Truvada, which is a fixed drug combination containing the ARVs emtricitabine (FTC) and tenofovir (TDF), was given orally to 2 499 HIV-negative gay men and transgender women who have sex with men, between June 2007 and May this year.
The study, reported in the New England Journal of Medicine, is evidence that this HIV prevention method, called pre-exposure prophylaxis or PrEP, reduces HIV infection risk in people and it provides important clues as to how ARVs might be used for prevention in HIV-negative people at high risk for HIV infection .
Briefing a select group of media before the official release of the results in Cape Town yesterday (subs Tuesday) a principal investigator responsible for the Cape Town site and University of Cape Town professor Linda-Gail Bekker revealed that the iPrEx oral PrEP study had found an average HIV reduction rate of 43,8 percent.
The study was conducted at 11 sites including in Cape Town, the United States, Peru, Brazil, Ecuador and Thailand.
At the end of the three year trial, 36 HIV infections were recorded among the 1 251 study participants who received Truvada and 64 of the 1 248 study participants who received a placebo pill. The average reduction in HIV infection risk of 43.8% includes all study participants ‘ even those who did not take the daily pill consistently.
Participants who reported taking their pills correctly and consistently the majority of the time had significantly lower risk of HIV infection compared to those who reported taking the pills less frequently.
Bekker said that in cases where participants reported taking the drug half of the time the reduction in HIV infection was just over 50% while in those who took it 90% of the time, the reduction was over 70%.
Throughout the study participants received robust health care including pre and post HIV counselling, comprehensive prevention messaging and condoms with lubricants. Participants were tested monthly to identify those who had seroconverted during the study. Their partners received sexually transmitted infection (STI) treatment when needed. Those who reported being exposed to HIV were given post exposure prophylaxis.
An important source of additional information will be a follow-up trial, which will begin in early 2011 and be open to all participants from the original iPrEx trial. All HIV-negative participants who choose to join this open-label trial will receive the active Truvada pill along with an HIV prevention package and will be counseled on daily use of the drug. However, monitoring and HIV testing will be less frequent, with the goal of learning about PrEP safety and effectiveness in a ‘real world’ context.
Almost half of the participants were younger than 24 and the majority reported having a secondary education and a risky sexual life coupled with high levels of alcohol use. At screening at least 13 percent of the 2 499 participants were found to have syphilis and 37 percent had HSV2 (Herpes Simplex Virus) ‘ both common STIs. Most were given a Hepatitis B vaccine.
Bekker said study was important to South Africa and the African Continent. ‘It is unlikely that we will be able to treat our way out of this epidemic. We are going to have to find innovative, affordable and practical ways to stop the ongoing transmission of HIV. To do this effectively we will need a variety of proven strategies that can be offered to individuals from many diverse sexual orientations, practices and risk profiles to enable them to protect themselves in a sustainable and meaningful way’ she said.
The Gilead manufactured drug which is registered in South Africa, but not for this purpose, currently costs R369 for a month’s supply of 30 pills.
Mitchell Warren, Executive Director of AVAC, involved in advocacy around new prevention methods, said after many years of disappointing results from biomedical prevention trials, iPrEx and the Caprisa 004 trial on tenofovir gel, marked the beginning of a new era of HIV prevention.
CAPRISA’s Director Dr Salim S Abdool Karim said the iPrEx study result was good news for Africa, ‘since unprotected anal sex is common from Cape to Cairo’.
The prevalence of HIV in men who have sex with men is 6.2% in Cairo while anal sex in the last 3 months was reported by 14% of 2593 Cape Town men – about a third of these sex acts were not protected by condoms.
CAPRISA, based at the University of KwaZulu-Natal, is participating in the VOICE (Vaginal and Oral interventions to Control the Epidemic) study which is assessing whether the tablet and gel forms of tenofovir can prevent HIV acquisition in women. The results of the VOICE study are expected in about two years from now.