HIV Gel Offers No Protection against AIDS
A tenofovir-based HIV gel used in protection against AIDS was recently removed from a study aimed at developing an antiviral resistance drug treatment in sub-Saharan Africa. The HIV gel initially showed significant results in HIV prevention in previous studies, but now has been determined by a monitoring board of review to be ineffective towards preventing the transmission of HIV in its current gel form.
In South Africa, young women are five times more likely to become infected with HIV than their male counterparts. Overall, women make up sixty percent of the adults who test positive for HIV in sub-Saharan Africa, with twenty-six percent of all new cases occurring in females between the ages of 15 and 24.
Due to the dire need of HIV prevention where it has reached epidemic proportions in Africa, researchers are developing anti-retroviral (ARV) medications to be used prophylactically to combat the problem. Unprotected sex between heterosexual partners accounts for the majority of the HIV epidemic. Preventive measures such as condom use have resulted in some rate decrease with infections; however, “condom negotiation” between women and their male partners often results in unprotected sex. Therefore, a need for an easily taken ARV oral pill or easily applied vaginal and anal gel containing an ARV medication has been the focus of recent research.
One such ARV medication is a tenofovir-containing gel that raised hopes during an announcement at the 2010 18th International AIDS Conference in Vienna. Researchers at the conference proclaimed that the results of their CAPRISA 004 clinical trial showed that an ARV microbicide gel containing tenofovir has an overall effective rate of 39 percent in protecting women against HIV infection.
The result of the announcement was a series of clinical trials this year at multiple sites in Uganda, South Africa and Zimbabwe involving over 5 thousand sexually active women who are HIV negative. The trials are part of the Vaginal and Oral Interventions to Control the Epidemic (VOICE) program conducted by the Microbicide Trials Network and overseen by The National Institutes of Health (NIH).
In a blinded study involving the tenofovir gel, 5 groups of approximately 1,000 women each were provided separately with tenofovir gel, a placebo gel, two oral tenofovir tablets or a placebo tablet. The controls were necessary to determine whether any of the tenofovir treatments demonstrated a protective effect, and if so, how much.
During the study, however, an independent Data and Safety Monitoring Board found that while taking the tenofovir gel was not hazardous to health, it was not any more effective than the control placebo in preventing HIV infection. The HIV incidence rates between the placebo gel and the tenofovir gel were 6.1 percent and 6.0 percent respectively, meaning that six out of every 100 women tested had become infected with HIV.
The recommendation by the board of review was to discontinue the gel portion of the study—a decision subsequently backed by the National Institute of Allergy and Infectious Diseases (NIAID). The tablet portions of the study, however, are not affected by the recommendation and are continuing in progress.
The reason for the discrepancies in results between the tenofovir gel reported at the 2010 18th International AIDS Conference in Vienna and the recent sub-Saharan tenofovir gel study is not currently available pending comparative analysis of data. While the discontinuation of the gel study is a setback, researchers believe that tenofovir still offers promise as an eventual effective therapeutic against HIV infection and AIDS.
Other modalities of treatment for South African are in the works in a study slated for next year testing the effectiveness of a vaginal ring containing the ARV dapivirine.
Reference: Microbicide Trials Network