Abdool Karim SS, Richardson BA, Ramjee G, Hoffman IF, Chirenje ZM, Taha T, Kapina M, Maslankowski L, Coletti A, Profy A, Moench TR, Piwowar-Manning E, Masse B, Hillier S, Soto-Torres L: HIV Prevention Trials Network (HPTN) 035 Study Team
To determine the safety and effectiveness of BufferGel and 0.5% PRO2000 microbicide gels for the prevention of male-to-female HIV transmission.
Phase II/IIb, randomized, placebo-controlled trial with three double-blinded gel arms and an open-label no gel arm.
Study participants from Malawi, South Africa, Zambia, Zimbabwe, and the USA were instructed to apply study gel up to 1 h before each sex act and safety, sexual behavior, pregnancy, gel adherence, acceptability, and HIV serostatus were assessed during follow-up.
The 3101 enrolled women were followed for an average of 20.4 months with 93.6% retention and 81.1% self-reported geladherence. Adverse event rates were similar in all study arms. HIV incidence rates in the 0.5% PRO2000 gel, BufferGel, placebo gel, and nogel arms were 2.70, 4.14, 3.91, and 4.02 per 100 women-years, respectively. HIV incidence in the 0.5% PRO2000 gel arm was lower than the placebo gel arm (hazard ratio = 0.7, P = 0.10) and the no gel arm (hazard ratio = 0.67, P = 0.06). HIV incidence rates were similar in theBufferGel and both placebo gel (hazard ratio = 1.10, P = 0.63) and no gel control arms (hazard ratio = 1.05, P = 0.78). HIV incidence was similar in the placebo gel and no gel arms (hazard ratio = 0.97, P = 0.89).
The 0.5% PRO2000 gel demonstrated a modest 30% reduction in HIV acquisition in women. However, these results were not statistically significant and subsequent findings from the Microbicide Development Programme (MDP) 301 trial have confirmed that 0.5%PRO2000 gel has little or no protective effect. BufferGel did not alter the risk of HIV infection. Both products were well tolerated.