PF-08653944 (GLP-1 Receptor Agonist)

February 3, 2026 — Pfizer Inc. (NYSE: PFE) announced positive topline results from the Phase 2b VESPER-3 trial of PF-08653944 (PF’3944; previously MET-097i), a fully biased, ultra-long-acting injectable GLP-1 receptor agonist, testing a switch from weekly titration dosing (to week 12) to monthly maintenance dosing (to week 28) in adults with obesity or overweight without type 2 diabetes.

The study met its primary endpoint: weight reduction from randomization to week 28 was superior to placebo across all four dose regimens (P<0.001). At week 28, placebo-adjusted weight loss reached up to 12.3% (efficacy estimand), with 10% (Arm 1; low monthly regimen) and 12.3% (Arm 3; medium monthly regimen) achieved in the Phase 3-planned monthly maintenance regimens; no plateau was observed at week 28.

Safety/tolerability through week 28 was consistent with GLP-1 RAs; GI events were mostly mild/moderate, with ≤1 severe nausea/vomiting per dose group and no severe diarrhea. Discontinuations due to AEs: 5 in Arms 1/3 during weekly phase and 5 during monthly phase; 0 in placebo. Pfizer said detailed data will be presented June 6, 2026 (ADA Scientific Sessions) and plans 10 Phase 3 PF’3944 trials in 2026, including VESPER-4 (weekly; initiated), VESPER-5 (weekly; planned) and VESPER-6 (monthly; planned).