Among the highlights of the International AIDS conference in Vienna have been the results of the CAPRISA 004 trial, a study evaluating the efficacy and safety of 1% tenofovir gel for the prevention of HIV infection in women. Currently condoms provide the sole physical barrier for HIV prevention among women, however the use of male condoms requires cooperation by sexual partners and access to female condoms is limited in many resource-limited settings.
Quarraisha Abdool Karim presented the results of the CAPRISA study conducted in Vulindela and eThekwini South Africa, where HIV prevalence among women in ranges from 11-51%. This was a proof of concept, double-blinded, randomized, placebo-controlled trial, in which 889 women were enrolled and randomized to either tenofovir or placebo gel, used 12 hours before and 12 hours after sex.
The results revealed HIV incidence 5.6 per 100 woman-years in the tenofovir group and 9.1 per 100 woman-years in the placebo group, or a 39% reduction in the tenofovir gel group (IRR 0.61, 95% CI: 0.4-0.94). Retention rates in the trial were high (94.8%). Adherence rates to gel were directly related to efficacy, with high adherers (>80% gel adherence) showing 54% reduction, and low adherers (<50% gel adherence) showing only 28% reduction in risk.
The impact of tenofovir gel on HSV-2 infections was also examined in this study. Salim Karim discussed the experiences of 434 HSV-2 negative women monitored for HSV-2 acquisition (208 assigned to tenofovir arm and 226 to placebo arm). HSV-2 incidence in the tenofovir arm was 9.9 per 100 women-years and 20.2 per 100 woman-years in the placebo group, equivalent to a 51% reduction against HSV-2 by tenofovir gel (IRR 0.49; 95% CI 0.30-0.78).
No tenofovir resistance was noted in women infected while using tenofovir gel. The tenofovir gel was well tolerated. There was no increase in overall rate of adverse effects, although women had a small increase in diarrhea (17% vs. 11%, p=0.015). No hepatotoxicity was noted in women with concurrent hepatitis B coinfection.
Despite the promising results of this study, the results will need to be confirmed to provide definitive evidence for licensure and public availability of the gel.
References:
Sokal D, Karim Q, Omar Z, Grobler A, Yende N, Sibeko S, Frohlich J, Mansoor L, Abdool Karim S. Effectiveness of 1% tenofovir vaginal microbicide gel in South African women: results of the CAPRISA 004 trial. Presented by Quarraisha Abdool Karim, July 20, at the XVIII International AIDS Conference, Vienna, Austria. Oral Abstract TUSS0502.
Sokal D, Karim Q, Omar Z, Grobler A, Yende N, Sibeko S, Frohlich J, Mansoor L, Abdool Karim S. Safety of 1% tenofovir vaginal microbicide gel in South African women: results of the CAPRISA 004 trial. Presented by Salim Abdool Karim, July 20, at the XVIII International AIDS Conference, Vienna, Austria. Oral Abstract TUSS0504.
07/20/10
PRN Reports From AIDS 2010: Tenofovir Gel Safely Decreases HIV Transmission to South African Women
Source: Reporting from Vienna, Austria for PRN News: Anita Radix MD, MPH and Susan Weiss FNP, AAHIVS