‘Miracle’ prevention drug, new PrEP options and innovation in tackling STIs among highlights from HIVR4P 2024

The 5th HIV Research for Prevention (HIVR4P) conference was held in Lima, Peru, from October 6th to 10th, 2024. It showcased groundbreaking developments in HIV prevention and research. Read on to find some of our highlights.

The 'miracle' HIV prevention drug continues to prove its effectiveness

Results from the PURPOSE 2 trial found that lenacapavir, an injectable HIV prevention drug providing six months of protection, was highly effective. Enrolling over 3,200 participants from Argentina, Brazil, Mexico, Peru, South Africa, Thailand, and the U.S. between June 2021 and December 2023, the trial compared lenacapavir injections every six months to daily oral PrEP (TDF/FTC).

After 39 weeks, only two HIV cases occurred in the lenacapavir group, which had 2,179 individuals, resulting in a 96% reduction in HIV incidence, while nine infections were recorded among those taking daily oral PrEP. Lenacapavir proved 89% more effective than oral PrEP.

Earlier findings from the PURPOSE 1 trial announced during the AIDS conference this July, demonstrated 100% efficacy in preventing HIV among 2,134 cisgender women in South Africa and Uganda, with Winnie Byanyima, executive director of UNAIDS calling the drug a “miracle tool”. On access, Gilead, the manufacturer of LEN, announced royalty-free agreements with six pharmaceutical companies to produce generic versions of lenacapavir for 120 countries with high HIV incidence.

PrEP implant technology

The current options for pre-exposure prophylaxis (PrEP) include oral pills, injectables, and controlled-release vaginal rings. However, delegates were presented at the conference with a new refillable antiretroviral drug implant placed under the skin. Unlike traditional implants, this device can be refilled with a minimally invasive injection through the skin, allowing for potential long-term use.

The study results from monkeys showed that implants containing the drug islatravir provided 100% protection against rectal and vaginal hybrid human/simian virus similar to HIV for over 29 months without needing refills. Similarly, when loaded with MK-8527, a different antiretroviral drug, the implant was also tolerable and sustained drug release.

This technology has the potential to simplify HIV care and may eventually be combined with contraceptives for even broader health benefits. The implant could be a game-changer, particularly for those seeking a longer-lasting, low-maintenance method of HIV prevention.

One injection for contraception and HIV prevention

A new silica-based hydrogel injectable, combining an HIV prevention drug and contraception, proved to offer dual protection in a single shot. This injectable combines long-acting cabotegravir (CAB-LA) with the contraceptive levonorgestrel (LNG), providing protection for up to three months with just one injection.

Preclinical tests in rats showed sustained levels of both drugs with no significant drug interactions or safety issues. Additional studies in non-human primates are ongoing to refine dosing and duration. This innovative approach could greatly benefit regions where HIV and unintended pregnancies are common.

Expedited partner therapy in tackling STIs among young people

According to the World Health Organization, over 1 million curable sexually transmitted infections (STIs) occur daily, with many going undiagnosed. Asymptomatic STIs in adolescent girls and young women often remain untreated, increasing the risk of HIV. The ARISE cohort study in Johannesburg aimed to provide point-of-care testing and treatment for women aged 18-25 using or interested in PrEP.

From February 2022 to December 2023, 305 young women were tested for STIs. Baseline STI prevalence was 80% for chlamydia, 20% for both gonorrhoea and trichomoniasis, while 35% reported STI-related symptoms. Participants received treatment within 90 minutes and were offered expedited partner therapy (EPT) for their sexual partners. EPT is a clinical practice where patients diagnosed with chlamydia or gonorrhea are given prescriptions to pass on to their sexual partners, without the partner needing to be examined by a healthcare provider first to ensure timely treatment.

After one month, infection rates among participants who delivered EPT to their primary partners dropped significantly: chlamydia fell to 10%, gonorrhoea to 7%, and trichomoniasis to 10%. These findings suggest that point-of-care testing and EPT can significantly reduce STI transmission and improve treatment completion rates, especially for asymptomatic individuals.

No interactions between long-acting PrEP and hormonal contraceptives

A sub-study of HPTN 084 explored the possible interactions between long-acting PrEP (CAB-LA) and hormonal contraceptives. The study enrolled 170 participants who used either CAB-LA or oral PrEP along with three contraceptives: etonogestrel, medroxyprogesterone acetate, and norethindrone. The results showed no significant interactions between CAB-LA and contraceptives, meaning both drugs worked effectively without affecting each other. The findings were reassuring: plasma concentrations of the contraceptives remained comparable between the CAB-LA and oral PrEP groups, indicating that CAB-LA does not interfere with contraceptive effectiveness

Rectal tenofovir douche shows high acceptability as on-demand HIV prevention

Some men who have sex with men practice douching, a process of flushing the rectum with water or saline to feel cleaner before anal sex. Researchers in the U.S. have developed an on-demand rectal tenofovir (TFV) douche as pre-exposure prophylaxis (PrEP) to prevent HIV during receptive anal intercourse, addressing a critical gap in PrEP options.

HIV-negative men who have sex with men took part in a Phase I trial to test the safety and effectiveness of a single-dose 125 ml rectal douche containing 660 mg of tenofovir. The trial also assessed how well the participants accepted the product. The douche was administered rectally. Participants rated it highly, with an average score of 9 out of 10. Every participant said they would recommend using it. Most (75%) had douched previously and appreciated how this PrEP option aligned with their routine, with most participants (80%) preferring the TFV douche over daily oral PrEP

The promising results suggest the TFV douche could be an effective, on-demand HIV prevention tool for men who have sex with men, warranting further clinical development.

Other findings from HIVR4P 2024, including a 3-month vaginal PrEP ring, show the rapid advancements being made in HIV prevention and care, offering new hope for tackling the HIV epidemic and improving overall sexual health worldwide.