Gilead Sciences has announced positive outcomes from the Phase 3 PURPOSE 1 trial of lenacapavir, demonstrating its efficacy for HIV prevention in cisgender women.

According to topline results from an interim analysis, the twice-yearly injectable HIV-1 capsid inhibitor achieved 100% efficacy in this investigational use.

The PURPOSE 1 trial, part of Gilead Sciences’ PURPOSE programme, met its key efficacy endpoints by showing the superiority of twice-yearly lenacapavir over once-daily oral Truvada (emtricitabine 200mg and tenofovir disoproxil fumarate 300mg; F/TDF) and background HIV incidence (bHIV).

In response to these findings, the independent data monitoring committee (DMC) recommended halting the blinded phase of the trial and providing open-label lenacapavir to all participants.

The late-stage trial, conducted across 25 sites in South Africa and three sites in Uganda, involved over 5,300 cisgender women and adolescent girls aged 16-25.

Participants were randomised into groups receiving twice-yearly lenacapavir, once-daily oral Descovy (emtricitabine 200mg and tenofovir alafenamide 25mg, F/TAF), or once-daily oral Truvada in a controlled study environment.

The trial did not include a placebo group due to ethical considerations within the PrEP field.

Results revealed zero incident cases of HIV infection among 2,134 women in the lenacapavir group, compared to 16 incident cases among 1,068 women in the Truvada group.

The trial also showed that lenacapavir was statistically superior to both bHIV, the primary comparator, and once-daily Truvada, the secondary comparator, with p-values of less than 0.0001 for both comparisons.

The safety profile of lenacapavir was generally favourable, with no significant or new safety concerns identified during the trial.

Gilead Sciences revealed that ongoing analyses will further evaluate adherence to Descovy and Truvada among participants, addressing historical challenges with daily pill adherence in HIV prevention efforts.

Looking ahead, Gilead Sciences anticipates additional trial results from PURPOSE 2, expected in late 2024/early 2025.

PURPOSE 2 focuses on assessing lenacapavir for PrEP among diverse populations including cisgender men who have sex with men, transgender individuals, and gender non-binary individuals across multiple countries.

Positive outcomes from both PURPOSE 1 and PURPOSE 2 trials will support regulatory filings for lenacapavir’s approval as a broad-spectrum HIV prevention option.

Gilead Sciences chief medical officer Merdad Parsey said: “With zero infections and 100% efficacy, twice-yearly lenacapavir has demonstrated its potential as an important new tool to help prevent HIV infections.

“We look forward to additional results from the ongoing PURPOSE clinical programme and continuing toward our goal of helping to end the HIV epidemic for everyone, everywhere.”