Safety, Tolerance, and Efficacy of Atevirdine in Asymptomatic Human Immunodeficiency Virus-Infected Individuals

ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, Nov. 1996, p. 2664–2668 Vol. 40, No. 11 0066-4804/96/$04.0010 Copyright q 1996, American Society for Microbiology Safety, Tolerance, and Efficacy of Atevirdine in Asymptomatic Human Immunodeficiency Virus-Infected Individuals ANNE MIEKE M. BEEN-TIKTAK,1,2 IAN WILLIAMS,3 HENK M. VREHEN,1 JOHN RICHENS,3 3 2,4 5 2 DIANA ALDAM, ANTON M. VAN LOON, CLIVE LOVEDAY, CHARLES A. B. BOUCHER, 6 3 1 PENELOPE WARD, IAN V. D. WELLER, AND JAN C. C. BORLEFFS * Section of Infectious Diseases and Tissue Damage, Department of Internal Medicine,1 and Eijkman-Winkler Institute of Medical and Clinical Microbiology,2 University Hospital Utrecht, Utrecht, and Laboratory of Virology, National Institute of Public Health and Environmental Protection, Bilthoven,4 The Netherlands; Departments of Sexually Transmitted Diseases and Virology, Division of Pathology and Infectious Diseases, University College London Medical School,3 and Department of Retrovirology, Royal Free Hospital School of Medicine,5 London, United Kingdom; and Pharmacia & Upjohn Inc. Europe, Puurs, Belgium6 Received 25 March 1996/Returned for modification 15 May 1996/Accepted 27 August 1996 Atevirdine is a nonnucleoside reverse transcriptase inhibitor of human immunodeficiency virus type 1 (HIV-1). In this study we investigated the effect of atevirdine in asymptomatic antiretroviral naive HIV-infected patients with CD41 cell counts of between 200 and 750 cells per mm3. Patients were randomized to receive 600 mg of atevirdine (n 5 15) or a placebo (n 5 15) three times a day for 12 weeks. There was no statistically significant effect of atevirdine on viral loads (HIV p24 antigen and HIV-1 RNA levels by PCR) or CD41 cell counts. The data do not support the use of atevirdine as a monotherapy in the treatment of HIV-infected patients. Atevirdine is a bisheteroarylpiperazine (BHAP) that inhibits consent. The study was conducted in agreement with the dec- the reverse transcriptase (RT) of human immunodeficiency laration of Helsinki and its revisions (21). virus type 1 (HIV-1). The compound has a 50% inhibitory con- Male individuals aged over 18 years were eligible for the 1 centration (IC50) of approximately 1 mM (11, 15). BHAPs are study if they had (i) documented HIV-1 infection, (ii) a CD4 nonnucleoside RT inhibitors (NNRTIs), a structurally diverse cell count greater than 200 cells per mm3 but lower than 750 group of antiretroviral agents that have a similar mechanism of cells per mm3 or a CD41 cell count lower than 200 cells per RT inhibition by binding to a common region of RT near the mm3 if they had declined AZT therapy but wished to partici- nucleotide binding site (6, 12, 18). NNRTIs have exhibited syn- pate in the study, and (iii) normal liver function. Exclusion ergy with zidovudine (AZT) in inhibiting the replication of criteria were as follows: evidence of AIDS according to the AZT-resistant viral strains. By contrast, this combination had a 1987 case definition of the Centers for Disease Control (4), mostly additive effect when tested against AZT-susceptible hypersensitivity to piperazine-type drugs, any previous antiret- isolates (3, 15). The development of HIV-1 variants with re- roviral treatment, the abuse of hard drugs, and concomitant duced levels of sensitivity to BHAPs has been reported (13, 14, medications other than those for prophylaxis of Pneumocystis 19). Interestingly, however, virus strains resistant to BHAPs carinii pneumonia (cotrimoxazole, aerolized pentamidine, and appear to be more susceptible to other NNRTIs than the dapsone) and therapy for oral candidiasis (clotrimazole and corresponding wild-type strain (7). Furthermore, the concom- nystatin suspension) or herpes simplex infection (up to 1,000 itant use of two classes of RT inhibitors acting at different mg of acyclovir per day). enzymatic sites, i.e., NRTIs and NNRTIs, may prevent or delay At a screening visit up to 6 weeks prior to enrollment, the the development of viral resistance (20). A preceding escalat- patients’ medical histories were taken and physical examina- ing-single-dose study of atevirdine in HIV-infected individuals tions were performed. In addition, complete hematological showed that the compound was safe and well tolerated (1). In screening, blood chemistry, urinalysis (including screening for this report, the results of a phase Ib clinical trial with atevirdine the abuse of hard drugs), and electrocardiograms were per- are presented. This is the first study performed with asymp- formed. Baseline examinations of viral loads consisted of four tomatic HIV-infected individuals comparing the results of at- separate quantitative HIV-1 RNA determinations, according evirdine monotherapy and a placebo. to the method described by Semple et al. (17). The dynamic Study design. The study was a multicenter, double-blind, range of this immunocapture assay is 20 to 100,000 copies per placebo-controlled trial. Patients were randomized to receive ml. Since 1991 the assay has been used to analyze the dynamics either atevirdine or a matching placebo for 12 weeks. The of HIV and responses to antiretroviral therapy in several stud- dosage regimen, 600 mg three times a day, was based on the ies. It has been shown in longitudinal evaluations of drug pharmacokinetic data available from the AIDS Clinical Trials efficacies that the immunocapture assay exhibits patterns of Group 199 study (11). The protocol and the informed consent changing viral loads similar to those of commercial assays, such forms were approved by the investigational review board of as the Roche RT PCR, the Chiron bDNA, and the Organon each participating hospital. All patients gave written informed Teknika NASBA assays (10). CD41 cell counting was performed twice before entry and once at baseline by flow cytom- * Corresponding author. Mailing address: University Hospital Utrecht, etry (FACStar; Becton Dickinson, Mountain View, Calif.). The Department of Internal Medicine, Section of Infectious Diseases and safety parameters were repeated every week following institu- 1 Tissue Damage, P.O. Box 85500, 3508 GA Utrecht, The Netherlands. tion of drug therapy. CD4 cell counts, HIV p24 antigen levels Phone: 31 30 2506228/2509111. Fax: 31 30 2513828. (immune complex dissociated), and viral loads were measured 2664 VOL. 40, 1996 NOTES 2665 TABLE 1. Baseline characteristicsa of the patients in the two treatment groups Baseline level of patients in Parameter indicated treatment group Placebo Atevirdine CD41 cell count (cells/mm3) Mean 355 437 SE 36.23 42.36 HIV-1 RNA (log copies/ml) Mean 2.19 2.46 SE 0.71 0.90 HIV p24 antigen (pg/ml) Mean 363.90 249.43 SE 157.60 138.60 a The differences between the two study groups were not statistically significant for any of the three parameters. FIG. 1. Mean changes (and standard errors [SE]) in CD41 cell counts from the baseline during 12 weeks of treatment with atevirdine or the placebo and the subsequent 11 weeks of follow-up. at monthly intervals during the treatment period and follow- up. In order to measure possible changes in viral sensitivity to atevirdine during the study, peripheral blood mononuclear cells from the 20 Dutch patients were collected at baseline and of p24 antigen in sera was seen 3 weeks after the study start at weeks 11 and 23 and were stored frozen in liquid nitrogen. (Fig. 2). In the atevirdine-treated patients, the decline was Virus stocks were obtained by cocultivation of the stored sam- more sustained. However, in patients receiving the placebo, ples at the end of the study. These procedures were performed the mean p24 antigen level was already 77 pg/ml above the according to the AIDS Clinical Trials Group-Department of baseline level at week 11. This difference in response to treat- Defense consensus protocol (5, 9). Reduced sensitivity to at- ment was not statistically significant. evirdine was defined as a 10-fold increase in the IC or an The results of the quantitative HIV-1 RNA PCR with the 26 50 patients participating in the study from whom serum samples absolute IC50 of $10 mM (11). Trough serum atevirdine con- centrations at days 1 and 21 were determined by a high-per- were available for testing are shown in Fig. 3. For four patients, formance liquid chromatography procedure, as described ear- samples were not available either because of early withdrawal lier (8). Atevirdine was provided by The Upjohn Co. as 200 mg from the study or because of inadequate collection of speci- of nonmicronized powder in hand-filled hard gelatin capsules. mens. Of the patients taking atevirdine (Fig. 3, left side), one Placebo capsules of identical appearance contained 100 mg of showed a 2-log drop in the number of HIV-1 RNA copies per lactulose. milliliter. Unfortunately, no follow-up data are available be- The statistical analyses were performed according to the cause this patient developed an acute hepatitis and was with- on-treatment principle by using SAS software in a mainframe drawn from the study. One other patient showed a 1-log drop environment. All tests were two sided. Quantitatively mea- in response to treatment, but RNA levels returned to the sured variables were analyzed by the Student t test. For the baseline level at week 7. A third subject had a 0.5-log drop that analysis of CD41 cell and viral load responses, repeated-mea- was sustained until the end of the dosing phase of the study. In sures analysis of variance was used on each variable. For the CD41 cell count variable, a square root transformation was performed before repeated-measures analysis of variance analysis. A baseline value was defined as the mean of the screening and the day 0 assessments. Efficacy indicators were summa- rized in terms of absolute values and changes from baseline values.

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