Gel Not Shown to Reduce HIV-1 Incidence in Women
PRO2000 microbicide at two concentrations not effective against vaginally-acquired infection
MONDAY, Sept. 20 (HealthDay News) -- PRO2000 microbicide gel is not efficacious against vaginal HIV-1 transmission, according to research published online Sept. 20 in The Lancet.
Sheena McCormack, of the MRC Clinical Trials Unit in London, and colleagues analyzed data from 8,859 HIV-1-free women in Tanzania, South Africa, Uganda, and Zambia. Participants were randomized to receive 2- or 0.5-percent PRO2000 or placebo gel for 52 weeks to apply before intercourse.
The use of the 2-percent gel was discontinued due to low probability of benefit. The researchers found that HIV-1 incidence at discontinuation was 4.7 and 3.9 per 100 woman-years for the 2- and 0.5-percent formulations, respectively, compared to 3.9 per 100 woman-years for placebo. The average reported gel use at the last sex act was 89 percent.
"This finding is disappointing in view of the promising results from the HPTN 035 trial of PRO2000 that found a nonsignificant 30 percent reduction in HIV-1 incidence compared with placebo gel in the intention-to-treat analysis. Despite the success of the trial in terms of the investigators' commitment to community partnerships, their incorporation of mixed methods, and their adherence to the highest international scientific standards, McCormack and colleagues' results will certainly indicate the end of the road for PRO2000 as a potential HIV-prevention tool for women," write the authors of an accompanying commentary.
A co-author is employed by Endo Pharmaceuticals Solutions, the owner of PRO2000, which provided funding for the study.