Long-acting Injectable Cabotegravir for PrEP Is Promising

Paul E. Sax, MD


June 23, 2020

This transcript has been edited for clarity.

Hello. This is Dr Paul Sax from Brigham and Women's Hospital and Harvard Medical School. Today I'd like to discuss the recently released interim results of HPTN 083. This is a major clinical trial in HIV prevention.

The results are important enough that even though we don't have all the information, I think it's good to review, especially because, in these days, COVID-19 ends up kind of crowding out much of the other ID and HIV news.

This is a randomized clinical trial of pre-exposure prophylaxis in men who have sex with men or transgender women, or transgender men who have sex with men, conducted in multiple countries.

Participants were randomized to receive a standard-of-care treatment of TDF/FTC plus a matching injectable long-acting cabotegravir placebo or the long-acting injectable cabotegravir plus a TDF/FTC placebo. Everyone received active treatment, but there were placebos of each treatment administered as well.

The study enrolled about 4500 people, and during a Data and Safety Monitoring Board review last month, there were very interesting findings in the incidence of HIV. First, the incidence of HIV in the study overall was much lower than expected. They expected between 4% and 5%, partially because they targeted the individuals at highest risk of acquiring HIV, meaning younger men who have sex with men and people who define themselves as black or African American.

They also found about a threefold lower incidence in the cabotegravir arm vs the TDF/FTC arm. There were 50 HIV infections during the course of the study: 38 in the TDF/FTC arm and 12 in the cabotegravir arm.

Now, we didn't get all of the information. Obviously, that is going to be presented in an upcoming scientific meeting and in a paper. One very important piece of information we don't have yet is the occurrence of resistance in those who acquired HIV. Naturally, we are particularly concerned about the occurrence of integrase inhibitor resistance because integrase inhibitors form such an important part of our first-line HIV regimens.

Nonetheless, these are very promising results that imply that the long-acting injectable cabotegravir can reduce one of the weaknesses — or at least deal with one of the weaknesses — of our current pre-exposure prophylaxis approach, which is that it requires an individual to take a pill every day and is therefore very prone to problems with adherence.

Those are the results that we have so far on this exciting clinical trial in HIV prevention, the HPTN 083 study. There is another study, HPTN 084, that is being conducted in women, and it's being done in sub-Saharan Africa.

Thanks very much for listening. Take care.

Paul E. Sax, MD, is a professor of medicine at Harvard Medical School and clinical director of the Division of Infectious Diseases at Brigham and Women's Hospital. His research interests include antiretroviral therapies, the cost-effectiveness of HIV management strategies, and complications of antiretroviral treatment. He blogs at  HIV and ID Observations  and has been a Medscape contributor since 2008.

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