Gilead's Phase 1 Data Shows Promise For Once-Yearly Lenacapavir In HIV Prevention

(RTTNews) - Gilead Sciences Inc. (GILD) announced that phase 1 study data showed two different formulations of once-yearly lenacapavir, administered via intramuscular injection, achieved and maintained plasma concentrations exceeding those associated with HIV prevention efficacy observed in the Phase 3 PURPOSE 1 and PURPOSE 2 trials.

The company presented the first data from its ongoing Phase 1 study investigating two novel, once-yearly formulations of lenacapavir, the company's injectable HIV-1 capsid inhibitor, for the investigational use of HIV prevention as pre-exposure prophylaxis (PrEP). The data were presented during an oral abstract session at the Conference on Retroviruses and Opportunistic Infections or CROI 2025 and were also published today in The Lancet. Data will support the future development of once-yearly lenacapavir for PrEP, for which Gilead plans to launch a Phase 3 study in the second half of 2025.

The Phase 1 study evaluated the pharmacokinetics, safety and tolerability of two intramuscular single-dose 5000mg lenacapavir formulations. The trial included 40 healthy adults at low risk of HIV acquisition, between the ages of 18 and 55 years, with a body mass index of less than or equal to 35.0 kg/m2.

According to the company, Lenacapavir plasma concentrations for participants remained above the 95% effective concentration for at least 56 weeks with both formulations. Furthermore, median trough concentrations of both formulations of once-yearly lenacapavir at Week 52 (57.0 ng/mL and 65.6 ng/mL) were higher than those observed with twice-yearly lenacapavir in the PURPOSE 1 and PURPOSE 2 trials at Week 26 (23.4 ng/mL). Data from the study confirmed that both once-yearly formulations of lenacapavir warrant further investigation.

The company noted that once-yearly lenacapavir is being investigated as an intramuscular injection. This is different from the subcutaneous formulation of lenacapavir, which is being investigated for twice-yearly dosing. The most commonly reported adverse event for both intramuscular formulations studied was injection site pain, which was mostly mild in severity and resolved within 1 week (occurred in 80% of participants receiving formulation 1, and 75% receiving formulation 2), and was reduced by pretreatment with an ice pack. Medication-emergent adverse events were similar between the two cohorts and mostly mild to moderate in severity.

New quantitative and late-breaking qualitative survey data from the PURPOSE 1 trial, evaluating twice-yearly subcutaneous lenacapavir for PrEP among cisgender women in sub-Saharan Africa, were presented at CROI in two poster sessions. An interim analysis of surveys included 2,561 trial participants' self-reported preferences for twice-yearly lenacapavir injections and once-daily pills. Approximately two-thirds of survey respondents preferred twice-yearly lenacapavir at Week 52 of their trial participation, compared to fewer than one-third who preferred once-daily pills.

Additionally, at Week 52, most respondents (61%) reported feeling more protected from HIV with twice-yearly PrEP injections compared to once-daily pills. Similarly, 61% of respondents felt more confident about not missing a PrEP dose with twice-yearly injections compared to once-daily pills. Qualitative data from 108 participants also showed that respondents, particularly adolescents aged 16 and 17 years, noted that twice-yearly injections better suited their lifestyles compared to once-daily pills.

The company noted that PURPOSE 1 is the first adult Phase 3 HIV prevention trial to intentionally include adolescents aged 16 and 17 years, and trial enrollment was much higher than in typical adolescent-dedicated studies (124 adolescents, 56 of whom were assigned to the lenacapavir group).

The data showed that observed lenacapavir plasma concentrations were comparable between adolescent and adult trial groups, with participants in both groups experiencing the same most common adverse events. There were zero incident HIV infections across the adolescent and adult groups receiving lenacapavir. Given these results, data submitted to regulatory authorities support the potential use of twice-yearly lenacapavir for adolescents who need or want PrEP.

Lenacapavir is approved in multiple countries for the treatment of adults with multi-drug resistant HIV in combination with other antiretrovirals. The use of lenacapavir for HIV prevention is investigational and the safety and efficacy of lenacapavir for this use have not been established.

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