LB7   Report of Results of PACTG 316: An International Phase III Trial of Standard Antiretroviral (ARV) Prophylaxis plus Nevirapine (NVP) for Prevention of Perinatal HIV Transmission

A. Dorenbaum¹for the PACTG 316 Study Team, Emeryville, CA

Background:PACTG 316 was a Phase III, randomized, double-blind, placebo-controlled trial to evaluate safety and efficacy of intrapartum/postpartum NVP added to standard ARV treatment for the prevention of maternal-fetal HIV transmission.

Methods:HIV-1 infected pregnant women receiving standard ARV therapy were randomized to receive 200 mg NVP or nevirapine placebo (PL) during active labor; infants received 2 mg/kg NVP or PL at age 48-72 Hrs. Women were followed for 6 weeks and infants for 6 months. Infants were tested for HIV DNA at day 1, and weeks 4-6, 12 and 24. Infants with 2 positive results were classified as "infected."

Results:1506 women were randomized (1052 PACTG; 287 France; 118 ECS; 31 Brazil; 18 Bahamas), between 5/97-6/00; 1,174 received study drug and had infants with known HIV status at the time of analysis. At entry median age was 28 yrs and CD4 count 431 Cell/ml; Maternal ethnicity was 58% Black, 18% Latino, 23% White. Antenatal ARV therapy was none in 1%; AZT alone, 23%; AZT/3TC, 28%; other combinations without or with protease inhibitors, 8% and 41% respectively. Delivery HIV RNA was below 400 copies/ml for 49% of women. Median gestational age at delivery was 38 wks; 34% had elective cesarean. No significant differences in birth weight, perinatal complications or maternal/infant toxicity were seen between study arms. HIV Perinatal transmission occurred in 17 infants (1.5%, 95% CI 1.0-2.7%): 9/594 (1.5%, 95% CI 0.7-2.8%) in NVP and 8/ 580 (1.4%, 95% CI 0.6-2.7%) in PL recipients, not statistically different. Nine of the 17infants were classified as antenatally infected (+ test at birth); 4 in NVP and 5 in PL recipients. There was a non-statistically significant trend for increased transmission risk in women with low CD4 count, high HIV RNA, vaginal forceps delivery and black race. No significant differences were observed between treatment arms in any subgroup.

Conclusions:Among HIV-infected women who receive prenatal care and who are treated with standard ARV prophylaxis (generally combination therapy), the risk of perinatal transmission is low (1.5%; 95% CI 1.0-2.7%). Administration of the 2-dose NVP prophylaxis regimen did not further reduce transmission in this setting.