Single Oral Doses of MK-8507, a Novel Non-Nucleoside Reverse Transcriptase Inhibitor, Suppress HIV-1 RNA for a Week

Background MK-8507 is a novel HIV-1 non-nucleoside reverse transcriptase inhibitor being developed for treatment of HIV-1 infection. MK-8507 has high antiviral potency in vitro and pharmacokinetic (PK) properties that support once-weekly dosing. Setting A phase 1, open-label, proof-of-concept study was conducted in treatment-naive adults with HIV-1 infection to assess monotherapy antiviral activity. Methods In 3 sequential panels, participants aged 18-60 years with baseline plasma HIV-1 RNA ≥10,000 copies/mL and CD4+ T-cell count >200/mm3 received a single oral dose of 40, 80, or 600 mg MK-8507 in the fasted state. Participants were assessed for HIV-1 RNA for at least 7 days, PK for 14 days, and safety and tolerability for 21 days post dose. Results A total of 18 participants were enrolled (6 per panel). The mean 7-day post-dose HIV-1 RNA reduction ranged from ∼1.2 to ∼1.5 log10 copies/mL across the doses assessed. One patient had a viral rebound associated with emergence of a F227C reverse transcriptase variant (per chain-termination method sequencing) 14 days post dose; this variant was found in a second participant by ultra-deep sequencing as an emerging minority variant. MK-8507 PK were generally dose-proportional and similar to observations in participants without HIV-1 infection in prior studies; mean MK-8507 half-life was 56-69 hours in this study. MK-8507 was generally well tolerated at all doses. Conclusions The robust antiviral activity, PK, and tolerability of MK-8507 support its continued development as part of a complete once-weekly oral regimen for HIV-1 treatment; combination therapy could mitigate the emergence of resistance-associated variants.