NEW YORK, June 12, 2013 /PRNewswire-USNewswire/ -- Results from the Bangkok Tenofovir Study published online today in The Lancet provide additional evidence that daily oral tenofovir-based pre-exposure prophylaxis (PrEP) reduces HIV infection risk when taken consistently. The results from the study—the first conducted among people who inject drugs—are consistent with previous studies among men and women primarily at risk of acquiring HIV through sex. They provide additional support for moving forward to ensure that people who can benefit from PrEP have access to it.
"These results underscore what we've learned in a range of studies—daily tenofovir-based PrEP works when you take it," said Mitchell Warren, AVAC executive director. "Although there is more to learn about how this or other PrEP strategies work in men and women who inject drugs, this study offers the first indication that oral PrEP may reduce the risk of HIV infection via needle exposure. Comprehensive harm reduction, along with human rights protections, are the fundamental HIV prevention tools for injecting drug users. We need to continue to roll out proven prevention and find out more about how this oral PrEP strategy might work in a group that is at very high risk for HIV infection and has too often been ignored."
"We now need to get serious about making PrEP available to those who can benefit. More than two and a half years after the first positive results from a PrEP trial, little has been done to answer critical questions about the best ways to roll out daily oral PrEP to key populations worldwide. Within the next year, a comprehensive package of demonstration projects should be planned, funded and launched in countries around the world," Warren said.
Data from previous oral PrEP studies showed varying levels of effectiveness of tenofovir-based prevention for heterosexual men and women, and for men and transgender women who have sex with men. In July 2012, the US Food and Drug Administration (FDA) approved daily oral TDF/FTC (marketed as Truvada) for HIV prevention for all adults at risk of HIV from sexual transmission based on data from several PrEP trials that evaluated TDF/FTC for PrEP. Only one other PrEP study—Partners PrEP, which enrolled serodiscordant couples—evaluated daily oral tenofovir disoproxyl fumarate (TDF, marketed as Viread), as well TDF/FTC. It will be critical to examine the cost and feasibility of both daily TDF and TDF/FTC in light of these new data.
The Bangkok Tenofovir Study, which was conducted by the US Centers for Disease Control and Prevention (CDC), the Bangkok Metropolitan Association and the Thailand Ministry of Public Health, found that a daily dose of the drug tenofovir reduced the risk of HIV infection by 49 percent overall and at a higher rate (up to 74 percent) among trial participants who had detectable tenofovir in their blood, an indication that they were taking the drug consistently. The study, which began in 2005, enrolled more than 2,400 men and women who were part of a drug treatment program run by the city of Bangkok.
The trial team states the conclusion that the HIV infections that occurred were primarily the result of injection drug use, rather than sexual exposure. The team also reports consistent decreases in reported risk behaviors including injection drug use, needle sharing and unprotected sex in both study arms; also of note, the preventive benefit was only observed after the first three years of follow-up.
"People who use drugs also have sex, and there is no way of distinguishing between infection acquired via sex versus drug use. This is one reason why this PrEP strategy cannot be viewed as a replacement for proven prevention such as syringe exchange and drug substitution programs that specifically reduce risk of HIV via drug use. All countries need to offer these services without criminalizing, stigmatizing or infringing on the rights of those who need them," Warren said. "However, this is the first trial to provide evidence for a prevention option that could protect against HIV infection through both sexual contact and injecting drug use—and this is an exciting finding that must be followed up. PrEP could be a powerful additional tool for some people who inject drugs," Warren added.
CDC's new interim guidelines also released Wednesday include important guidance for how PrEP can best be used to help people who inject drugs protect themselves. Consolidated US Public Health Service Guidelines on PrEP use for all risk groups, which will include more detailed guidance on PrEP use for injecting drug users, are expected to be released later this year.
"We commend the CDC for acting quickly to put these interim guidelines in place to help individuals and their health care providers make informed decisions about PrEP use in the context of comprehensive HIV prevention. PrEP is not a silver bullet or a simple solution, but it is an option that can be life-saving for some individuals," Warren added.
"PrEP using tenofovir-based drugs is a niche product that cannot and will not replace other options that are part of combination prevention. Yet it is an intervention with the real possibility of preventing infections, especially where other prevention options aren't enough," Warren said.
"Now, policy makers, regulators, advocates, WHO, UNAIDS and Gilead Sciences—the manufacturer of both TDF and TDF/FTC—must work together to determine how best to move forward to ensure that PrEP is included where appropriate in comprehensive harm reduction programs for people who inject drugs. PrEP must complement, not replace, harm reduction programs everywhere, and especially in countries and communities with significant HIV epidemics driven by injecting drugs," Warren added.
"AVAC recognizes the altruism and commitment of the more than 2,400 trial volunteers who made this effort possible," Warren said. "These volunteers and their communities have made an inestimable contribution to HIV prevention research and to the eventual development of new ways for men and women to protect themselves from HIV."
About AVAC: Founded in 1995, AVAC is a non-profit organization that uses education, policy analysis, advocacy and a network of global collaborations to accelerate the ethical development and global delivery of AIDS vaccines, male circumcision, microbicides, PrEP and other emerging HIV prevention options as part of a comprehensive response to the pandemic.