New Developments

In 2009, results of the RV 144 trial conducted by several partners, including the NIH, the USMilitary HIV Research Program (USMHRP) and the Thai Ministry of Public Health, demonstrated modest protection by the ALVAC/gp120 candidate vaccine, but perhaps more importantly showed for the first time that an HIV vaccine was possible. The recent discovery of novel broadly neutralizing antibodies by a research consortium led by the International AIDS Vaccine Initiative (IAVI) and by the NIH Vaccine Research Center (VRC) have also generated new excitement. These recent scientific breakthroughs in the vaccine field have led to planning for new efficacy trials. One such trial would use a prime-boost candidate to attempt to improve upon the modest efficacy found in the RV 144 trial. Such a trial could cost from US$30 million to over US$100 million, depending upon trial size and the number of vaccine regimens being tested. In addition, the NIH and others are considering a passive antibody clinical trial as part of the development process for an antibody-based HIV vaccine.

CAPRISA 004, a Phase IIb clinical trial of tenofovir gel used as a coitally-dependent microbicide, reported results on July 19. 2010. Tenofovir is an ARV-based nucleotide reverse transcriptase inhibitor (NRTI). The study found tenofovir gel used in a dosing regimen timed before and after sex reduced HIV infections by 39 percent, a finding that is statistically significant. CAPRISA provided the first evidence that the use of the antiretroviral (ARV) drug tenofovir in the form of a vaginal gel can reduce the risk of HIV infection in women.  The “test of concept” trial tested the effectiveness of 1% tenofovir gel, used before and after sex, among urban and rural South African women at high risk of HIV via vaginal sex. The International Partnership for Microbicides’ (IPM) most clinically advanced candidate, a long-acting monthly dapivirine ring, continues to progress and is scheduled to enter Phase III evaluation in 2011. Dapivirine is an ARV-based non-nucleoside reverse transcriptase inhibitor (NNRTI). The evaluation would cost approximately US$ 90 million.

The iPrEx study, testing the safety and effectiveness of daily tenofovir/emtricitabine in preventing HIV transmission in 3000 HIV-negative men who have sex with men (MSM), is expecting to release results in early 2011. In addition, a study funded by the CDC testing daily dosage of tenofovir (CDC 4323) to prevent HIV infection in injection drug users in Bangkok, Thailand is expecting to release results by early 2011. These trials will provide the first effectiveness results for daily oral use of ARVs for HIV prevention.

A Thayer. "Prevention: Antiretroviral Agents May Help Avoid Infection." C&EN Chemical & Engineering News, Vol.86, No.38 (22 September 2008), p. 25.http://pubs.acs.org/cen/coverstory/86/8638cover1box.html

SSA Karim and C Baxter. “PRO 2000: next steps for microbicide development.” Future Virology, Vol.4, No.4 (July 2009), p.317-320.http://www.futuremedicine.com/doi/abs/10.2217/fvl.09.22