A phase I, first‐in‐human study investigating the safety, tolerability, and pharmacokinetics of the maturation inhibitor GSK3739937

We report the safety and pharmacokinetic properties of the HIV‐1 maturation inhibitor GSK3739937 (GSK'937) in healthy participants. This was a phase I, first‐in‐human, double‐blind, randomized, placebo‐controlled, single‐ (part 1) and multiple‐ (part 2) dose escalation study with an additional open‐label relative bioavailability and food effect study (part 3). Participants received oral ascending single doses (10–800 mg) in part 1, up to 18 once‐daily 25‐ to 100‐mg or 3 once‐weekly 500‐mg doses in part 2, and single 100‐mg doses as powder‐in‐bottle or tablet (in fed and fasted states) formulations in part 3. Primary and secondary objectives were safety and pharmacokinetic assessments, respectively. Ninety‐one participants were enrolled; 38 reported 81 total adverse events (AEs). All AEs in participants receiving GSK'937 were grade 1 or 2 and resolved during the study. Most drug‐related AEs were gastrointestinal (14/17, 82%). The terminal phase half‐life of GSK'937 was ~3 days for all doses following single and repeat dosing. Geometric mean maximum concentration and total drug exposures exhibited dose‐proportional increases during part 1. Accumulation in exposure following repeat dosing was 6‐ to 7‐fold with daily dosing and ~1.7‐fold after weekly treatment, as expected due to the long half‐life. Bioavailability of GSK'937 after a meal was 1.35‐ to 1.40‐fold greater as a tablet versus powder‐in‐bottle and >2‐fold higher in fed versus fasted states when provided as a tablet. No unexpected or dose‐limiting safety events occurred. Pharmacokinetic parameters of long half‐life and accumulation of exposure following repeat dosing suggest the potential for weekly oral dosing. ClinicalTrials.gov identifier: NCT04493684.