iPrEx Clinical Trial Demonstrates 44 Percent Protection Against HIV
Mounting Evidence of the Power of ARVs to Prevent HIV Transmission
Statement from Dr. Zeda Rosenberg, CEO, International Partnership for Microbicides
SILVER SPRING, Md. (November 23, 2010) — In a significant research advance, results from the iPrEx (Pre-Exposure Prophylaxis Initiative) clinical trial published today in The New England Journal of Medicine show that taking an oral antiretroviral (ARV) medication (Truvada®) once a day along with comprehensive HIV prevention services led to a 44 percent reduced risk of becoming infected with HIV-1 in the clinical trial population. The iPrEx results provide the first proof-of-concept that pre-exposure prophylaxis (PrEP) could be a key additional method to prevent HIV infection, and IPM congratulates the iPrEx team and study volunteers for their important contributions to HIV prevention research.
The iPrEx data announced today add to milestone findings presented in July from the CAPRISA 004 trial showing that an ARV-based vaginal microbicide gel reduces the risk of HIV transmission in women. A similarity between these two trials is that tenofovir, one of the ARV drugs in Truvada®, was the active ingredient shown to reduce the risk of HIV infection in women in the CAPRISA 004 trial when formulated as a vaginal gel.
Taken together, these two trials provide mounting evidence of the power of ARVs to prevent HIV transmission. Success of this approach has already been achieved by administering ARV drugs to HIV-infected mothers during childbirth to reduce their infant’s chance of contracting HIV.
The iPrEx study was a double-blind, placebo-controlled, Phase III clinical trial, sponsored by the U.S. National Institutes of Health with co-funding from the Bill & Melinda Gates Foundation and study medication donated by Gilead Sciences, Inc. The trial enrolled 2,499 HIV-negative, male volunteers and took place at 11 research sites in Brazil, Ecuador, Peru, South Africa, Thailand and the United States.
The iPrEx trial, which began in June 2007, showed that daily use of a single, oral tablet of the ARV medicine Truvada® is safe and effective in reducing HIV infection among men who have sex with men, when combined with monthly HIV testing and ongoing monitoring for side effects, safer sex counseling, condom distribution and sexually transmitted infection (STI) management. Truvada® is an FDA-approved HIV treatment that contains two ARV drugs in one tablet: tenofovir disoproxil fumarate (TDF-300 mg) and emtricitabine (FTC-200 mg). There were 64 HIV infections recorded among the 1,248 participants who received a placebo pill, while 36 HIV infections were recorded among those who received the study drug. Researchers caution that there are risks for anyone taking PrEP, including the potential to develop HIV drug resistance. The only way to minimize these risks is through ongoing monitoring and testing. The iPrEx study found no evidence that the study drug taken orally provided protection against any other sexually transmitted infections including herpes simplex virus 2 (HSV-2).
Adherence during the iPrEx study was measured by pill counts, bottle counts and self-reporting. Greater protection was found among those who reported taking the pill more regularly. Among participants who used the tablet on 50 percent or more of days, the risk of HIV infection fell by 50 percent; among those who used the pill on 90 percent or more of days, infection risk declined by over 72 percent.
Adapting different forms of ARVs to protect healthy adults from becoming infected with HIV has great potential to transform the global response to the HIV/AIDS epidemic. A number of additional PrEP efficacy trials are ongoing testing oral tenofovir or Truvada® in diverse populations including heterosexual men and women. Numerous questions remain to be addressed in the PrEP field, for instance, the optimal frequency of HIV testing to minimize the potential to develop viral resistance for those who become HIV infected while using PrEP.
The results of both CAPRISA 004 and iPrEx provide growing evidence that ARV-based microbicides and oral PrEP, combined with current HIV-prevention options, can help stem the tide of the HIV/AIDS epidemic. Other HIV-prevention products being developed include ARV-containing vaginal rings and injections that may provide protection for a month or longer. A long-acting product could lead to greater adherence (correct and consistent use of the product), and hence improved effectiveness of the product in preventing HIV.
The spread of the HIV epidemic continues to outpace the world’s response to it, and research must continue as quickly as possible to provide the world with new HIV prevention tools. The hard work and dedication of the iPrEx team and trial participants has led to a second successful proof-of-concept this year for an ARV-based HIV-prevention product. We must not falter at this important time in history when science shows us that, with sufficient resolve, we can begin to control and potentially reverse the HIV epidemic.
UPDATE: iPrEx trial released new data analyses at the 18th Conference on Retroviruses and Opportunistic Infections on March 1, 2011, in Boston showing “durable benefit of pre-exposure prophylaxis at 144 weeks.”
About IPM: IPM is a nonprofit product development partnership dedicated to developing new HIV prevention technologies and making them available to women in developing countries. IPM has offices in the United States, South Africa and Belgium. To learn more, please visit www.IPMglobal.org.