Pfizer Advances PF’3944 Into Phase III After Positive VESPER-3 Data

Pfizer is preparing an extensive Phase III programme for its acquired obesity therapy PF’3944, following encouraging Phase IIb results from the VESPER-3 trial (NCT06973720). The once-monthly glucagon-like peptide-1 receptor agonist (GLP-1RA), previously known as MET-097i, maintained weight loss after patients switched from weekly to monthly dosing.

In adults with obesity or overweight without type 2 diabetes, PF’3944 achieved mean placebo-adjusted weight reductions of 10% and 12.3% at week 28 across two cohorts. No weight-loss plateau was observed, suggesting further reductions may occur through week 64. The therapy also demonstrated a safety and tolerability profile consistent with the GLP-1RA class.

Pfizer acquired MET-097i through its $10bn purchase of Metsera in November 2025. Detailed VESPER-3 results will be presented at the 86th Scientific Sessions of the American Diabetes Association.

Phase III plans include the VESPER-4, VESPER-5 and VESPER-6 trials, as Pfizer positions PF’3944 against obesity leaders Novo Nordisk and Eli Lilly.

17-02-2026