tients with known antiretroviral drug re- Investigators from Tipranavir ANRS that were representative of a variety of sistance was evaluated among patients (Agence Nationale de Recherches sur subtypes including subtype C (n=504), in the Study on the Consequences of le SIDA) study group (Abstract 612) subtype A (n=288), and subtype B the Protease Inhibitor Era (SCOPE) co- identified mutations associated with (n=274). Of 288 amino acid positions, hort (Abstract 619). Sixty-six patients loss of virologic response among PI- 162 were polymorphic, all of which were met inclusion criteria, which included experienced patients on tipranavir- in the non-catalytic region of integrase. baseline plasma HIV-1 RNA level above based regimens (n=143). A tipranavir There were low rates of conservative 1000 copies/mL, presence of at least 1 mutation score was developed based polymorphisms at extended active resi- major or 1 minor genotypic resistance on virologic data from a multi-PI-ex- dues 141, 151, 155 and 156. Similarly, mutation, and use of stable antiretro- perienced cohort and included amino researchers from the Aaron Diamond viral regimen for 120 days or more acid positions 36 to 53, as well as 58, AIDS Research Center (Abstract 625) before baseline. Patients were followed 69, and 89. In a multivariate analysis, found few polymorphisms associated up until regimen change. At baseline, previous enfuvirtide use (OR, 3.99; P with integrase-inhibitor resistance in vi- 52, 22, and 2 patients had CCR5-, dual = .0015) and a high tipranavir muta- tro among 13 patients with multi-drug and mixed-, and CXCR4-tropic virus, tion score, implying higher numbers of resistance virus and 103 recently infect- respectively. Risk of progression from tipranavir-associated resistance muta- ed, antiretroviral-naive patients. Yerly CCR5 to dual and mixed tropism at 1 tions, (OR, 6.8; P < .001) were asso- and colleagues (Abstract 626) evaluated year was 12% (95% CI, 6-26%) and ciated with poorer virologic response, prevalence of integrase polymorphisms in multivariate analysis, presence of and an efavirenz background regimen in 35 patients with subtype B and 54 CCR5 Δ32 heterozygosity was inde- (OR, 0.14; P = .035) was associated patients with non-subtype B virus and pendently predictive of switch (P = with better virologic response. Under- found that polymorphisms associated .024). Risk of switch from mixed and standing the susceptibility and resis- with integrase-inhibitor resistance were dual to pure CXCR4 and to CCR5 was tance patterns that emerge with tip- present at similar levels in subtype B 8% (95% CI, 1-43%) and 11% (95% ranavir and darunavir treatment will and non-subtype B isolates. The most CI, 3-37%), respectively. Neither of the

72 International AIDS Society–USA Topics in HIV Medicine

2 CXCR4-tropic viruses identified at curs through facilitated excision of the K65R, K65R/A62V, K65R/S68G, and baseline had observed tropism switch. nRTI. These mechanisms of resistance K65R/A62V/S68G mutants, and their Of populations noted to have a tropism appear to be antagonistic; there is fitnesses were compared with wild- switch, 30% showed small changes in evidence that when M184V, L74V, or type virus in the presence and absence CXCR4 at entry as measured by reduc- K70E occur in conjunction with TAMs, of tenofovir. The results suggested that tions in relative light units, implying the virus or enzyme is less susceptible A62V and S68G act as partial compen- that the clinical significance of switch to zidovudine. K65R and TAMs (of the satory mutations for K65R by increas- in these populations may be limited. TAM 67 pathway) appear to have bidi- ing replication capacity. In the absence This study implies that deferring a rectional antagonism: clinical isolates of tenofovir, wild-type virus was more change in antiretroviral treatment with both mutations are infrequently fit than the K65R/A62V/S68G mutant, among patients with known resistance observed. The presence of K65R with but in the presence of greater than may carry a small risk of losing CCR5 TAM 67 decreases the resistance to zid- 7µM of tenofovir, the triple mutant tropism (approximately 10%). ovudine in the presence TAM 67 alone was more fit. Incorporation kinetics Moncunill and colleagues (Abstract from 54-fold to 1.5-fold, and TAM 67 showed that the K65R mutants with 618) conducted in vitro studies of CCR5 with K65R decreases the resistance A62V/S68G exhibited more efficient coreceptor switches in the presence to tenofovir in the presence of K65R incorporation of dATP and dGTP than and absence of CCR5, CXCR4, and alone from 4.2-fold to 2.4-fold. mutants with K65R alone. reverse transcriptase inhibitors (RTIs). Sluis-Cremer also provided evidence In contrast to A62V and S68G, the They found that in the absence of drug that antagonism among resistance K70E mutation, which is associated pressure, 3 of 6 strains switched from mutations affects virologic response. with patients in whom tenofovir-con- CCR5 to CXCR4 and demonstrated In the ESS30009 study13, at 12 weeks taining regimens are failing, is rarely increased rates of replication. In the 49% (50 of 102) of patients random- found in conjunction with K65R (Ab- presence of CCR5 antagonists, CXCR4- ized to tenofovir/abacavir/lamivudine stract 584). Site-directed mutagen- using virus emerged more quickly in were virologic nonresponders. Of these esis has shown very poor replication the presence of TAK-799 but was pre- virologic nonresponders, 98% had capacity among K70E/K65R double vented by plerixafor (AMD3100). These M184V/I, either in combination with mutants, suggesting antagonism be- studies indicate that cell culture mod- (44%) or without (53.5%) K65R. This tween these mutations.16 Using molec- els can be useful in predicting the pro- relatively high rate of virologic nonre- ular dynamic simulations, Kagan and pensity of clinical isolates to develop sponse could be the result of a low ge- colleagues (Abstract 592) evaluated resistance in the setting netic barrier to emergence of M184V whether there was a structural basis to of antiretroviral drug pressure. and K65R and the fact that K65R con- this antagonism. In wild-type virus, the fers resistance to all of the medications K65 was found to stabilize the triphos- 14 Antiretroviral Resistance Mutations: in the regimen. This is in contrast to phate moiety of the dNTP ligand but 15 Interactions and Effects on Fitness the A5095 study in which patients with K65R mutation the stabilization randomized to receive zidovudine/aba- was lost. The K70 in wild type appears Resistance to Nucleoside Reverse cavir/lamivudine had a rate of virologic to compensate for the loss of stabili- Transcriptase Inhibitors. Sluis-Cremer nonresponse of only 21% (82 of 382). zation conferred by the K65R mutant. presented an overview of mechanisms Of these nonresponders, 70% had evi- The double mutant K65R+K70E has of resistance to nRTIs and interactions dence of resistance: 51% (29 of 57) no compensation for this loss of stabi- among RTI resistance mutations (Ab- with M184V alone, 14% (8 of 57) with lization, which leads to a more severe stract 58). HIV-1 reverse transcriptase TAMs and M184V in combination, and defect, thus providing a structural basis is essential for transcribing an RNA 3.5% (2 of 57) with TAMs alone. Sluis- for the antagonism between the K65R template into DNA. The nRTIs are nu- Cremer hypothesized that the relative- and K70E mutants. Molecular dynam- cleoside or nucleotide analogues that ly low rate of virologic nonresponse ic simulation may be a useful tool to compete with the naturally occurring could be attributed to the higher ge- evaluate other antagonistic mutation deoxynucleotide triphosphate (dNTP) netic barrier to TAMs and M184V, as interactions. and cause chain termination that pre- well as the antagonism between TAMs vents formation of HIV DNA. Previous and M184V. Resistance to Enfuvirtide. Enfuvirtide studies have shown that resistance to blocks fusion of HIV with CD4 through nRTI occurs due to preferential incor- K65R. The K65R mutation is associated competitive interactions with the HR1 poration dNTP over the nRTI (a process with decreased susceptibility to nRTIs and HR2 helices of the trans- known as discrimination) or increased and decreased replication capacity. In a membrane protein. Genotypic changes excision of the nRTI. Kinetic data have database analysis of patients in whom in HR1 and HR2 have been associated shown that with the K65R, K70E, L74V, tenofovir therapy failed (Abstract 591), with resistance to enfuvirtide. Resis- M184V, and Q151M mutations, resis- K65R was often accompanied by A62V tance mutations in the HR1 (N43D) tance occurs through discrimination, and S68G mutations. Site-directed and HR2 (E137K) sequences among 5 whereas TAM-mediated resistance oc- mutagenesis was conducted to create enfuvirtide-experienced patients were

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identified, cloned, and evaluated for vir-, indinavir-, nelfinavir-, or ampre- Y115F, and K65R had completely dis- their effect on fitness and response navir-associated mutations containing appeared within 4 months of treatment to enfuvirtide through in vitro assays the insert had increased fitness. In interruption and were associated with of viral envelope fusogenicity and in- this study, presence of TTNTRNS in- the fastest viral load increase, which fectivity (Abstract 620). N43D single sert near the p17/p24 cleavage sites is consistent with their detrimental mutants and N43D/137K double mu- improved the fitness of otherwise effects on fitness. In contrast, TAMs, tants had decreased susceptibility to replication-compromised PI-resistant L74V, E44D, and H208Y progressively enfuvirtide compared with wild type at mutants. declined during treatment interrup- magnitudes of 28-fold and 32-fold, re- Hypersusceptibility to Non-nucleo- tion but were still present in more than spectively. However, the N43D single side Reverse Transcriptase Inhibitors. 10% of individuals 9 months post- mutant had decreased fitness com- The nRTI induction of NNRTI hyper- treatment interruption. E44D, V181I, pared with wild type by 92%, and the susceptibility and accompanying influ- E203K, and H208Y were all associated N43D/E137K double mutants had no ences on virologic response have been with maintenance of TAM 1 pathway statistically significant difference in previously described but the mecha- mutations and K20R and D218E were fitness compared with wild type. The nism of this mutational interaction has associated with persistence of TAM 2 E137K single mutant conferred no remained unclear. Clark and colleagues pathway mutations. The dynamics of statistically significant difference in (Abstract 598) evaluated 3 nRTI muta- resistance mutation evolution in the sensitivity to enfuvirtide or in fitness tions (118I, 208Y, and 215Y) that are absence of drug pressure appears to be compared with wild type. The N43D strongly associated with NNRTI hyper- related to the relative fitness of the vi- mutation appeared to decrease sus- susceptibility and their effects in vitro rus conferred by resistance mutations ceptibility to enfuvirtide, but at a sub- on fitness and reverse transcriptase and resistance mutation combinations. stantial cost to fitness, for which the activity. Replication capacity varied Prevalence of low-frequency resistance E137K mutation can compensate. An depending on the combination of mu- variants, however, was not assessed. analysis of previously published data tations present: 208Y/215Y, 118I/208Y/ Charpentier and colleagues (Ab- regarding prevalence of resistance 215Y, and 118I/215Y mutants had rep- stract 622) evaluated the disappear- mutations to enfuvirtide supported lication capacities of 40%, 35%, and ance of mutations associated with re- this hypothesis: the N43D mutation equal to wild type, respectively. The sistance to enfuvirtide after treatment occurred at higher rates among pa- effect of mutation combination on re- discontinuation. Bulk sequencing was tients with E137K/Q mutations than verse transcriptase activity and poly- used to detect resistance mutations in those without E137K/Q mutations. merase activity of reverse transcriptase 7 patients who had immunovirologic was similar to its effect on replication failure while on enfuvirtide at baseline, Resistance to Protease Inhibitors. capacity: 208Y/215Y, 118I/208Y/215Y, during treatment, and after treatment. Previous studies have shown that ami- and 118I/215Y exhibited 47%, 30%, Molecular cloning was used to detect no acid inserts near the cleavage and and equal to reverse transcriptase ac- low-frequency resistance variants. Me- noncleavage sites in Gag compensate tivity compared with wild type, respec- dian duration was 6 to 4 for decreased viral fitness secondary tively. It was hypothesized that hyper- months. Of 7 patients, 3 had complete to PI-resistance associated mutations. susceptibility to NNRTIs conferred by reversion to wild type, 2 had persis- Aoki and colleagues (Abstract 601) 208Y/215Y and 118I/208Y/215Y mu- tence of enfurvirtide-resistant virus evaluated the effect of a 7 amino acid tants may be related to altered gag- as a minority population, and 2 had insert (TTNTRNS) near the p17/p24 pol processing and the mechanism persistence of resistance as a major- cleavage site in a heavily drug-experi- of hypersusceptibility conferred by ity population. A high proportion of enced, HIV-infected patient. Samples 118I/215Y double mutants is distinct patients in whom resistance persisted were obtained throughout the course and remains to be determined. were those who received enfurvirtide of treatment that included a regimen for long periods of time (>6 months). of zidovudine/lamivudine/nelfinavir Fading of Resistance Mutations with There was no association between en- followed by stavudine/ritonavir-boost- Treatment Interruption. Ceccherini- furvirtide resistance mutations and the ed saquinavir and then stavudine/rito- Silberstein and colleagues (Abstract kinetics of mutation disappearance. navir-boosted saquinavir/abacavir. 587) evaluated the evolution of resis- Further investigation is required to de- Seventy percent of clones from the tance mutations among 138 patients termine the clinical significance of per- patient contained the TTNTRNS insert experiencing virologic failure who un- sistent enfurvirtide resistance. and were found early in the course derwent treatment interruption for at of antiretroviral treatment. The pres- least 1 month. Genotypes were avail- Mutations in the Connection and ence of the insert had no effect on the able at the time of virologic failure and RNase H Domains of Reverse propensity to acquire nelfinavir mu- at least once during treatment inter- Transcriptase tations. Introduction of the insert to ruption. Disappearance of resistance wild-type virus resulted in decreased mutations correlated with known ef- The HIV-1 reverse transcriptase is com- fitness. However, clones with saquina- fects of resistance on fitness. M184V, posed of 3 domains of the p66 subunit

74 International AIDS Society–USA Topics in HIV Medicine

(polymerase, connection, and RNase NNRTIs and nRTIs. Hachiya and col- over time. The following section is a H) and 2 domains of the p51 subunit leagues (Abstract 593) identified 2 clin- selected review of predictors of clinical (polymerase and connection). Most ical isolates that were phenotypically outcomes from cohort studies at this resistance assays sequence only the highly resistant to nevirapine and dela- year’s conference. polymerase domain and do not evalu- virdine despite a lack of NNRTI-asso- Sabin and colleagues (Abstract 528) ate for resistance mutations in the con- ciated resistance mutations. Sequenc- presented an analysis from the Collab- nection and RNase H domains. Sev- ing of the entire reverse transcriptase oration of Observational HIV Epidemi- eral studies at this year’s conference domain of these isolates identified ological Research in Europe (COHERE), presented evidence that mutations in the N348I. Compared with wild type, a collaboration of 33 cohorts from 30 these infrequently analyzed domains N348I mutants conferred increased European countries contributing data may be clinically significant. resistance to zidovudine (8.6-fold), di- on 827 children under 17 years of age danosine (5-fold), nevirapine (22-fold), and 49,094 adults. Patients eligible Mutations in the RNase H Domain. and (4.3-fold). for inclusion in this study (n=49,921) The function of RNase H is to cleave Yap and colleagues (Abstract 594) were antiretroviral therapy naive, aged the RNA moiety of RNA and DNA hy- performed genotyping on 1377 treat- 6 years or older, had initiated antiretro- brids during reverse transcription. Re- ment-naive and treatment-experienced viral therapy between 1998 and 2006, cent studies have shown that HIV-1 patients and identified N348I as the and had more than 1 CD4+ cell count reverse transcriptase mutations in the ninth most prevalent mutation, oc- and plasma HIV-1 RNA measurement RNase H domain can increase nRTI curing 11.3-times more frequently in taken pre-antiretroviral initiation and resistance, presumably by decreasing treatment-experienced patients than during follow up. Baseline characteris- RNase H activity, allowing more time in treatment-naive patients. N348I tics included median age of 37 years, for excision of the incorporated nRTI- appeared relatively early in virologic 29% female, CD4+ count of 210 cells/ monophosphate.17 failure, before the appearance of TAMs μL, and plasma HIV-1 RNA level of 4.9

To evaluate mutations in reverse and about the same time as NNRTI-re- log10 copies/mL. Thirty-eight percent transcriptase outside of the catalytic sistance mutations, and was associated had initiated an NNRTI-based regimen domain, selections of zidovudine-re- with zidovudine and combination zid- and 28% had initiated non-ritonavir- sistant HIV-1 were made in vivo and ovudine/nevirapine treatment. N348I boosted PI regimens. the entire coding region of reverse decreased susceptibility to zidovudine Age was found to be a predictor of transcriptase was sequenced (Abstract between 2-fold alone and 4-fold in immunologic, virologic, and clinical 90). Sequencing identified the A371V combination with TAMs, did not an- outcome. Immunologic responses to mutation (located in the connection tagonize M184V resistance to zidovu- therapy in the cohort were appropri- domain) and Q509L mutation (lo- dine, conferred resistance to efavirenz ate, with 59.2% achieving a confirmed cated in the RNase H domain). Using and nevirapine as a single mutant, and CD4+ cell response by 1 year, but site-directed mutagenesis, A371V and augmented K103N-related resistance the probability of an immunologic re- Q509L mutants were found to be 1.7- to efavirenz and nevirapine. Molecular sponse was higher in younger individ- times more resistant to zidovudine dynamics simulation suggested that uals (particularly those under 12 years than wild type, but in conjunction with the N348I mutation inhibits movement of age) and reduced in those over 60 TAMs (D67N and K70R), resistance of the thumb region of the polymerase years of age. In the first year of ther- increased to 39-fold that of wild type domain, thereby allowing more time apy, 53.7% of patients achieved a vi- (compared with a 4.6-fold increase for zidovudine excision. These stud- rologic response to antiretroviral treat- with TAMs alone). The mechanism of ies indicate that this novel N348I has ment, but the probability of response augmented resistance by A371V and clinical relevance and suggest that ge- was lower in those aged 6 to 17 years, Q509L appeared to be a decrease in notypic and phenotypic analysis of the and higher in those aged 50 years and RNase H cleavage activity, which may entire reverse transcriptase should be older than those aged 30 to 39 years. lead to facilitated zidovudine excision conducted to identify the prevalence Older individuals were more likely in the presence of TAMs. RNase H is of other clinically-significant resistance to develop an AIDS-defining event or also being evaluated as a novel target mutations outside of the polymerase death in the first year on antiretrovi- for antiretroviral therapy (Abstract 89), domain. rals, with adjusted HRs of 1.19 (95% further emphasizing the need to evalu- CI, 1.05-1.34) and 1.34 (95% CI, 1.19- ate the effects of RNase H activity on Predictors of Immunologic, 1.51) for those aged 55 to 59 years and resistance and fitness. Virologic, and Clinical Outcomes over 60 years. Braithwaite and colleagues (Ab- Mutations in the Connection Do- stract 520) examined the relationship main: N348I. Abstracts 593 and 594 From the first days of the Multicenter between antiretroviral regimen, ad- described the resistance mutation AIDS Cohort Study (MACS), investiga- herence, and virologic response in a N348I, which is found in the connec- tors have gained insights by following cohort of 6394 patients initiating an- tion domain and confers resistance to up groups of HIV-infected individuals tiretroviral therapy within the Veterans

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Affairs Healthcare System. Initiation rologic failure between patients who Clinical Outcomes Associated with of treatment with NNRTI-based regi- reported perfect adherence and those Resistance mens was compared with initiation of who reported missing 1 dose. HRs ritonavir-boosted PI-based regimens. for 2 missed doses and more than Phillips and colleagues (Abstract 532) Adherence, estimated from pharmacy 2 missed doses were 1.89 (95% CI, presented data from the UK Collabora- refill data, was statistically significantly 1.24-2.88) and 3.88 (95% CI, 2.74- tive HIV Cohort Study (UK CHIC) on greater with efavirenz-based regimens 5.48), respectively. In a multivariate the cumulative risk of extensive triple- (67%) and nevirapine- based regimens analysis, nonadherence, defined as a class failure. They defined failure of a (65%) than with boosted (59%) or un- self-report of missing 2 or more doses drug as plasma HIV-1 RNA above 2.6 boosted (61%) PI-based regimens (P < of medication in the previous 28 days, log10 copies/mL after more than 4 .001). In multivariate analyses, plasma was associated with an increased risk months of continuous use of that drug. HIV-1 RNA suppression was inferior in of virologic rebound (HR, 2.82; 95% Extensive failure of the nRTI class was nevirapine-based regimens (OR, 0.60), CI, 1.76-4.50). Other risk factors for failure of at least 1 drug from each of boosted PI- (OR, 0.57), and unboosted virologic rebound were having had the following sub-classes: zidovudine PI-based regimens (OR 0.48) com- more than 5 previous antiretroviral and stavudine; lamivudine and emtric- pared with efavirenz (all, P < .001). regimens (HR, 2.75; 95% CI, 1.65- itabine; and didanosine, tenofovir, and Using data from the Swiss HIV Co- 4.61) and comedication for cardio- abacavir. Extensive failure of NNRTIs hort Study, predictors for long-term vascular problems, opportunistic in- was determined by failure of either CD4+ count increases in 2860 pa- fections, or hepatitis C virus infection nevirapine or efavirenz, and extensive tients initiating first-line antiretroviral (HR, 2.42; 95% CI, 1.54-3.82). failure of PIs involved virologic failure therapy were evaluated (Abstract 518). Gibb and colleagues (Abstract 701) of at least 1 ritonavir-boosted PI. Ex- Sixty-three percent achieved virologic combined data from 11 studies of HIV- tensive triple-class failure was defined suppression, and median CD4+ count 1-infected children in resource-limited as failure of all 3 classes. Of 10,603 increases were 87, 52, and 19 cells/μL settings to examine factors predicting patients evaluated, 25% were female, in the 3 time periods examined: 1, 2 to mortality for these children. Ten Afri- and median age, CD4+ count, and 3, and 4 to 5 years after plasma HIV- can studies and 1 Brazilian study of un- viral load were 36 years, 185 cells/μL,

1 RNA suppression, respectively. In treated children older than 12 months and 4.96 log10 copies/mL, respectively. multivariate modeling, median CD4+ were used to form a retrospective co- During 38,190 person-years of obser- count increase was statistically signifi- hort of 2510 children, 3769 person- vation, 169 patients developed exten- cantly higher for patients with female years of observation, and 357 deaths. sive triple-class failure, 70% of whom sex (P < .001), lower age (P < .001), The majority (81%) of the follow up had at least 1 prior measurement of higher plasma HIV-1 RNA at start of occurred after the initiation of co-tri- plasma HIV-1 RNA below 1.7 log10 cop- antiretroviral therapy (P = .002), and moxazole therapy. The first available ies/mL. Of 169 patients, 95 (56%) sub- CD4+ count of below 650 cells/μL at data points were used as baselines, sequently had at least 1 plasma HIV-1 start of the period (P = .010). and the investigators found a median RNA measurement below 1.7 log10 Another evaluation of the Swiss HIV age of 4.0 years, CD4+ cell percent- copies/mL. A baseline CD4+ count Cohort Study determined the predic- age of 15, and weight-for-age z-score of below 200 cells/μL carried a HR of tive value of longitudinal self-reported of –1.9. Predictors of mortality were 2.2 for extensive triple-class failure (P adherence assessment for virologic re- CD4+ cell percentage, CD4+ count, < .0001), and for those with a base- bound, defined as 2 consecutive plas- weight-for-age, and hemoglobin level. line CD4+ count above 200 cells/μL, ma HIV-1 RNA measurements above Children with weight-for-age z- scores the cumulative risk of extensive triple-

2.7 log10 copies/mL (Abstract 523). lower than –3 and hemoglobin level class failure was 4% (95% CI, 2-6). Patients were included in the analysis of below 8 mg/dL had a mortality rate The correlation between resistance if they were on antiretroviral therapy, of 55.2 per 100 person-years com- and clinical outcomes was analyzed over 16 years of age, had plasma HIV-1 pared with 1.4 per 100 person-years among 1929 antiretroviral-naive pa-

RNA below 1.7 log10 copies/mL over the when weight-for-age z-score was 1 or tients in the Swiss HIV Cohort Study previous 3 months, and had completed higher and hemoglobin level was 10 who initiated treatment with at least 2 adherence questionnaires before June mg/dL or higher. This trend was seen nRTIs plus an NNRTI or ritonavir-boost- 1, 2006. Among the 2638 subjects even in children who had a baseline ed PI (n=518) from January 1999 to who met inclusion criteria, the me- CD4+ cell percentage of more than December 2005 (Abstract 667). Six- dian follow up was 2.5 years. Patients 15. This report highlights the need for ty-nine of 805 (8.6%) patients in the reported missing 1 or more doses at consideration of weight-for-age and NNRTI group and 24 of 518 (4.6%) in 25% of visits, and missing more than hemoglobin level in decisions regard- the PI/ritonavir group experienced vi- 2 doses at 9.9% of visits. A total of 97 ing antiretroviral therapy initiation in rologic failure, which was defined as patients (3.7%) experienced virologic resource-limited settings, as is recom- viral load of 500 copies/mL or higher rebound. In an unadjusted analysis, mended in the most recent WHO an- after at least 180 days on continuous there was no difference in rates of vi- tiretroviral treatment guidelines. treatment. Although discontinuation of

76 International AIDS Society–USA Topics in HIV Medicine

antiretroviral therapy due to virologic that a majority of resistance mutations apy. Data from 161 Bw4+ adult, white failure was not statistically significantly among patients with triple-class failure men initiating antiretroviral treatment different between the groups, discon- accumulated during suboptimal treat- between 1997 and 2002 were ana- tinuation due to an adverse event was ment in the 1990s and that perhaps lyzed. In the Australian cohort, baseline more common among patients on an T215Y is a marker of earlier develop- mean age of Bw4+ individuals was 4 NNRTI than among patients on PI/rito- ment of immunodeficiency. With the years older than Bw4– individuals, and navir (n=189 vs n=122, respectively, availability of newer drug classes, it re- in the Swiss cohort, mean CD4+ count log rank P = .0241). Among patients mains to be seen if multi-class failure of Bw4+ individuals was 90 cells/μL for whom genotypic resistance testing to RTIs and PIs will remain associated lower than Bw4– individuals. Baseline was available (n=1323), patients on a with mortality. plasma HIV-1 RNA, follow-up time, ini- PI/ritonavir regimen had higher rates The relationship between mortality tial antiretroviral regimen, and mode of susceptibility to lamivudine/emtric- and use of resistance testing was ana- of infection did not differ significantly itabine (75% vs 42.1%, P = .026) and lyzed using data from the HIV Outpa- between Bw4+ and Bw4– individuals to a third antiretroviral drug (90% vs tient Study (HOPS) (Abstract 660). Of in either cohort. CD4+ percentage and 52.6%, P < .001) than patients on an patients enrolled in the cohort since absolute CD4+ counts were consis- NNRTI-based regimen. There was no January 1999, 3202 were evaluated tently lower in Bw4+ carriers than in statistically significant difference in and had median follow up of 3.3 years. the remainder of the cohort from 1 to 5 susceptibility to nRTIs. Although rates Resistance testing was performed in years on antiretrovirals. CD4+ counts of virologic failure were not different 1110 of these patients. Patients who were approximately 85 cells/μL lower between PI/ritonavir-based regimens were white, had private insurance, had in Bw4+ than Bw4– individuals in the and NNRTI-based regimens, rates of a lower CD4+ count, and whose risk Swiss cohort and 55 cells/μL lower in adverse events and resistance were behavior was MSM were more likely to the Australian cohort (P = .005 and higher among patients initiated on an have had resistance testing performed. P = .01, respectively). These differ- NNRTI-based regimen. Among patients who had received po- ences were more profound in patients Predictors of mortality were evalu- tent antiretroviral therapy (n=2107), carrying the variant Bw4-80T, and re- ated among patients enrolled the Dan- receiving a resistance test and pri- mained statistically significant after ish HIV Cohort study who experienced vate health insurance were associated adjusting for virologic response rates. triple-class virologic failure from 1995 with decreased mortality even after Rosignoli and colleagues (Abstract to 2004. Triple-class failure was defined adjusting for stage of HIV disease, de- 451) presented data on the effect of as viral load above 1000 copies/mL for mographics, age, and year (HR, 0.60 antiretroviral therapy on expression of a total of 120 days while on antiretro- and 0.63, respectively). Among pa- CD279, also known as programmed viral treatment, and median time of tients who were antiretroviral naive death 1 (PD-1), and its ligand (PD-L1), follow up after triple-class failure was with CD4+ counts below 200 cells/µL which has been implicated in promot- 4.3 years. One hundred and seventy (n=257), resistance testing before ini- ing and regulating anergy of HIV-1-spe- patients experienced triple-class fail- tiation of antiretroviral therapy was also cific CD8+ cells. They examined PD-1 ure, 133 of whom received resistance protective (HR, 0.22, although 95% CI and PD-L1 activity in 22 HIV-1-infected testing. The median number of resis- approaches 1.0). Although limited by individuals on antiretroviral therapy tance mutations was 8 and 61% (81 of the retrospective nature of the study who had plasma HIV-1 RNA below 1.7

133) had resistance to 3 major classes. design, this analysis provides evidence log10 copies/mL and a median CD4+ Mortality from time of triple-class fail- that antiretroviral therapy guided by count of 547 cells/μL, and compared ure was 70 (95% CI, 54-92) per 1000 resistance testing is associated with a it with levels in 10 uninfected con- person-years in patients who expe- substantial clinical benefit. trols. There were no statistically sig- rienced triple-class failure compared nificant differences in levels of PD-1, with 29 (95% CI, 26-32) per 1000 per- Host-factor Influence on Response to even after stratification by antiretrovi- son-years from time of antiretroviral Therapy ral treatment regimen. Previous stud- initiation in all patients in the cohort. ies have shown higher levels of PD-1 In multivariate analysis, mortality rate The human leukocyte antigen (HLA) in untreated viremic patients, so this ratio (MRR) was associated with pres- variants Bw4 and Bw6 help determine may represent a normalization of PD-1 ence of 9 or more resistance mutations HLA interactions with natural killer levels with antiretroviral therapy. The (MRR, 2.3; 95% CI, 1.1-4.8), presence cells, and Bw4 has been associated mean fluorescence intensity of PD-L1 of T215Y (MRR, 3.4; 95% CI, 1.6-6.66), with enhanced control of HIV infec- on T cells was higher in HIV-1-infected G190A/S (MRR, 3.2; 95% CI, 1.6-6.6), tion. Rauch and colleagues (Abstract individuals regardless of their antiret- or V82F/A/T/S (MRR, 2.5; 95% CI, 1.2- 141) combined data from the Swiss roviral therapy status. Evidence of PD- 5.3). After adjusting for latest CD4+ HIV Cohort Study and the Western Aus- 1 activity could be a signature of the count, only presence of T215Y and lat- tralia HIV Cohort Study to examine the persistent anergic state. est CD4+ count remained associated effects of Bw4 on immunologic and vi- Liptrott and colleagues (Abstract with mortality. The authors concluded rologic responses to antiretroviral ther- 452) also explored the relationship

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between PD-1 and response to anti- mechanism of this interaction and the Interactions Between Antiretroviral retroviral treatment, but they focused clinical significance are not clear. and Non-antiretroviral Medications on PD-1.3, an allele of the PD-1 gene Kakuda and colleagues (Abstract 560) that has been shown to alter the regu- presented data from TMC125-C223, a Hoody and colleagues (Abstract 564) lation of PD-1 gene expression. PD- phase II study of (an investiga- presented data on the interaction of 1.3 genotyping and an assay for CCR5 tional NNRTI) in treatment-experienced lopinavir/ritonavir and rosuvastatin, an Δ32 were conducted on samples from subjects. The pharmacokinetic param- HMG Co-A reductase inhibitor. A drug- 77 antiretroviral-naive patients initiat- eters of etravirine were decreased by drug interaction was not expected ing efavirenz-based regimens. Median coadministration of either a PI or teno- as rosuvastatin is not a substrate for CD4+ count at baseline was 202 cells/ fovir. Etravirine trough concentrations, CYP3A4. However, investigators found μL and median plasma HIV-1 RNA AUC, and de novo enfuvirtide use were that rosuvastatin AUC was increased 2.1 fold and maximum concentration level was 4.9 log10 copies/mL. Fifteen associated with improved virologic re- heterozygotes and 1 homozygote for sponse. The association between phar- (Cmax) by 4.7 fold. The authors sug- PD-1.3 and 7 heterozygotes for CCR5 macokinetic parameters and virologic gested that a dose separation strategy Δ32 were identified. Baseline median response appeared to be relevant in the should be tested to overcome this in- CD4+ counts were statistically signifi- lower but not the higher dose group. teraction. cantly lower in patients with PD-1.3 al- Bertz and colleagues presented phar- Agarwala and colleagues (Abstract leles (121 cells/μL, range 5-335) than macokinetic and pharmacodynamic 568) investigated several strategies to patients with wild type (187 cells/μL; data from BMS 424-089, a study com- coadminister famotidine with atazana- range 10-760; P = .02 for the differ- paring ritonavir-boosted atazanavir vir/ritonavir and tenofovir through ence between the 2 CD4+ counts). to unboosted atazanavir with 2 nRTIs pharmacokinetic studies with HIV-se- CD4+ counts were also significantly in treatment-naive subjects (Abstract ronegative volunteers. Four different lower in individuals with the PD-1.3 al- 565). As expected, trough concentra- famotidine dosing strategies led to lele at 2, 4, 6, and 8 months after ini- tion of atazanavir was lower in subjects modest reductions in the minimum tiation of antiretroviral therapy. There receiving unboosted atazanavir than concentration (Cmin) of atazanavir: 20 were no significant differences in viro- subjects receiving boosted atazanavir mg orally twice daily (morning dose logic response between the 2 groups, (125 ng/mL and 663 ng/mL, respective- of famotidine and atazanavir/ritonavir and CCR5 Δ32 did not have an appre- ly). The trough concentration correlat- coadministered) led to a 19% reduc- ciable effect on response to therapy. ed with probability of having a plasma tion, 20 mg orally twice daily (atazana- The results were limited by small sam- HIV-1 RNA level below 50 copies/mL vir/ritonavir and famotidine separated ple size, but suggest that further inves- at week 48 and higher bilirubin lev- by 2 hours) led to an 18% reduction, tigations are needed. els, but did not correlate with changes 40 mg orally once daily (separated by in lipid parameters. The authors sug- 12 hours from atazanavir/ritonavir) led to a 23% reduction, and 40 mg orally Selected Pharmacokinetic gested that the relatively adverse lipid twice daily led to a 28% reduction. Presentations effects seen with boosted atazanavir versus unboosted atazanavir were due Rifampin is known to decrease lev- to ritonavir administration, not due to els of PIs, precluding their coadmin- Antiretroviral Drug Interactions higher atazanavir levels per se. istration. Acosta and colleagues (Ab- Tebas and colleagues (Abstract 572) stract 575) presented data from ACTG Waters and colleagues (Abstract 557) presented data on the pharmacoki- A5213, which studied higher doses of presented data on the interaction of netics of enfuvirtide in patients with atazanavir without ritonavir to over- abacavir with atazanavir/ritonavir and severe renal impairment (defined as come this interaction. Regimens stud- lopinavir/ritonavir in HIV-infected pa- calculated creatinine clearance of 11 ied included atazanavir 300 mg twice tients. The pharmacokinetics of aba- to 35 mL/minute) and patients on he- daily, atazanavir 400 mg twice daily, cavir before and after adding 2 weeks modialysis. They found that the AUC and atazanavir 600 mg twice daily. of either atazanavir/ritoanvir or lopina- of enfuvirtide was higher in patients Even at the highest dose, the trough vir/ritonavir and the pharmacokinetics with renal disease (80.3 µg·h/mL in concentration of atazanavir (55 ng/ of atazanavir/ritonavir or lopinavir/rito- patients with severe renal impairment mL) was statistically significantly lower navir before and after adding abacavir and 71.1 µg·h/mL in patients with than that of historic controls receiving were evaluated. Atazanavir/ritonavir end-stage renal disease [ESRD]) than 400 mg daily (159 ng/mL). Coadminis- and lopinavir/ritonavir levels were not in controls with normal renal function tration of these drugs is therefore not affected by the addition of abacavir, (49.6 µg·h/mL). Despite the higher ex- recommended. however, the AUC (area under the con- posure in patients with renal disease, German and colleagues (Abstract centration curve) of abacavir was de- all patients tolerated enfurviritide well 577) presented data on the interaction creased by 17% after the addition of and no safety concerns were identi- of efavirenz and a leading antimalarial atazanavir/ritonavir and by 32% after fied, therefore no dose adjustment was treatment, artesunate and amodia- the addition of lopinavir/ritonavir. The recommended. quine. The study was stopped early af-

78 International AIDS Society–USA Topics in HIV Medicine

Table 4: Key Findings and Potential Clinical Implications Clinical Trials of Antiretroviral Agents Summary Potential Clinical Implications

Treatment of antiretroviral-experienced patients (Abstracts 104aLB, 104bLB, 105aLB, 105bLB) 2 studies of maraviroc and 2 studies of raltegravir achieved Achieving complete virologic suppression (plasma HIV-1 RNA <50 excellent virologic suppression in highly treatment-expe- copies/mL) is a realistic goal for all patients initiating or changing rienced subjects when using these new agents. The best antiretroviral therapy. responses occured when there were 1 or more active drugs New agents, especially those in new drug classes, are optimally in the optimized background regimen. These drugs appeared given when there is at least 1 other agent to which the patient is safe and well tolerated. sensitive.

Treatment of antiretroviral-naive patients (Abstracts 138, 503, 506, 507) 2 trials examining once-daily regimens, 1 with a once-daily No new once-daily options were evident from the data pre- lopinavir/ritonavir-based regimen and 1 with once-daily nevi- sented, although once-daily lopinavir/ritonavir regimens were rapine regimen had suboptimal virologic response profiles. comparable to twice-daily regimens in individuals with plasma

HIV-1 RNA <5.0 log10 copies/mL.

Antiretroviral treatment strategies (Abstracts 513, 514, 516, 638) Lopinavir/ritonavir de-escalation was associated with contin- Treatment interruption is associated with serious adverse events ued suppression of plasma HIV-1 RNA for >1 year, but nonad- and de-escalation to monotherapy with lopinavir/ritonavir or herence consistently predicted loss of virologic suppression. lamivudine may be alternative short-term options for patients on Lamivudine monotherapy allowed patients with M184V mu- long-term antiretroviral therapy who request treatment interrup- tations to remain off combination antiretroviral therapy for a tion. longer period of time and was associated with fewer adverse events than treatment interruption.

Antiretroviral Resistance Summary Potential Clinical Implications

Transmitted drug resistance (TDR; Abstracts 60, 648, 650, 653, 657) TDR occurs at relatively high frequencies in industrialized Baseline resistance testing in treatment-naive individuals should countries and if undetected can lead to initiation of inactive precede and guide initiation of antiretroviral therapy. antiretroviral medications. The natural history of TDR and its impact on clinical outcomes deserve further evaluation.

Low-frequency resistance variants (Abstracts 61, 639, 658, 666) Low-frequency resistance variants are not detected by Additional studies should be conducted to determine the impact standard resistance testing but appear to affect antiretroviral of low-frequency variants on outcome, and clinical cut-offs for therapy response. sensitive resistance tests should be established. Future standard-of-care may include detection of low-frequency resistance variants to guide antiretroviral therapy but this is too labor intensive and too costly to be incorporated into practice in the near future.

Effect of subtype on resistance (Abstracts 59, 585, 624, 661, 664) Genetic variability of subtypes affects development of resis- Clinicians should know the HIV-1 subtype of their patients, be tance mutations. familiar with resistance mutations associated with this subtype, and take these factors into consideration when choosing antiret- roviral regimens. Additional research should be conducted to evaluate prevalence of resistance mutations among non-B subtypes, and their clinical implications, and databases and resistance algorithms should be updated accordingly.

79 (Continued on next page) Conference Highlights - Advances in Antiretroviral Therapy Volume 15 Issue 2 April/May 2007

Table 4: Key Findings and Potential Clinical Implications (continued)

Novel mutations in HIV-1 reverse transcriptase (Abstracts 90, 593, 594) Mutations in the connection and RNase H domains of HIV-1 Further studies should evaluate the impact of these mutations on reverse transcriptase have only recently been evaluated and resistance and fitness. may represent novel resistance mutations. If these mutations prove to have clinical significance in addi- tion to mutations already identified in the polymerase domain, routine sequencing of the entire HIV-1 reverse transcriptase may become standard in resistance testing.

Antiretroviral Treatment In Resource-limited Settings Summary Potential Clinical Implications Treatment outcomes in large adult cohorts (Abstracts 33, 34, 35, 36LB, 62, 531, 535, 537) In resource-limited settings antiretroviral therapy initiation Addressing early mortality and loss to follow up remain impor- occurs at an advanced disease stage, active case-finding of tant challenges in resource-limited settings. patients lost to follow up is essential, and mortality within the Further options for second-line therapy are urgently needed. first 3 months is high. Appropriate responses to first- and second-line antiretroviral treatment are observed, and adjusted mortality is comparable to that in some European and North American cohorts, but options for second-line therapy are very limited.

Treatment outcomes in large pediatric cohorts (Abstracts 79, 727, 728, 729, 732) Children in resource-limited settings initiate treatment at a Increased access to and earlier initiation of treatment are needed more advanced disease stage and at an older age. for children in resource-limited settings. Response to therapy is encouraging, but anemia and low As recommended by the most recent World Health Organization weight-for-age are predictors of mortality. guidelines, anemia and malnutrition should be considered in the decision to initiate antiretroviral treatment.

Laboratory monitoring in resource-limited settings (Abstracts 538, 531, 629, 673, 674) Neither CD4+ cell count change over time nor a derived No clear alternative to monitoring plasma HIV-1 RNA in resource- failure score performed well as substitutes for plasma HIV-1 limited settings exists. RNA monitoring. Further development of less expensive, simpler assays is needed. Several new techniques for monitoring response to antiret- roviral therapy in resource-limited settings are promising, but filter paper transfer of whole blood may lead to high false- positive rates.

Adherence in resource-limited settings (Abstracts 530, 536, 548) Nonadherence to antiretroviral treatment is high in some Formal screening for adherence and addressing costs such as resource-limited settings. transportation and additional health care expenditures may In addition to factors traditionally associated with decreased improve adherence in resource-limited settings. adherence in non-resource-limited settings, discontinuation of antiretroviral therapy in resource-limited settings may be re- lated to transportation, other health care costs, and depression.

ter 2 of 2 subjects receiving efavirenz Antiretroviral Exposure in Pregnancy. ond and in the third trimester and in and the antimalarial drugs developed Peytavin and colleagues (Abstract 579) nonpregnant controls. Trough levels asymptomatic elevations in transami- conducted a case-controlled study to were statistically significantly lower in nases. The AUC of amodiquine was in- evaluate the effect of pregnancy on pregnant women than in controls (Cmin, creased by 114% and by 302% in the lopinavir/ritonavir pharmacokinetics. 3806 and 3274 ng/mL in the second 2 subjects and was the likely cause of Lopinavir trough levels were monitored and third trimester, respectively, 5122 the hepatitis. in 100 HIV-infected women in the sec- ng/mL in controls). Lower levels have

80 International AIDS Society–USA Topics in HIV Medicine

been associated with inadequate viro- study in Kenya (Abstract 72) is a phase data presented at this year’s confer- logic suppression. In contrast, Khoung- II, open label study providing nevirap- ence clearly demonstrate that public Jones and colleagues (Abstract 743) ine, lamivudine, and zidovudine in HIV- health approaches to delivery of anti- found that lopinavir levels were ad- 1-seropositive women for PMTCT during retroviral therapy in resource-limited equate (Cmin, 5300 ng/mL) in 36 preg- breastfeeding. An analysis of concen- settings can be highly successful. Chal- nant women who received the tablet trations of antiretrovirals in maternal lenges in the field remain formidable formulation of lopinavir/ritonavir. plasma, breast milk, and infant plasma but the basic and clinical research ho- Burger and colleagues (Abstract 741) in the 67 mother-infant pairs enrolled rizons in antiretroviral therapeutics are conducted an uncontrolled study of 14 showed statistically significant variabil- bright, and provide hope that these pregnant women receiving saquinavir ity of concentrations in each compart- challenges can be met for the benefit 1000 mg/ritonavir 100 mg twice daily ment. Maternal plasma and breast-milk of the nearly 40 million HIV-1-infected plus 2 nRTIs. They found that all 14 concentrations of zidovudine were low persons worldwide. women achieved adequate levels of (medians of 23 and 9 ng/mL, respec- tively) and median plasma concentra- saquinavir that were comparable with Financial Disclosures: Dr Jones has no rel- published data. tion in infants was below the assay level evant financial affiliations to disclose. Dr Ripamonti and colleagues (Abstract of detection. Lamivudine concentrations Taylor has no relevant financial affiliations to 742) presented data on 9 pregnant were higher in breast milk and maternal disclose. Dr Wilkin has received grant sup- women receiving atazanavir/ritonavir plasma and the median plasma concen- port from Tibotec and is on the speakers’ bu- during the third trimester of pregnan- tration in infants was 25 ng/mL, equal reau for Merck. Dr Hammer has served as a cy. The pharmacokinetic parameters to the median inhibitory concentration scientific advisor for Progenics, Tibotec, Pfiz- er, and Merck, and is a member of the Data obtained during the third trimester (IC50) but less than the optimal dose for and Safety Monitoring Board for Bristol-My- were similar to those seen at 8 to 16 virologic suppression. Nevirapine con- ers Squibb. weeks postpartum. Cord blood levels centrations in maternal breast milk and of atazanavir were 220 ng/mL, ap- plasma were even higher than that of proximately 10% that of concurrent lamivudine, and median infant plasma A list of all cited abstracts appear maternal plasma levels. Natha and col- concentrations (911 ng/mL) were well on page 83-91. leagues (Abstract 750) collected trough above the IC50 but below the target dose concentrations of atazanavir from 15 for virologic suppression. The authors women receiving atazanavir/ritonavir concluded that providing antiretroviral during pregnancy and found a mean prophylaxis for mothers of breastfeeding Additional References trough level of 421 ng/mL. All but 1 infants may be effective for PMTCT but 1. Desquilbet L, Goujard C, Rouzioux C, et woman were above the minimum tar- there are risks of adverse effects and the al. Does transient HAART during primary get level of 100 ng/mL. possibility of resistance in infants who HIV-1 infection lower the virological set- Read and colleagues (Abstract 740) become infected. The variable pharma- point? AIDS. 2004;18:2361-2369. cokinetics of antiretroviral use in nursing investigated the pharmacokinetics of 2. Hecht FM, Wang L, Collier A, et al. A mul- nelfinavir among women in the third mothers warrants further research. ticenter observational study of the potential trimester of pregnancy compared with benefits of initiating combination antiretro- postpartum levels. Trough concentra- Conclusion viral therapy during acute HIV infection. J tions were lower during pregnancy and Infect Dis. 2006;194:725-733. were suboptimal for most women at both 3. Streeck H, Jessen H, Alter G, et al. Im- time points. In addition, the metabolism This year’s conference maintained its munological and virological impact of of nelfinavir was statistically significantly reputation as the premier forum for highly active antiretroviral therapy initiated altered during pregnancy. The AUC of presentation of new information in during acute HIV-1 infection. J Infect Dis. M8, the virologically active metabolite of the field of antiretroviral therapeutics 2006;194:734-739. nelfinavir, was 80% lower during preg- (see table 4). The likely additions of 4. Johnson VA, Brun-Vezinet F, Clotet B, et al. nancy than postpartum, further compro- maraviroc and raltegravir, represent- Update of the Drug Resistance Mutations in mising the efficacy of this drug. ing 2 new drug classes, to the list of HIV-1: Fall 2006. Top HIV Med. 2006;14:125- FDA-approved antiretroviral drugs will 130. Antiretroviral Concentrations in improve our ability to maintain maxi- Breastfeeding Infants. Substantial evi- mum virus suppression even in highly 5. Bertagnolio S, Soto-Ramirez L, Pilon R, et al. HIV-1 drug resistance genotyping in treat- dence was presented at this year’s treatment-experienced patients. In ad- ment naive subjects using dried whole blood conference that formula feeding as a dition, further clinical research involv- spots. [Abstract THAX0103.] 16th Interna- strategy for PMTCT of HIV is associat- ing these agents and others in their tional AIDS Conference. August 13-18, 2006; ed with a higher rate of mortality than classes may well change current para- Toronto, Canada. is breastfeeding (see “HIV Epidemiol- digms of therapy. Although the com- 6. De Cock KM, Fowler MG, Mercier E, et ogy and Prevention Interventions” in plexity of antiretroviral therapy and al. Prevention of mother-to-child HIV trans- this issue). The Kisumu breastfeeding HIV-1 drug resistance is increasing, mission in resource-poor countries: translat-

81 Conference Highlights - Advances in Antiretroviral Therapy Volume 15 Issue 2 April/May 2007

ing research into policy and practice. JAMA. High prevalence of the K65R mutation in hu- virenz-containing regimens for the initial 2000;283:1175-1182. man immunodeficiency virus type 1 subtype treatment of HIV-1 infection. N Engl J Med. C isolates from infected patients in Botswana 2004;350:1850-1861. 7. Hemelaar J, Gouws E, Ghys PD, Osmanov treated with didanosine-based regimens. An- S. Global and regional distribution of HIV-1 timicrob Agents Chemother. 2006;50:4182- genetic subtypes and recombinants in 2004. 4185. 16. Lloyd R, Huong J, Rouse E, et al. HIV-1 RT AIDS. 2006;20:W13-W23. mutations K70E and K65R are not present on 12. Brenner BG, Oliveira M, Doualla-Bell F, 8. Grossman Z, Paxinos EE, Averbuch D, et the same viral genome when both mutations et al. HIV-1 subtype C viruses rapidly develop al. Mutation D30N is not preferentially select- are detected in plasma. [Abstract H-1006.] K65R resistance to tenofovir in cell culture. ed by human immunodeficiency virus type 1 45th Interscience Conference on Antimicro- AIDS. 2006;20:F9-F13. subtype C in the development of resistance bial Agents and Chemotherapy. December to nelfinavir. Antimicrob Agents Chemother. 13. Gallant JE, Rodriguez AE, Weinberg WG, 16-19, 2005; Washington, DC. 2004;48:2159-2165. et al. Early virologic nonresponse to tenofo- 9. Gonzalez LM, Brindeiro RM, Aguiar RS, et vir, abacavir, and lamivudine in HIV-infected 17. Nikolenko GN, Palmer S, Maldarelli F, antiretroviral-naive subjects. J Infect Dis. al. Impact of nelfinavir resistance mutations on Mellors JW, Coffin JM, Pathak VK. Mechanism 2005;192:1921-1930. in vitro phenotype, fitness, and replication ca- for nucleoside analog-mediated abrogation pacity of human immunodeficiency virus type 14. Parikh UM, Koontz DL, Chu CK, Schinazi of HIV-1 replication: balance between RNase 1 with subtype B and C proteases. Antimicrob Agents Chemother. 2004;48:3552-3555. RF, Mellors JW. In vitro activity of structurally H activity and nucleotide excision. Proc Natl diverse nucleoside analogs against human im- Acad Sci U S A. 2005;102:2093-2098. 10. Grossman Z, Istomin V, Averbuch D, et al. munodeficiency virus type 1 with the K65R Genetic variation at NNRTI resistance-associ- mutation in reverse transcriptase. Antimicrob ated positions in patients infected with HIV-1 Agents Chemother. 2005;49:1139-1144. subtype C. AIDS. 2004;18:909-915. 15. Gulick RM, Ribaudo HJ, Shikuma CM, Top HIV Med. 2007;15: 48-82 11. Doualla-Bell F, Avalos A, Brenner B, et al. et al. Triple-nucleoside regimens versus efa- ©2007, International AIDS Society–USA

Drug Resistance Mutations Figures

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