Long-Acting Injectable PrEP Drug Shown to Prevent HIV Among MSM & Transgender Women
by Hank Trout
On May 18, 2020, the National Institutes of Health and ViiV Healthcare announced the early ending of an HIV Prevention Trials Network (HPTN) study of an investigational long-acting form of PrEP, an injectable HIV drug called cabotegravir. The study suggests that, injected once every 8 weeks, cabotegravir safely and effectively prevents HIV acquisition in men who have sex with men (MSM) and transgender women who have sex with men.
In the study, called HPTN 083, cabotegravir was found to be 69% more effective in preventing HIV acquisition in MSM and transgender women who have sex with men when compared to the only current available regimen of daily oral tablets. This finding marks the first time a large-scale clinical trial has shown a systemic, long-acting form of HIV prevention to be highly effective.
The NIH explained that for people who feel healthy, taking a daily oral pill such as Truvada or Descovy, the only currently FDA-approved form of HIV pre-exposure prophylaxis (PrEP), can be challenging. Investigators have been trying to develop a long-acting alternative to oral PrEP that would be at least equally effective at preventing HIV and offer an option that may be easier for some people to adhere to. “New options are needed for HIV prevention that offer an effective alternative to daily oral PrEP. If approved, this long-acting injectable has the potential to be a game-changer for HIV prevention by reducing the frequency of dosing from 365 days to six times per year,” Kimberly Smith, M.D., Head of Research & Development at ViiV Healthcare, said in a press release.
The HPTN 083 study team began in November 2016 enrolling 4,570 HIV-negative at-risk men who have sex with men and transgender women who have sex with men at forty-three distinct sites in South America, South Africa, Thailand, North America, and Vietnam. Most of the study participants were under thirty years of age, and 12% were transgender women. All agreed to participate for a maximum of three years. Participants were randomly assigned to receive either injections of cabotegravir and placebo oral tablets, or placebo injections and daily oral Truvada tablets. Neither the participants nor the study team knew who was receiving which medication.
Of the 4,570 participants, fifty acquired HIV despite the treatment. Of those fifty, thirty-eight (1.21% of the 4,570) were receiving oral Truvada, and only twelve (0.38%) were receiving the cabotegravir injections. Both treatments were judged generally safe and well-tolerated, although 80% of the participants receiving the cabotegravir reported some soreness around the injection site.
After reviewing the results of the study at its planned interim review on May 14, 2020, the Data and Safety Monitoring Board (DSMB) found that the study data clearly indicated that long-acting injectable cabotegravir was highly effective at preventing HIV and recommended that this portion of the study, originally planned to continue through 2021, be stopped early and the results released.
“These study results demonstrate that long-acting injectable cabotegravir dosed every two months can successfully reduce HIV acquisition in at-risk MSM and transgender women,” said Dr. Smith. “We are thrilled with the results not only because of the high efficacy of cabotegravir but also because we have demonstrated high efficacy in a study that adequately represents some of the populations most disproportionately impacted by HIV—black MSM in the U.S., young MSM globally and transgender women,” she said.
The DSMB also reviewed data from HPTN 084, an ongoing companion study which began a year later than HPTN 083, evaluating long-acting injectable cabotegravir for HIV prevention in women in east and southern Africa. More than 3,000 sexually active women in seven African countries have enrolled in HPTN 084. After review, the DSMB recommended that the HPTN 084 trial continue. “We are also committed to studying the effectiveness of cabotegravir in women and continue to be focused on the completion of HPTN 084,” Dr. Smith reported.
Hank Trout, Senior Editor, edited Drummer, Malebox, and Folsom magazines in the early 1980s. A long-term survivor of HIV/AIDS (diagnosed in 1989), he is a forty-year resident of San Francisco, where he lives with his husband Rick Greathouse. Follow him on Twitter @HankTroutWriter.