Breakthrough HIV prevention: Twice-yearly injection shows 100pc efficacy in young women

Clinical trials in South Africa and Uganda have yielded exciting results in the fight against HIV. The study suggests a new long-acting injectable drug, lenacapavir, could be a game-changer in preventing HIV infection, particularly among young women.

The trial compared the effectiveness of a six-month injection of lenacapavir against two existing daily PrEP medications.

According to an interview with Professor Linda-Gail Bekker, the study’s South African lead investigator published in The Conversation Africa, all three drugs fall under the category of pre-exposure prophylaxis (PrEP).

Professor Bekker is a renowned physician-scientist with a deep commitment to research on HIV, tuberculosis and related illnesses. Her doctoral work focused on the body’s response to tuberculosis, both with and without HIV co-infection.

Her research interests have since broadened to encompass programme development and healthcare service delivery related to antiretroviral rollout, TB integration and HIV prevention in women, youth and men who have sex with men.

The Purpose 1 trial, involving 5 000 participants across 25 sites in South Africa and three sites in Uganda, was designed to assess the effectiveness of lenacapavir compared to two other drugs.

“Lenacapavir (Len LA) is a fusion capside inhibitor. It interferes with the HIV capsid, a protein shell that protects HIV’s genetic material and enzymes needed for replication. It is administered just under the skin, once every six months.

“The randomised controlled trial, sponsored by the drug developers Gilead Sciences, tested several things. The first was whether a six-monthly injection of lenacapavir was safe and would provide better protection against HIV infection as PrEP for women between the ages of 16 and 25 than Truvada F/TDF, a daily PrEP pill in wide use that has been available for more than a decade,” said Professor Bekker.

Expanding on Professor Bekker’s insights, the trial also investigated Descovy F/TAF, a newer daily pill, to see if it offered similar protection as F/TDF. Descovy F/TAF boasts improved pharmacokinetic properties, meaning the drug moves through the body more efficiently than F/TDF.

This translates to a smaller pill size, making it potentially more convenient. Notably, Descovy F/TAF is already used for PrEP among men and transgender women in high-income countries.

The study design employed a three-arm approach. Young women were randomly assigned to one of these arms in a 2:2:1 ratio (lenacapavir injection: Descovy F/TAF pill: F/TDF pill). Additionally, it was double-blinded, meaning neither the participants nor the researchers knew who received which treatment until the trial’s conclusion. This approach helps ensure unbiased results.

“During the randomised phase of the trial, none of the 2 134 women who received lenacapavir contracted HIV. There was 100 percent efficiency.

“By comparison, 16 of the 1 068 women (or 1,5 percent) who took Truvada (F/TDF) and 39 of 2 136 (1,8 percent) who received Descovy (F/TAF) contracted the HIV virus. This breakthrough gives great hope that we have a proven, highly effective prevention tool to protect people from HIV,” said Professor Bekker.

She said PrEP must not be taken as the only HIV prevention tool but instead should be provided alongside HIV self-testing, access to condoms, screening and treatment for sexually transmitted infections and access to contraception for women of child-bearing potential.

“Despite these options, we haven’t quite got to the point where we have been able to stop new infections, particularly among young people.

“For young people, the daily decision to take a pill or use a condom or take a pill at the time of sexual intercourse can be very challenging,” she said.

HIV scientists and activists are optimistic that the reduced dosing frequency of lenacapavir (twice-yearly injections) could significantly benefit young people. This shift from daily pills could address challenges like unpredictability and inconsistent adherence.

Furthermore, for young women facing particular obstacles — limited access to clinics, difficulty keeping pills discreet due to stigma or violence — a long-acting injectable option like lenacapavir offers immense promise. This could be the key to preventing HIV infection and empowering them to take control of their health.

According to a press statement from Gilead Sciences, the company is on track to submit the complete data package (dossier) to regulatory bodies in various countries within the next few months. This is a crucial step towards making lenacapavir widely available.

“The World Health Organisation will also review the data and may issue recommendations. We hope then that this new drug will be adopted into WHO and country guidelines. Price is a critical factor to ensure access and distribution in the public sector where it is badly needed,” said Professor Bekker.