Phase I/II, Open-Label, Pharmacokinetic and Safety Study of a Novel Protease Inhibitor (BMS 232632, Atazanavir, ATV, Reyataz) in Combination Regimens in Antiretroviral Therapy (ART)-Naive and -Experienced HIV-Infected Infants, Children, and Adolescents

Advancements in HAART for HIV-infected children and adolescents are hindered by patient nonadherence. The availability of a powder formulation and the once-daily dosing schedule make ATV an attractive agent for improved adherence in pediatric treatment regimens. This study was designed to provide pharmacokinetic (PK) data to guide dosing recommendations for ATV, when given concurrently with or without low-dose RTV boost, in infants, children, and adolescents. During the study, the safety and tolerance of ATV (with or without low-dose RTV) were closely monitored, and virologic efficacy data were obtained.

There were two parts to this study. Step I took place in the United States and South Africa, and were further divided into two sets of groups, Parts A and B. Part A participants received ATV only and Part B participants received ATV with low-dose RTV boost. All participants received ATV once a day with 2 other antiretroviral drugs (not provided by the study). In Part B only, participants received ATV with a low dose of RTV. Participants were placed into 1 of 8 groups (Groups 1 to 4 for Part A; Groups 5 to 8 for Part B) with respect to age and study drug formulation. Participants in Groups 1 and 5 were infants between ages 3 months and 1 day (91 days) and 2 years (less than or exactly 730 days) and took ATV in powder form. Participants in Groups 2, 3, 6, and 7 were children between 2 years and 1 day (731 days) old and 13 years old. Groups 2 and 6 received ATV in powder form, while Groups 3 and 7 received the capsule form. Patients in Groups 4 and 8 were adolescents between 13 years and 1 day old and 21 years old (not including the 22nd birthday) and took ATV in capsule form. As of 01/02/2008 a new group, 5A was opened for enrollment. Participants in Group 5A were between 3 months and 6 months old and took ATV in powder form plus a low-dose RTV booster.

For each group, enrollment started with five participants per group. All participants were evaluated for PK and safety criteria, adjusting the dose of ATV until one was found that passes both sets of criteria. Then five additional participants were enrolled, with enrollment continuing for each group once all participants within that group meet the PK criteria. For groups receiving RTV (Groups 5 to 8), additional criteria must be met for each dose of ATV studied. In addition to the PK and safety evaluations, 24-hour post-dose concentrations (Cmin) were monitored in the first 10 participants enrolled for a dose of ATV before more participants were enrolled and studied at that same dose. Note that in Protocol Version 5.0, South African (S.A.) sites were allowed to enroll patients in study groups 3,4,5,6,7,8. As a result, the study design has been modified to further stratify study groups 3, 4, 5, 6, 7, 8 (at the final recommended dose), by country, i.e., U.S.A. versus S.A., such that 10 evaluable study subjects will be accrued in parallel to each study group-country cohort.

Clinic visits will be every 4 weeks through Week 48, then every 8 weeks until the last participant to enroll in the study has reached Week 96 of his/her treatment. If, after 56 weeks, a participant has a toxic reaction to a nucleoside/tide reverse transcriptase inhibitor (NRTI) in their medication regimen, the regimen may be changed to a different NRTI. At every visit, participants will undergo a complete medical history and physical exam, cardiac conduction evaluation, and urine and blood collection. Participants of childbearing age will have a pregnancy test performed at each visit.

Step II will only be open to South African subjects who are virologically responding to treatment when the last enrollee into either part of Step I (Part A or Part B) has completed 96 weeks of treatment (end of Step I) . All such participants will be given ATV in capsule form at the same dose they received at the end of Step I, as well as the other antiretrovirals they were receiving during Step I. Step II will continue until ATV is approved in South Africa and readily available by individual prescription, and participants will have a study visit every 12 weeks.