Major Africa study makes important breakthrough in HIV prevention

Women make more than half of the people living with HIV worldwide. Young women between the ages of 10 and 24 are twice as likely to get HIV as young men in the same age group. In East and Southern Africa, young women get HIV on average five to seven years earlier than their male counterparts.

Researchers have worked hard to be effective HIV prevention measures.

Most notable is the pre-exposure prophylaxis (PrEP), known as Truvada. It is a combination of two antiretroviral drugs – tenofovir and emtricitabine. It can be effective in preventing HIV acquisition. But drinking a pill daily is not practical for many people.

Scientists from the HIV prevention trial network recently found that a PrEP regimen of long-acting cabotegravir (CAB LA) injections once every eight weeks was better than the daily tablet used to prevent HIV. Ina Skosana spoke to Sinead Delany-Moretlwe, a research professor at the University of the Witwatersrand in South Africa and director of research at the Wits Reproductive Health & HIV Institute, to find out more.

Can you tell us about the study?

This study, known as HPTN 084 is the first to compare the efficacy of two prevention or pre-exposure prophylaxis.

The first treatment consisted of an injection of the long-acting antiretroviral drug, given cabotegravir every eight weeks. The second treatment was the daily oral dose of Truvada. Truvada has been shown to be very effective in preventing HIV when prescribed in different populations and contexts.

We enrolled more than 3,200 sexually active, HIV-uninfected cisgender women at 20 locations in seven countries. Research took place between November 2017 and November 2020 in Botswana, Eswatini, Kenya, Malawi, South Africa, Uganda and Zimbabwe.

Our study randomized participants to one of the two arms. One arm received active cabotegravir and a Truvada placebo. The other arm received active Truvada and placebos for cabotegravir. Cabotegravir was administered orally daily for 5 weeks and by intramuscular injections at 8-week intervals after an initial 4-week interval loading.

What did you find?

Preliminary findings show that 1% of the participants in the study period were infected with HIV. This suggests that both cabotegravir and Truvada are very effective in preventing HIV in this population.

The 34 incident infections detected in Truvada participants are equivalent to a 1.79% incidence. And the four infections detected among the participants in cabotegravir are equal to an incidence of 0.21%. This confirms a new prevention option for women that offers a significant advantage over existing oral PrEP, which consistently requires daily use and is associated with significant compliance challenges.

We observed about 9 times the number of HIV infections in the Truvada arm compared to the cabotegravir arm. This finding suggests that cabotegravir is much more effective than Truvada in preventing HIV infection in women. And the threshold for the early stop of the trial has been reached. Based on these findings, the Independent Safety and Security Monitoring Board recommended that the blinded portion of the study be stopped early and the results made known to the scientific and wider community.

A previous sibling study among men and transgender women was called HPTN 083 similar results shown. A preparation regimen with long-acting cabotegravir injection once every 8 weeks was better than the daily oral Truvada in the population.

What are the next steps?

The results of the study are important and timely, as more methods are urgently needed to prevent HIV among women at higher risk for HIV. These include methods that do not depend on the daily or near-daily intake of pills, the use of condoms or the abstinence from sex. The development of alternative methods to prevent HIV, and more compliance-friendly schedules than are currently available, will increase the choice and acceptability of HIV for women and reduce new HIV infections.

We have been in contact with the research ethics committees and national drug regulators overseeing this study, and site investigators and study participants will be notified of the results as soon as possible. Participants will be able to learn about the medication they received. A protocol amendment will be submitted for regulatory review to enable participants to continue administering medication or to switch to cabotegravir if they prefer.

Participants in Truvada will be offered cabotegravir as soon as the medication can be made available. All participants will be asked to continue with the study. And if they choose not to stay in the study, they will be referred to the best local HIV prevention services. We look forward to presenting these results during upcoming conferences in a peer review environment as we finalize the primary analysis.

Sinead Delany-Moretlwe, Associate Professor and Director: Research at the Wits Reproductive Health and HIV Institute I, University of the Witwatersrand

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