Resistance Analysis of Low-Level Virologic Rebound During HIV-1 Treatment With Lenacapavir and Broadly Neutralizing Antibodies Teropavimab and Zinlirvimab.

BACKGROUND: High rates of virologic suppression were observed in the Phase 1b study (NCT04811040) investigating lenacapavir and two broadly neutralizing antibodies (bNAb), teropavimab (30 mg/kg) and zinlirvimab (10 or 30 mg/kg), in virologically suppressed people with HIV-1 susceptible (IC90 ≤ 2 μg/mL) to both (primary cohort, n = 20) or either (pilot cohort, n = 10) bNAb. We describe resistance analyses through Week (W) 26. METHODS: Post-baseline resistance analyses were conducted at virologic failure, and exploratory resistance analyses performed for participants with virologic rebound. Low copy number genotyping methods for capsid and a 1 kb stretch of gp120 from rebound virus were developed, and phenotypic susceptibility assessed. RESULTS: Virologic failure was observed in 1/30 participants. This primary cohort participant had HIV RNA 155 copies/mL at W16 and developed Q67H in capsid (lenacapavir fold-change 4.7), without resistance to bNAbs; the participant resuppressed on oral antiretrovirals. Two pilot cohort participants, experienced virologic rebound at W26 (55 and 72 copies/mL) and restarted oral antiretrovirals. In exploratory analyses, neither had emergent lenacapavir resistance or altered bNAb susceptibility. CONCLUSIONS: Lenacapavir, teropavimab, and zinlirvimab maintained a high rate of virologic suppression through W26, with rare emergent lenacapavir resistance and no bNAb resistance, supporting further Phase 2 evaluation.