" PURPOSE 1, a Phase 3, double-blind, randomized study, is evaluating the safety and efficacy of twice-yearly, subcutaneous lenacapavir for pre-exposure prophylaxis (PrEP) and once-daily oral Descovy® (emtricitabine 200mg and tenofovir alafenamide 25mg; F/TAF) in more than 5,300 cisgender women and adolescent girls aged 16-25 across 25 sites in South Africa and three sites in Uganda. The drugs are being tested in parallel, with one group receiving twice-yearly lenacapavir and one group taking once-daily oral Descovy. Additionally, a third group was assigned once-daily oral Truvada. Study participants were randomized in a 2:2:1 ratio to lenacapavir, Descovy and Truvada, respectively. Because effective PrEP options already exist, there is broad consensus in the PrEP field that a placebo group would be unethical; thus, the trial used bHIV as the primary comparator and Truvada as a secondary comparator.
There were 0 incident cases of HIV infection among 2,134 women in the lenacapavir group (incidence 0.00 per 100 person-years). There were 16 incident cases among 1,068 women in the Truvada group (incidence 1.69 per 100 person-years). The results demonstrated superiority of twice-yearly lenacapavir over bHIV (primary endpoint, incidence 2.41 per 100 person-years) and superiority of twice-yearly lenacapavir over once-daily Truvada (secondary endpoint), with p<0.0001 for both endpoints. In the trial, lenacapavir was generally well-tolerated and no significant or new safety concerns were identified.
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Gilead expects results in late 2024/early 2025 from the program’s other pivotal trial, PURPOSE 2, which is assessing twice-yearly lenacapavir for PrEP among cisgender men who have sex with men, transgender men, transgender women and gender non-binary individuals who have sex with partners assigned male at birth in Argentina, Brazil, Mexico, Peru, South Africa, Thailand and the United States. "