Use of the Oral Neuraminidase Inhibitor Oseltamivir in Experimental Human Influenza Randomized Controlled Trials for Prevention and Treatment

ORIGINAL CONTRIBUTION

Frederick G. Hayden, MD Context Influenza virus neuraminidase is thought to be essential for virus replica- John J. Treanor, MD tion in humans; however, to date, available neuraminidase inhibitors are limited to zanamivir, which is topically administered. R. Scott Fritz, PhD Objective To determine the safety, tolerability, and antiviral activity of oral neur- Monica Lobo, MD aminidase inhibitor oseltamivir (GS4104/Ro64-0796) for prevention and the early treat- Robert F. Betts, MD ment of influenza in experimentally infected humans. Madeline Miller, DVM Design Two randomized, double-blind, placebo-controlled trials conducted between June and July 1997. Nelson Kinnersley, MSc Setting Individual hotel rooms; 2 large US university medical schools. Roger G. Mills, MD Participants A total of 117 healthy adult volunteers (aged 18-40 years; median age, Penelope Ward, MD 21 years) who were susceptible (hemagglutination-inhibition antibody titer Յ1:8). Stephen E. Straus, MD Interventions All subjects were inoculated intranasally with influenza A/Texas/36/91 (H1N1) virus. For the prophylaxis study, oral oseltamivir (100 mg once daily [n = 12], 100 CONTINUING NEED EXISTS FOR mg twice daily [n = 12], or matching placebo [n = 13], starting 26 hours before virus in- antiviral agents against influ- oculation) was administered. For the treatment study, the same drug was given (20 mg, enza A and B virus infections 100 mg, or 200 mg twice daily, 200 mg once daily, or matching placebo [n = 16], in each for treatment of influenza and group starting 28 hours after inoculation). All regimens were continued for 5 days. asA a supplementation to vaccines for Main Outcome Measures Comparing placebo groups with pooled treatment groups, prevention. The influenza virus neur- for prophylaxis, outcomes included frequency of infection and viral shedding; for treat- aminidase is 1 of 2 major surface glyco- ment, viral shedding in titers. proteins of influenza A and B viruses. Results In the prophylaxis study, 8 (67%) of 12 placebo and 8 (38%) of 21 oselta- It cleaves terminal sialic acid (N- mivir recipients became infected (P = .16; efficacy, 61%); 6 (50%) placebo compared acetylneuraminic acid) residues from with 0 oseltamivir recipients shed virus (PϽ.001; efficacy, 100%), and 33% of pla- cellular and viral glycoconjugates and is cebo but no oseltamivir recipient had infection-related respiratory illness (PϽ.01). Among essential for sustained viral replication infected subjects in the treatment study (n = 69), the viral titer area under the curve of in vitro1 and probably also in humans.2 the combined oseltamivir groups (n = 56) was lower (median [interquartile range {IQR}], ϫ Inhibition of neuraminidase enzymatic 80 [23-151] vs 273 [79-306] log10 tissue culture-infective doses50 per milliliter hour; action by antibody, mutation, or chemi- P = .02) than the placebo group (n = 13), and the median (IQR) duration of viral shedding with therapy was reduced from 107 (83-131) to 58 (35-59) hours (P = .003). Os- cals causes virus particles to aggregate eltamivir treatment also reduced symptom scores (median [IQR] score-hours, 225 [97- at the cell surface and with each other. 349] vs 400 [189-645]; P = .05), and nasal proinflammatory cytokine levels. Transient In addition, neuraminidase prevents in- mild to moderate nausea after dosing was observed in 15 (17%) of 88 oseltamivir activation of influenza virus by respira- and 2 (7%) of 29 placebo recipients (95% confidence interval for difference, −11% tory mucus and likely facilitates infec- to 68%), which was largely prevented by ingestion with food. 3 tion of the airway mucosa. The enzyme Conclusions In these trials, prophylaxis and early treatment with oral oseltamivir were active site is highly conserved across in- both associated with significant antiviral and clinical effects in experimental human influenza. 4-6 fluenza A and B viruses, and several JAMA. 1999;282:1240-1246 www.jama.com novel antiviral compounds have been de- Author Affiliations and Financial Disclosures are listed MD, University of Virginia Health Sciences Center, De- signed based on the neuraminidase crys- at the end of this article. partment of Internal Medicine, Box 473, Charlottes- tallographic structure.5,7 CorrespondingAuthorandReprints: FrederickG.Hayden, ville, VA 22908 (e-mail: [email protected]).

Downloaded From: https://jamanetwork.com/ on 09/26/2021 ORAL OSELTAMIVIR IN EXPERIMENTAL INFLUENZA

The neuraminidase inhibitor zanami- to the challenge virus on the basis of istration began at 28 hours after inocu- vir (or GG167) has been shown previ- having serum hemagglutination- lation and continued for 5 days. Because ously to have anti-influenza activity in inhibition antibody titers with a dilu- of the large numbers of subjects in the experimentally infected animals7-9 and tion of 1: 8 or less. Those with concur- treatment study, it was conducted in 2 humans.2 Inhaled zanamivir provides rent medication use or illness within 1 sessions separated by 1 week. Drug was clinical benefit in adults with acute, un- week were excluded. Only nonsmok- administered under direct observation complicated influenza.10,11 However, the ers or those smoking fewer than 10 ciga- ofthestudynursestoensurecompliance. low oral bioavailability, small volume of rettes daily who agreed to abstain dur- Computer-generated code was used to distribution, and rapid renal elimination ing the study were included. Written randomize subjects. The code remained of zanamivir12 has limited its administra- informed consent was obtained from unbroken until all results had been col- tion to topical (intranasal and/or inhaled) each participant in a form approved by lected and entered into the final database. routesofdeliveryinhumanstudies.These the institutional review boards of the Nasal washings were collected be- topical routes are not easily used by many University of Virginia, Charlottesville, fore viral inoculation for detecting res- patients, including persons who are in- and the University of Rochester, Roch- piratory viruses by standard tech- firm and young children, and distribu- ester, NY, and subjects were compen- niques and then each morning for tion of the drug is not uniform through- sated for participation. influenza virus isolation in freshly in- out the respiratory tract.13 Effective Using previously described meth- oculated Madin Darby canine kidney delivery of the drug to both upper and ods,2,22,23 the subjects were isolated in monolayers. Washings were also col- lower respiratory tracts may be impor- individual hotel rooms 1 day before lected each evening on days 2 and 3 af- tant for reducing complications and vi- inoculation until 8 days after inocula- ter challenge in the treatment study. ral transmission. Consequently, consid- tion. They were inoculated by intrana- Frozen aliquots from samples that were erable interest exists in developing oral sal drops (0.25 mL per nostril) with positive on initial isolation were sub- inhibitors of influenza neuraminidase. approximately 106 median tissue culture- sequently titered in Madin Darby ca- A carbocyclic transition state analog infectious doses (tissue culture- nine kidney cells. Prechallenge and con- of sialic acid cleavage, GS4071/Ro64- infective doses50) of a safety-tested pool valescent (3-4 weeks after inoculation) 0802 (3R,4R,5S-4-acetamido-5-amino- of influenza A/Texas/36/91(H1N1) vi- serum samples were tested for hemag- 3-[1-ethylpropoxy]-1-cyclohexene-1- rus (provided by the National Institute glutination-inhibition antibodies to the carboxylicacid)iscomparablewithzana- of Allergy and Infectious Diseases, challenge virus. mivir in potency and selectivity under Bethesda, Md). This virus was readily Nasal washings collected before viral invitroconditions.14-16 AlthoughGS4071 inhibited by GS4071 in Madin Darby ca- inoculation and on days 2, 4, and 8 is poorly absorbed, oral administration nine kidney cells (50% plaque inhibi- after inoculation were processed for cy- of the ethyl ester prodrug oseltamivir tory concentration Ͻ0.1 µg/mL) and in tokine determinations as previously de- phosphate (GS4104/Ro64-0796) gives explants of human respiratory epithe- scribed.24 Cytokine levels were deter- good bioavailablity of GS4071 in mul- lium (90% yield inhibitory concentra- mined using commercially available tiple species.17 Oral oseltamivir is active tion Ͻ0.01 µg/mL) in vitro.16 enzyme-linked immunosorbent assay in murine and ferret models of influ- kits and the manufacturer’s protocols. enza.18,19 In the rat, oral oseltamivir Study Design The kits were obtained from the follow- provides prolonged levels of the parent Tworandomized,double-blind,placebo- ing sources: interleukin (IL) 5, IL-6, in- compound GS4071 in lung tissue and controlled, dose-ranging trials were con- terferon alfa (IFN-␣), and IFN-␥ (En- bronchoalveolar lavages.20 In humans, ducted in parallel to test the prophylac- dogen Inc, Cambridge, Mass); tumor oral oseltamivir is associated with dose- tic and early therapeutic activity of oral necrosis factor alpha (TNF-␣) (R&D proportionalincreasesinplasmaGS4071 oseltamivir capsules. The placebo cap- Systems Inc, Minneapolis, Minn). The concentrations and a prolonged plasma sules were identical in appearance. In the limits of sensitivity of these assays, as GS4071 half-life (7-9 hours), which al- prophylaxis study (University of Roch- supplied by the manufacturers, were lows for infrequent dosing.21 The objec- ester), individual volunteers were as- as follows: IL-5 (Ͻ2 pg/mL), IL-6 (Ͻ1 tives of our study were to determine the signed to 1 of 3 treatment groups: 100 pg/mL), IFN-␣ (Ͻ3 pg/mL), IFN-␥ (Ͻ2 safety, tolerability, and antiviral activ- mg once daily (n = 12), 100 mg twice pg/mL), and TNF-␣ (Ͻ0.18 pg/mL). ity of oral oseltamivir for the prevention daily (n = 12), or placebo (n = 13). Ad- Oral temperatures were recorded 4 and early treatment of influenza in ex- ministration began 26 hours prior to vi- times daily, and 14 symptoms (nasal perimentally infected volunteers. ral inoculation and continued for 5 days. stuffiness, runny nose, sore throat, In the treatment study (University of Vir- sneezing, cough, breathing difficulty, METHODS ginia), the volunteers were assigned to muscle aches, fatigue, headache, earache/ Volunteers and Infection 1 of 5 treatment groups (n = 16 per pressure, feverishness, hoarseness, chest The subjects were healthy adults aged group): 20, 100, or 200 mg twice daily, discomfort, overall discomfort) were 18 to 40 years who were susceptible 200 mg once daily, or placebo. Admin- scored by the subjects twice daily on a

Downloaded From: https://jamanetwork.com/ on 09/26/2021 ORAL OSELTAMIVIR IN EXPERIMENTAL INFLUENZA

4-point scale (absent to severe). Rhi- ache) of moderate or severe intensity time to cessation of viral shedding, to- norrhea was assessed by measuring na- occurring on 1 or more days after chal- tal symptom score AUC, nasal mucus sal mucus weights; middle-ear pres- lenge. Lower respiratory tract illness weights, frequencies of upper respira- sure abnormalities were assessed by was defined by the presence of cough tory tract illness, cough, fever, middle digital tympanometry completed once of moderate or severe intensity on 1 or ear pressure abnormalities, and concen- daily.23 Routine safety laboratory stud- more days after challenge. Fever was de- trations of cytokines in nasal lavage flu- ies (complete blood cell counts, differ- fined by a confirmed oral temperature ids. The time to alleviation of illness was ential leukocyte count, platelets, uri- of 37.8°C or higher. defined as the time from the beginning nalysis, serum electrolytes, calcium, In the prophylaxis study, the pri- of the study treatment to the time that phosphorus, urea, creatinine, glucose, mary outcomes of interest were the fre- 7 key symptoms typical of natural in- total protein, albumin, amylase, uric quencies of viral shedding and infec- fluenza had reduced to absent or mild. acid, triglycerides, cholesterol, aspar- tion. The secondary outcomes were the Similarly, the time to cessation of viral tate aminotransferase, alanine transami- symptom scores over time and the fre- shedding was defined from the begin- nase, glutamic-oxaloacetic transami- quencies of infection-associated fever and ning of the study treatment. Sample sizes nase, alkaline phosphatase, bilirubin, upper respiratory tract illness. Sample were based on prior findings with this creatine phosphokinase, and lactate sizes were based on prior findings with virus and zanamivir treatment.2 With 16 dehydrogenase) were performed at this virus and zanamivir administra- subjects per group, a comparison of pla- baseline and following completion of tion.2 With 14 subjects per group, a com- cebo vs pooled oseltamivir groups had drug dosing. Acetaminophen was al- parison of placebo vs the pooled active 80% power to detect a significant dif- lowed for fever and discomfort. treatments had an 80% power to detect ference (2-sided, 5% level) of 4.0 log10 a significant difference (2-sided, 5% level) tissue culture-infective doses50 per Outcomes between infection or virus shedding rates milliliter ϫ days in the viral titer AUCs Infection was defined by a positive cul- of 80% in those taking the placebo vs (SD, 5.5 log10 tissue culture-infective ϫ ture for influenza virus on 1 or more 30% taking active drug. doses50 per milliliter days). postinoculation days and/or 4-fold or In the treatment study, the primary greater increase in serum hemaggluti- outcome measure was the quantity of vi- Data Analysis nation-inhibition antibody titer. Up- rus shed over time in nasal washings. A 2-sided Fisher exact test was used for per respiratory tract illness was de- This was calculated as an area under the comparison of infection rates between fined as 2 or more respiratory symptoms curve (AUC) for viral titers over the 7 placebo and the pooled oseltamivir (nasal stuffiness, runny nose, sore days after treatment initiation. The sec- groups and a Wilcoxon rank-sum test throat, sneezing, hoarseness, and ear- ondary efficacy end points included the was used to compare differences in viral titer AUC values. The time to cessation of viral shedding and the time to al- Figure 1. Prophylaxis and Treatment Trials leviation of symptoms were compared using a generalized Gehan-Wilcoxon Prophylaxis Trial Treatment Trial test. To compare the percentage of sub- Registered Patients, n = 37 Registered Patients, n = 80 jects in the placebo group and active dose groups exhibiting gastrointestinal tract

Randomization, n = 37 Randomization, n = 80 events during the dosing period, exact 95% confidence intervals were calculated according to the method of Santer Received Oseltamivir, Received Placebo, Received Oseltamivir, Received Placebo, 25 n = 24 n = 13 n = 64 n = 16 and Snell. Sample size calculations were performed using statistical software

Completed Drug Completed Drug Completed Drug Completed Drug (PASS 6.0, NCSS, Kaysville, Utah). Administration, n = 24 Administration, n = 13 Administration, n = 64 Administration, n = 16 RESULTS

Evaluable for Safety, Evaluable for Safety, Evaluable for Safety, Evaluable for Safety, Volunteers n = 24 n = 13 n = 64 n = 16 The 2 trials enrolled a total of 117 participants, most of whom were young Evaluable for Efficacy, Evaluable for Efficacy, Evaluable for Efficacy, Evaluable for Efficacy, n = 21 n = 12 n = 56 n = 13 (median age, 21 years). There were no Not Evaluable for Efficacy Not Evaluable for Efficacy Not Evaluable for Efficacy, Not Evaluable for Efficacy dropouts and all subjects completed the Baseline HAI Ab Titer Baseline HAI Ab Titer n = 8 Not Infected, n = 3 >1:8, n = 3 >1:8, n = 1 Not Infected, n = 7 full course of drug administration. In the Intercurrent Illness, n = 1 prophylaxis study, 4 subjects (3 oseltamivir, 1 placebo) were excluded from ef- HAl Ab indicates hemagglutination inhibition antibody. ficacy analysis because of baseline hem-

Downloaded From: https://jamanetwork.com/ on 09/26/2021 ORAL OSELTAMIVIR IN EXPERIMENTAL INFLUENZA

agglutination-inhibition antibody titers dian time to cessation of viral shed- 200-mg once daily group had a higher with a dilution of more than 1: 8. In the ding was reduced from 107 hours in the viral titer AUC value compared with the treatment study, 11 subjects (8 oselta- placebo group to 58 hours in the com- twice daily dose groups (TABLE). mivir, 3 placebo) were excluded be- bined oseltamivir group (P = .003). No This antiviral effect was associated cause of lack of documented infection significant differences in these virologi- with significant reductions in illness or of intercurrent viral illness (1 oselta- cal measures were observed across the burden and biochemical markers of mivir) (FIGURE 1). All volunteers were oseltamivir dose groups, although the host inflammatory responses in the res- included in the analysis of safety.

Prophylactic Activity Figure 2. Effect of Oral Oseltamivir Prophylaxis on Illness Following Experimental Influenza A/Texas/36/91(H1N1) Inoculation Among the 12 evaluable placebo re-

cipients, 6 (50%) had recovery of the 4.0 Drug Administration challenge virus from nasal washings and 8 (67%) had laboratory-confirmed in- 3.5 fection. In contrast, none of the 21 evaluable oseltamivir recipients had vi- 3.0 rus isolated (PϽ.001; 100% efficacy) Placebo and only 8 (38%), 4 in each dose group, 2.5 had serologic evidence of infection (P= .16; 61% efficacy). This antiviral ef- 2.0

fect was associated with reductions in 1.5 illness measures. Symptom scores over

time did not change significantly after Symptom Score Median Total 1.0 viral inoculation in the oseltamivir group, in contrast to the expected peak 0.5 Oseltamivir 2 days after challenge in the placebo group (FIGURE 2). Infection-associ- 0.0 ated upper respiratory tract infection –12 0 12 24 36 48 60 72 84 96 108 120 132 144 156 Time, h developed in 4 subjects (33%) taking Inoculation placebo but in none of the subjects tak- The total symptom score area under the curve value was lower in the combined oseltamivir groups (n = 21) ing oseltamivir (P = .01). Fever was ob- compared with placebo (n = 12); P = .02. Fourteen symptoms related to influenza were included in the score. served in 3 (25%) and cough in 2 (16%) placebo recipients. No important dif- Figure 3. Effect of Oral Oseltamivir Treatment on Vital Titers in Nasal Lavages Following ferences were observed between the Experimental Influenza A/Texas/36/91(H1N1) Infection once and twice daily oseltamivir dose groups. 4.5 Drug Administration

Therapeutic Activity 4.0

Only the 69 subjects (56 oseltamivir, 3.5 13 placebo) with laboratory-docu- 3.0 mented infection were included in the Placebo

analysis of therapeutic efficacy. Drug 2.5 administration was initiated at a time when viral titers were increasing 2.0 (FIGURE 3). Peak viral titers were ob- 1.5 served about 11⁄2 days after challenge Tissue Dose per Milliliter Culture-Infective Oseltamivir (12 hours after starting study drug) in 10 1.0 both groups and tended to be lower in the oseltamivir recipients. At 24 and 36 0.5

hours after initiating study drugs, the Median log 0.0 median viral titers were reduced by 2.1 –36 –24 –12 0 12 24 36 48 60 72 84 96 108 120 132 144 156 Time, h log10 and 3.5 log10, respectively, in the Inoculation combined oseltamivir group compared with placebo (P = .02 by AUC The viral titer area under the curve value was lower in the combined oseltamivir group (n = 56) compared with placebo (n = 13); P = .02. analysis). Correspondingly, the me-

Downloaded From: https://jamanetwork.com/ on 09/26/2021 ORAL OSELTAMIVIR IN EXPERIMENTAL INFLUENZA

Table. Dose-Related Antiviral and Clinical Effects of Early Oseltamivir Treatment in Experimental Influenza A/Texas/36/91(H1N1) Infection* Oseltamivir Dose

20 mg 100 mg 200 mg 200 mg Combined P Clinical Effects Twice Daily Twice Daily Twice Daily Once Daily Oseltamivir Placebo Value No. of infected subjects 15 14 14 13 56 13 NA Vital titer†‡ 51 (16-162) 54 (8-105) 85 (48-128) 143 (39-160) 80 (23-151) 273 (79-306) .02 Time to cessation of shedding, h 58 (23-83) 47 (34-59) 58 (35-59) 59 (35-83) 58 (35-59) 107 (83-131) .003 Total symptom score† 231 (72-332) 232 (99-354) 209 (106-354) 235 (63-318) 225 (97-349) 400 (189-645) .05 Nasal mucus weight, g 9 (7-13) 9 (5-12) 8 (6-10) 9 (6-17) 9 (6-13) 20 (9-29) .02 No. (%) with a fever 2 (13) 2 (14) 1 (7) 3 (23) 8 (14) 4 (31) NA *Values listed as median (25%-75% interquartile range) unless otherwise specified. The data for vital titer, total symptom score, and nasal mucus weight reflect events after initiation of drug treatment. NA indicates not applicable. P values refer to comparisons of combined oseltamivir group with placebo group. †Based on area under the curve. ‡Log10 median tissue culture-infective dose multiplied by hour per milliliter. TNF-␣, and IFN-␥ exhibited similar Figure 4. Effect of Oral Oseltamivir Treatment on Illness Following Experimental Influenza patterns in that peak responses oc- A/Texas/36/91(H1N1) Infection curred on day 4 after inoculation in each

8 Drug Administration instance (FIGURE 5). The magnitude of the median of the IL-6, TNF-␣, and 7 IFN-␥ responses were comparable, exhibiting a 4-, 2- and 3-fold increase 6 above baseline, respectively, on this day. By Spearman rank analysis, the in- 5 creases in nasal lavage fluid of IL-6 and IFN-␥ levels correlated significantly 4 Յ Placebo (P .01) with viral titers on days 3 (co- efficients: IL-6, 0.71; IFN-␥, 0.78) and 3 5 (0.77 and 0.67, respectively) among

2 Oseltamivir placebo recipients. In contrast, oselta-

Median Total Symptom Score Median Total mivir treatment significantly reduced 1 these responses, and no changes were observed in oseltamivir recipients over 0 the course of the study. The IFN-␣ re- –36 –24 –12 0 12 24 36 48 60 72 84 96 108 120 132 144 156 Time, h sponse did not show a significant el- Inoculation evation over the course of the infec- The total symptom score area under the curve value was lower in the combined oseltamivir groups (n = 56) tion, and there was no detectable IL-5 compared with placebo (n = 13); P = .05. response in either group.

Tolerance piratory tract. Total symptom scores 54%), middle ear pressure abnormali- No dose-limiting intolerance was ob- peaked at a lower level and resolved ties (28% vs 54%), and fever (14% vs served, and all subjects completed the more rapidly in the combined oselta- 31%) also were lower in oseltamivir re- dosing regimen. The overall fre- mivir group compared with placebo cipients. Among oseltamivir recipi- quency of adverse events during dos- (FIGURE 4). The median time to reso- ents, fever occurred most often in the ing did not differ across the groups, but lution of illness was 53 hours in the os- single daily dose group (23%) and least gastrointestinal tract complaints oc- eltamivir group compared with 95 often in the 200-mg twice daily dose curred more often in the oseltamivir re- hours in the placebo group (P = .03). group (7%). Acetaminophen was used cipients (16 [18%] of 88 compared with Nasal mucus weights were lower by ap- by 69% of placebo and 32% of oselta- 2 [7%] of 29 placebo recipients) dur- proximately 50% in the oseltamivir mivir recipients during the study for ing drug administration (95% confi- group compared with placebo (P = .02) symptom relief, but the majority of sub- dence interval for difference, −11% to (Table). No important dose-related dif- jects took only single doses. The fre- 68%). These were largely manifested as ferences were noted in the principal quency of cough was low in both groups transient nausea of mild to moderate in- clinical outcomes (Table). The frequen- (Ͻ10%). tensity (15 [17%] of 88 oseltamivir re- cies of other measures including up- Among infected placebo recipients, cipients). Emesis (4 [5%] of 88 oselta- per respiratory tract illness (18% vs the median nasal lavage levels of IL-6, mivir recipients) and diarrhea (1 case)

Downloaded From: https://jamanetwork.com/ on 09/26/2021 ORAL OSELTAMIVIR IN EXPERIMENTAL INFLUENZA

were uncommon. Nausea occurred pri- We recently reported that the nasal We did not observe clear dose- marily after the first dose and usually lavage fluid levels of IL-6 and TNF-␣ in- related differences in antiviral effects in resolved within 1 to 2 days despite con- crease in humans experimentally in- the treatment or prophylaxis studies. Al- tinued dosing. In the treatment study, fected with influenza A virus and cor- though once daily dosing may have been gastrointestinal tract upset was ob- relate with the clinical and virological associated with less pronounced antivi- served more often in subjects receiv- features of the illness.24 In this study, we ral effects, our sample sizes were insuf- ing 200-mg doses (9 [28%] of 32 confirm these earlier observations and ficient to make firm conclusions. With compared with 3 [11%] of 32 receiv- also document increases in levels of respect to prophylaxis, an antiviral dose ing lower doses) and in the fasting state IFN-␥ that parallel the increases in IL-6 that allows for a subclinical but immu- (11 [31%] of 36 compared with 2 [7%] and TNF-␣. Among placebo recipi- nizing infection would be optimal. Un- of 28 subjects when administered with ents, the increases in levels of IL-6 and der similar conditions, intranasal zana- food). No significant changes were seen IFN-␥ correlated with viral titers. This mivir prophylaxis completely protected in clinical laboratory parameters (data study verifies our previous findings of against experimental infection in most not shown). the role of IL-6, TNF-␣, and IFN-␥ in subjects, so that protective serologic re- the pathogenesis of symptom produc- sponses were not observed.2 With os- COMMENT tion in influenza and shows that oral oseltamivir prophylaxis, both once and Oral administration of the neuramini- eltamivir also reduced these objective twice daily administration protected dase inhibitor oseltamivir provided sig- markers of host inflammatory re- against viral shedding but allowed some nificant antiviral, biochemical, and clini- sponses. These results further substan- cal effects in experimental human tiate the links between virus replica- Figure 5. Median Nasal Lavage Fluid Levels influenza virus infection. Prophylactic tion, cytokine elaboration, and symptom of Interleukin 6, Interferon Gamma, and administration either once or twice daily production during acute influenza. Tumor Necrosis Factor Alpha in Volunteers completely protected against viral recov- Oral oseltamivir was generally well- Experimentally Infected With Influenza ery in the upper respiratory tract and tolerated in these studies. Both GS4071 A/Texas/36/91(H1N1) against infection-associated respira- and zanamivir are selective inhibitors Interleukin 6 tory tract illness. Early treatment resulted of influenza neuraminidase at low- Drug Administration 12 ∗ in statistically significant reductions in nanomolar concentrations and show Placebo the magnitude and duration of viral rep- negligible activity against neuramini- 9 lication and in the severity and dura- dases from human, bacterial, or other vi- 6

tion of influenza illness. The magni- ral sources at concentrations up to 1 pg/mL Oseltamivir tude of these effects is comparable with mmol/L.14,15 In initial human testing, oral 3

those observed earlier in studies of intra- oseltamivir given while fasting was tol- Median Concentration, 0 nasal zanamivir tested against the same erated at single doses up to 1000 mg or challenge virus under similar condi- repeated doses up to 500 mg twice daily Tumor Necrosis Factor Alpha 2 21 tions. In addition, the magnitude of the for 7 days (total of 13 doses). The high- 0.6 Drug Administration ∗ antiviral effects observed in these stud- est doses, particularly repeated doses of 0.5 Placebo ies exceeded those reported histori- 500 mg, were associated with nausea of 0.4 cally with the influenza A–specific inhibi- mild to moderate intensity. In the cur- 0.3

pg/mL Oseltamivir Concentration, tors amantadine and rimantadine in rent studies, transient nausea after dos- 0.2 experimental human influenza.26-31 Both ing was observed mainly at the highest 0.1 topical zanamivir10,11 and oral adaman- (200 mg) dose and was largely pre- Median 0.0 taneamines32-35 have been shown to pro- vented by administering doses with food. vide clinical benefits in treating uncom- The early timing of onset and the find- Interferon Gamma 12 Drug Administration † plicated influenza, and prophylaxis with ing that ingestion with food largely Placebo amantadine or rimantadine also pro- prevented this adverse effect suggest that 9

vides substantial protection against epi- it might be due to direct gastric irrita- 6 36

demic influenza A illness. Such find- tion, although further studies of the pg/mL Oseltamivir ings predict that oral oseltamivir should mechanism are needed. Of note, admin- 3 ‡ be associated with both prophylactic and istration after food is associated with a Median Concentration, 0 therapeutic activity when studied in modest increase in GS4071 bioavailabil- –36–12 12 36 60 84 108 132 156 Time, h natural influenza. Indeed, recently com- ity.21 These observations suggest that Inoculation

pleted field studies have confirmed the this formulation of oseltamivir should Cytokine levels for days 1, 3, 5, and 9 were deter- efficacy of oral oseltamivir for both sea- be administered with food when pos- mined using commercially available enzyme-linked im- sonal prophylaxis 37 and therapy of acute sible to reduce the risk of gastrointesti- munosorbent assay kits. Asterisk indicates PՅ.01; dagger, PՅ.001; and double dagger, PϽ.05. influenza.38,39 nal tract upset.

Downloaded From: https://jamanetwork.com/ on 09/26/2021 ORAL OSELTAMIVIR IN EXPERIMENTAL INFLUENZA

subjects to develop antibodies. Whether antiviral agent when administered tional Institute of Allergy and Infectious Diseases, Na- tional Institutes of Health, Bethesda, Md (Dr Straus). lower doses might be protective against orally for prevention and treatment of Financial Disclosure: Dr Hayden is a paid consultant illness but allow immune responses re- experimental influenza A infections. for F. Hoffmann-La Roche Ltd (Basel, Switzerland) and Gilead Sciences (Foster City, Calif). Dr Treanor is a paid mains to be determined. Of note, the This agent is a promising new drug consultant for F. Hoffmann-La Roche. findings in these studies guided dose se- for the management of natural influ- Funding/Support: These studies were funded by grants enza. from F. Hoffman-LaRoche Ltd (Basel, Switzerland) and lection for subsequent field trials. The in part with federal funds from the National Cancer initial results from these studies indi- Institute, National Institutes of Health (Bethesda, Md), cate that once daily dosing (75 mg) is Author Affiliations: University of Virginia School of under contract NO1-CO-56000. Medicine, Charlottesville (Drs Hayden and Lobo); Uni- Disclaimer: The content of this article does not nec- safe and effective for long-term prophy- versity of Rochester School of Medicine, Rochester, NY essarily reflect the views or policies of the Department laxis 37 and twice daily dosing (75 mg) (Drs Treanor and Betts); SAIC Frederick, National Can- of Health and Human Services, nor does the mention cer Institute-Frederick Cancer Research and Develop- of trade names, commercial products, or organiza- for short-term treatment of natural ment Center, Frederick, Md (Dr Fritz); Gilead Sci- tions imply endorsement by the US government. influenza in adults.38,39 ences, Foster City, Calif (Drs Miller and Mills); Roche Acknowledgment: The authors thank the study par- Discovery Welwyn, Hoffman-LaRoche and Com- ticipants, the research staff who conducted these stud- In summary, the present studies pany, Welwyn Garden City, England (Mr Kinnersley and ies, and Diane Ramm for helping with manuscript showed oseltamivir to be an effective Dr Ward); and Laboratory of Clinical Investigation, Na- preparation.

REFERENCES 1. Liu C, Eichelberger MC, Compans RW, Air GM. In- activity. J Am Chem Soc. 1997;119:681-690. influenza. JAMA. 1970;213:1448-1454. fluenza type A virus neuraminidase does not play a 15. Mendel DB, Tai CY, Escarpe PA, et al. Oral ad- 28. Reuman PD, Bernstein DI, Keefer MC, Young EC, role in viral entry, replication, assembly, or budding. ministration of a prodrug of the influenza virus neur- Sherwood JR, Schiff GM. Efficacy and safety of low J Virol. 1995;69:1099-1106. aminidase inhibitor GS4071 protects mice and fer- dosage amantadine hydrochloride as prophylaxis for 2. Hayden FG, Treanor JJ, Betts RF, Lobo M, Esin- rets against influenza infection. Antimicrob Agents influenza A. Antiviral Res. 1989;11:27-40. hart JD, Hussey EK. Safety and efficacy of the neur- Chemother. 1998;42:640-646. 29. Jackson GG, Muldoon RL, Akers LW. Serological aminidase inhibitor GG167 in experimental human in- 16. Hayden FG, Rollins BS. In vitro activity of the neur- evidence for prevention of influenzal infection in vol- fluenza. JAMA. 1996;275:295-299. aminidase inhibitor GS4071 against influenza vi- unteers by an anti-influenzal drug adamantanamine hy- 3. Burnet FM. Mucins and mucoids in relation to in- ruses. Antiviral Res. 1997;34:A86. drochloride. Antimicrob Agents Chemother. 1963;3: fluenza virus action, III: inhibition of virus haemag- 17. Li W, Escarpe PA, Eisenberg EJ, et al. Identifica- 703-707. glutination by glandular mucins. Aust J Exp Biol Med tion of GS4104 as an orally bioavailable prodrug of 30. Dawkins ATJ, Gallager LR, Togo Y, Hornick RB, Sci. 1948;26:371-379. the influenza virus neuraminidase inhibitor GS4071. Harris BA. Studies on induced influenza in man, II: 4. Colman PM, Varghese JN, Laver WG. Structure of Antimicrob Agents Chemother. 1998;42:647-653. double-blind study designed to assess the prophylac- the catalytic and antigenic sites in influenza virus neur- 18. Sidwell RW, Huffman JH, Barnard DL, et al. In- tic efficacy of an analogue of amantadine hydrochlo- aminidase. Nature. 1983;303:41-44. hibition of influenza virus infections in mice by GS4104, ride. JAMA. 1968;203:1095-1099. 5. Colman PM. Influenza virus neuraminidase: struc- an orally effective influenza virus neuraminidase in- 31. Hayden FG, Zlydnikov DM, Iljenko VI, Padolka YV. ture, antibodies, and inhibitors. Protein Sci. 1994;3: hibitor. Antiviral Res. 1998;37:107-120. Comparative therapeutic effect of aerosolized and oral 1687-1696. 19. Kim CU, Bischofberger N, Williams MA, Lew W, rimantadine HCl in experimental human influenza A vi- 6. Varghese JN, McKimm-Breschkin JL, Caldwell JB, Merson J, Sweet C. Efficacy of GS4104 in ferrets infected rus infection. Antiviral Res. 1982;2:147-153. Kortt AA, Colman PM. The structure of the complex with influenza A virus. Antiviral Res. 1997;34:A74. 32. Hayden FG, Monto AS. Oral rimantadine hydro- between influenza virus neuraminidase and sialic acid, 20. Eisenberg G, Bidgood A, Lynch G, Lee WA, Cundy chloride therapy of influenza A virus H3N2 subtype the viral receptor. Proteins. 1992;14:327-332. K. Penetration of GS4071: a novel influenza neuramini- infection in adults. Antimicrob Agents Chemother. 7. von Itzstein M, Wu WY, Kok GB, et al. Rational dase inhibitor into rat bronchoalveolar lining fluid fol- 1986;29:339-341. design of potent sialidase-based inhibitors of influ- lowing oral administration of the prodrug GS4104. An- 33. Hayden FG, Sperber SJ, Belshe RB, Clover RD, Hay enza virus replication. Nature. 1993;363:418-423. timicrob Agents Chemother. 1997;41:1949-1952. AJ, Pyke S. Recovery of drug-resistant influenza A vi- 8. Ryan DM, Ticehurst J, Dempsey MH, Penn CR. 21. Wood ND, Aitken M, Sharp S, Evison H. Toler- rus during therapeutic use of rimantadine. Antimi- Inhibition of influenza virus replication in mice by ability and pharmacokinetics of the influenza neur- crob Agents Chemother. 1991;35:1741-1747. GG167 (4-guanidino-2,4-dideoxy-2,3-dehydro-N- aminidase inhibitor Ro-64-0802 (GS4071) following 34. Togo Y, Hornick RB, Felitti VJ, et al. Evaluation acetylneuraminic acid) is consistent with extracellular oral administration of the prodrug Ro-64-0796 of therapeutic efficacy of amantadine in patients with activity of viral neuraminidase (sialidase). Antimicrob (GS4104) to healthy male volunteers. In: Abstracts of naturally occurring A2 influenza. JAMA. 1970;211: Agents Chemother. 1994;38:2270-2275. the 37th Interscience Conference on Antimicrobial 1149-1156. 9. Ryan DM, Ticehurst J, Dempsey MH. GG167 (4- Agents and Chemotherapy; September 28-October 35. VanVoris LP, Betts RF, Hayden FG, Christmas WA, guanidino-2,4-dideoxy-2,3-dehydro-N-acetylneur- 1, 1997; Toronto, Ontario. Abstract A-123. Douglas RGJ. Successful treatment of naturally oc- aminic acid) is a potent inhibitor of influenza virus in 22. Hayden FG, Tunkel AR, Treanor JJ, Betts RF, Aller- curring influenza A/USSR/77 H1N1. JAMA. 1981; ferrets. Antimicrob Agents Chemother. 1995;39:2583- heiligen S, Harris J. Oral LY217896 for prevention of 245:1128-1131. 2584. experimental influenza A virus infection and illness in 36. Douglas RGJ. Prophylaxis and treatment of in- 10. Hayden FG, Osterhaus ADME, Treanor JJ, et al. humans. Antimicrob Agents Chemother. 1994;38: fluenza. N Engl J Med. 1990;322:443-450. Efficacy and safety of the neuraminidase inhibitor zana- 1178-1181. 37. Hayden FG, Atmar RL, Schilling M, et al. Safety and mivir in the treatment of influenza virus infections. 23. Walker JB, Hussey EK, Treanor JJ, Montalvo A, efficacy of oral GS4104 in long-term prophylaxis of natu- N Engl J Med. 1997;337:874-879. Hayden FG. Effects of the neuraminidase inhibitor zana- ral influenza. In: Final Program, Abstracts and Exhibits 11. MIST Study Group. Randomized trial of efficacy and mivir on otologic manifestations of experimental hu- Addendum: 38th Annual Interscience Conference on safety of inhaled zanamivir in treatment of influenza A man influenza. J Infect Dis. 1997;176:1417-1422. Antimicrobial Agents and Chemotherapy; September and B virus infections. Lancet. 1998;352:1877-1881. 24. Hayden FG, Fritz RS, Lobo M, Alvord G, Strober 24-27, 1998; San Diego, Calif. Abstract LB-6. 12. Cass LMR, Efthymiopoubs C, Bye A. Pharmaco- W, Straus SE. Local and systemic cytokine responses 38. Treanor JJ, Vrooman PS, Hayden FG, Kinnersley kinetics of zanomivir after intravenous, oral inhaled, during experimental human influenza A virus infec- N, Ward P, Mills RG. Efficacy of oral GS4104 in treat- or intranasal administration to healthy volunteers. Clin tion. J Clin Invest. 1998;101:643-649. ing acute influenza. In: Final Program, Abstracts and Pharmacokinet. 1999;36(suppl):1-11. 25. Santer TJ, Snell MK. Small-sample confidence in- Exhibits Addendum: 38th Annual Interscience Confer- ϫ 13. Cass LMR, Brown J, Pickford M, et al. Pharma- tervals for P1-P2 and P 1/P2 in 2 2 contingency tables. ence on Antimicrobial Agents and Chemotherapy; Sep- coscintigraphic evaluation of lung deposition of in- J Am Stat Assoc. 1980;75:386-394. tember 24-27, 1998; San Diego, Calif. Abstract LB-4. haled zanomivir in healthy volunteers. Clin Pharma- 26. Sears SD, Clements ML. Protective efficacy of low- 39. Aoki FY, Osterhaus AD, Rimmelzwaan GF, Kin- cokinet. 1999;36(suppl):21-31. dose amantadine in adults challenged with wild-type nersley N, Ward P. Oral GS4104 successfully reduces 14. Kim CU, Lew W, Williams MA, et al. Influenza influenza A virus. Antimicrob Agents Chemother. 1987; duration and severity of naturally acquired influenza. neuraminidase inhibitors possessing a novel hydro- 31:1470-1473. In: Final Program, Abstracts and Exhibits Addendum: phobic interaction in the enzyme active site: design, 27. Smorodintsev AA, Zlydnikov DM, Kiseleva AM, 38th Annual Interscience Conference on Antimicro- synthesis, and structural analysis of carbocyclic Romanov JA, Kazantsev AP, Rumovsky VI. Evalua- bial Agents and Chemotherapy; September 24-27, sialic acid analogues with potent anti-influenza tion of amantadine in artificially induced A2 and B 1998; San Diego, Calif. Abstract LB-5.

Downloaded From: https://jamanetwork.com/ on 09/26/2021