What we’re learning about new PrEP drugs and delivery methods at AIDS 2016

原文網址：What we’re learning about new PrEP drugs and delivery methods at AIDS 2016

What we’re learning about new PrEP drugs and delivery methods at AIDS 2016

July 21, 2016, by Emily Newman

BETA is reporting from the 21st International AIDS Conference this week in Durban, South Africa—bringing you the latest news, updates, and research on HIV treatment and prevention.

The drug maraviroc is safe and well-tolerated as pre-exposure prophylaxis for women

Maraviroc, a drug that is already on the market to treat HIV (brand name, Selzentry), is a CCR5 antagonist that concentrates in the genital tract and rectum, and selects for drug resistance uncommonly—making it a desirable product for PrEP, if it works.


The HPTN 069 study, which previously reported findings for men who have sex with men at CROI 2016, presented findings for women at AIDS 2016. HPTN 069 compared maraviroc-containing regiments to Truvada, making it the first randomized study of HIV PrEP regimens in U.S. women.

The study included 188 people born female over the age of 18. Participants, in the last three months, had  condomless vaginal or anal sex with at least one HIV-positive or unknown status man. The median age of participants was 35, and most were Black (65%).

People in the study received either maraviroc 300 mg; maraviroc 300 mg plus emtricitabine (FTC) 200 mg; maraviroc 300 mg plus tenofovir disoproxil fumarate (TDF) 300mg; or, Truvada (TDF 300 mg + FTC 200 mg). The study lasted 48 weeks.
Study participants were, overall, moderately adherent to the study drug regimen. At week 24, 65% of the sample had detectable study drug in their system; at week 48, 60% of the sample did. There were no new HIV infections during the study. (This study did not assess efficacy, however, so no conclusions can be made yet about how well maraviroc works to prevent HIV in women.)

All of the maraviroc-containing regimens were safe and well-tolerated, as compared to Truvada.
“Maraviroc-containing regiments could be considered for testing in HIV PrEP clinical efficacy trials,” concluded Roy Gulick, MD, MPH of Weill Cornell Medicine.
Benefits of PrEP far outweigh the risks of drug resistance

One concern about PrEP is the potential for drug resistance mutations to develop if HIV infection happens during PrEP delivery (or if PrEP is given to a person who is unknowingly already HIV-positive). People with HIV who develop drug resistant mutations may be effectively limited in their future HIV treatment options. Can the risk of drug resistance be weighed against the HIV prevention benefits of PrEP—as this strategy is provided to an ever-increasing number of people all over the world?

“Resistance infections during PrEP should be weighed against the numbers of infections averted,” said Robert Grant, MD, MPH of the Gladstone Institutes and San Francisco AIDS Foundation. “Each of [these] will require life-long therapy with the attendant risk of virological treatment failure with drug resistance.”
“The risk of drug resistance during PrEP use is rare. It is very low risk,” emphasized Grant. In one review of six PrEP studies by Fonner and colleagues, out of the over 9,000 people took TDF/FTC PrEP only five drug resistant infections emerged, for an overall risk of developing FTC or TDF resistance of 0.05%.

A closer analysis of drug resistant infections in three oral TDF PrEP studies, said Grant, found that there was only one case of TDF resistance—for 53 infections that were averted overall by PrEP use. This one case of resistance that occurred happened because PrEP was give to someone in the acute (early) phase of HIV infection.

Out of five studies of oral FTC/TDF (Truvada), there were eight infections averted for every one drug resistant infection that occurred. Excluding cases of drug resistance that occurred because PrEP was given during early HIV infection, 22 infections were averted for every one case of drug resistant infection.
“Drug resistance risk during PrEP use has been low. And it mostly occurs when starting PrEP during acute HIV infection. Screening for acute infection would increase the benefits relative to drug resistance risk, by more than two-fold,” concluded Grant.