Reducing the Incidence of Nevirapine Resistance Mutations in Pregnant HIV Infected Women Who Receive Anti-HIV Drugs Prior to and After Giving Birth

Phase II Study of the Pharmacokinetics of Nevirapine and the Incidence of Nevirapine Resistance Mutations in HIV-Infected Women Receiving a Single Intrapartum Dose of Nevirapine With the Concomitant Administration of Zidovudine/Didanosine or Zidovudine/Didanosine/Lopinavir/Ritonavir

The purpose of this study is to determine which of 3 different anti-HIV drug regimens given to HIV infected pregnant women during and after their pregnancies is most effective in reducing the incidence of nevirapine (NVP) resistance mutations. Blood levels of NVP and lopinavir/ritonavir (LPV/r) will also be studied.

Study hypothesis: NVP resistance following single-dose NVP can be prevented with the concomitant administration of additional antiretroviral therapy (ART).

A single dose of nevirapine (SD-NVP) given to an HIV infected pregnant woman in labor followed by a single dose to her infant had been shown to be a simple and effective means of reducing mother-to-child transmission (MTCT) of HIV among women who had not received antiretroviral (ART) during pregnancy. However, development of NVP and other nonnucleoside reverse transcriptase inhibitor (NNRTI)-resistant virus was a concern. An optimal ART regimen that can prevent selection of resistant virus while efficiently preventing MTCT was needed. This study evaluated 3 different ART strategies for preventing the development of NVP resistance in HIV infected pregnant women and compared the incidence of NVP resistance mutations postpartum observed with each regimen to the incidence among historical controls. NVP and LPV/r pharmacokinetics (PK) were also evaluated in this study.

Participants were randomly assigned to one of three study arms. All study participants received a single dose of oral NVP at the onset of labor and, oral zidovudine (ZDV) at the onset of labor, and every three hours during labor. Arm A: (LPV/r x 7d) participants received enteric-coated didanosine (ddI) and LPV/r orally twice daily beginning at the onset of labor and continuing through 7 days postpartum; oral ZDV was also taken twice daily for 7 days postpartum. Arm B: (no LPV/r) participants received enteric-coated ddI beginning at the onset of labor and continued through 30 days postpartum; oral ZDV was also taken twice daily for 30 days postpartum. Arm C : (LPV/r x 30d) participants received enteric-coated ddI and LPV/r orally twice daily beginning at the onset of labor and continued through 30 days postpartum; oral ZDV was also taken twice daily for 30 days postpartum.

All women were followed for at least 24 weeks postpartum. Women with resistance mutations identified within 8 weeks postpartum were to be followed until 72 weeks postpartum to evaluate the persistence of the mutations. All infants were followed until at least 12 weeks of age. HIV-infected infants were to be followed until 24 weeks of age. There were 11 study visits for women at day 10, 21, and 30 and week 5, 6, 8, 12, 24, 36, 48, and 72. Medical history assessment, a physical exam, and blood collection occurred at all visits. Blood collection for PK studies occurred at Days 10, 21, and 30. All women were asked to complete an adherence questionnaire at Day 10; women assigned to Arms A : LPV/r x 7d and B: no LPV/r were also asked to complete an adherence questionnaire at Day 30. There were 6 study visits for infants at birth - 48 hours, day 21, week 5, 12, 16 and 24. Medical history assessment and a physical exam occurred at most visits; blood collection occurred at all visits.

Data and specimens for the historical control comparison group were obtained from the PHPT-2 trial*, in which five of the P1032 study sites had participated between 2001 and 2003. PHPT-2 was a study of the efficacy of SD-NVP to prevent MTCT among women who received ZDV after 27 weeks gestation but no postpartum ART. Criteria for inclusion in the historical comparison group included receipt of SD-NVP, a CD4 count of more than 250 cells per cubic millimeter within 30 days of screening or entry, and the availability of plasma samples at 10 days or 6 weeks post-partum.

* Lallement M, Jourdain G, Le Coeur S, et al. Single-dose perinatal nevirapine plus standard zidovudine to prevent mother-to-child transmission of HIV-1 in Thailand. N Engl J Med 2004; 351:217-28.

Inclusion Criteria for Mothers:

• HIV infected
• Pregnant with a viable fetus
• Between 28 and 38 weeks of pregnancy
• CD4 count greater than 250 cells/mm3 within 30 days prior to study entry
• Able to receive oral ART during labor
• Willing to use acceptable forms of contraception while on study treatment
• Able to provide written informed consent

Exclusion Criteria for Mothers:

• Known allergy or hypersensitivity to ddI, LPV, NVP, ritonavir (RTV), or ZDV
• Any ART other than ZDV during a previous pregnancy or the current pregnancy
• Certain medications
• Planning to receive additional ART during the first 8 weeks postpartum
• Planning to breastfeed
• Unlikely to comply with postpartum study requirements, in the opinion of the investigator
• Certain abnormal laboratory values within 30 days prior to study entry