New Shot at HIV Prevention
A New Shot at HIV Prevention
Clinical trial HPTN 083, a safety and efficacy study of injectable cabotegravir compared to daily oral Truvada for HIV pre-exposure prophylaxis (PrEP), was ended earlier than expected in May of this year. The results from this study show that cabotegravir administered every 8 weeks provides greater efficacy for HIV prevention compared to Truvada.
This double-blind trial was conducted in 4,570 cisgender men and transgender women who have sex with men at 43 sites in Argentina, Brazil, Peru, the United States, South Africa, Thailand, and Vietnam (HIV Prevention Trials Network). This trial is being praised for its diversity, as it was mandated that at least half of the participants had to be black men who have sex with men, the population most severely affected by HIV in the United States. Typically, HIV-related clinical trials are mostly made up of older white gay men who join them for access to new drugs (Mandavilli, 2020).
Participants in the study were randomly assigned to one of two groups. Participants in each group received both injections and oral tablets, with one containing an active drug and the other a placebo. During the course of the study 50 incident (new) HIV infections occurred, 38 (1.21%) in the Truvada group and 12 (0.38%) in the cabotegravir group. Put another way, approximately 3 times the number of incident cases was seen in the group which took daily Truvada as compared to the group that received the cabotegravir injection every 8 weeks. This equates to a 66% reduction in the incidence of HIV infections in the cabotegravir group as compared to the Truvada group (HIV Prevention Trials Network).
This is an important development for HIV PrEP users as it increases their HIV prevention options. Many providers and researchers also acknowledge that adherence to daily oral pill regimens can be challenging to maintain, so an injection every two months will likely be appealing to many people (International AIDS Conference, 2020). Periodic injections may also be seen as a more discreet form of HIV PrEP as it will require fewer visits to HIV clinics and pharmacies.
Currently there are only two drugs approved by the Food and Drug Administration (FDA) for the use of HIV PrEP in the United States, Truvada and Descovy, both made by Gilead Sciences. Truvada is approved for use in all at risk adults, but Descovy is only approved for use in cisgender men and transgender women (the populations Gilead tested the drug in) leaving cisgender women and transgender men vulnerable if they cannot take Truvada for any reason (Mandavilli, 2020).
ViiV Healthcare, who conducted the HPTN 083 trial, say that the drug is not yet being tested in transgender men so it seems likely that when they file for FDA approval in early 2021 that the same populations will miss out on the approval to receive this drug and be left with Truvada as their only option (Mandavilli, 2020). There is currently an ongoing trial in cisgender women in South Africa, but it appears results in that population may not be available in time for the FDA filing (HIV Prevention Trials Network). There is some good news for anyone interested in HIV PrEP: Truvada is expected to be available in a generic form next year, lowering the cost of this important infection preventing drug (Mandavilli, 2020).
References:
Centers for Disease Control and Prevention. (2020). HIV in the United States and dependent
areas. Retrieved on July 31, 2020 from https://www.cdc.gov/hiv/statistics/overview/ataglance.html
HIV Prevention Trials Network. (n.d.). HPTN 083. Retrieved on July 30, 2020 from
https://www.hptn.org/research/studies/hptn083
International AIDS Conference. (2020). Important HIV Prevention, treatment and cure research
unveiled at AIDS 2020: Virtual. Retrieved on July 30, 2020 from https://www.aids2020.org/important-hiv-prevention-treatment-and-cure-research-unveiled-at-aids-2020-virtual/
Mandavilli, A. (2020, July 7). A shot to protect against H.I.V. The New York Times. Retrieved on
July 30, 2020 from https://www.nytimes.com/2020/07/07/health/hiv-shot-prep.html