epocrates

Monthly GLP-1 injection demonstrates significant weight loss in phase 2b trial

February 17, 2026

Results from Pfizer's phase 2b VESPER‑3 trial (NCT06973720) showed that ultra–long‑acting GLP‑1 receptor agonist (RA) PF’3944 achieved statistically significant weight loss, with up to 12.3% mean placebo‑adjusted reduction at week 28, meeting the study’s primary endpoint. Weight loss continued after transitioning from weekly to monthly dosing, with no plateau observed. Study design incorporated weekly titration through week 12 followed by monthly injections through week 28 across four dosing regimens, all of which outperformed placebo (P < 0.001). Safety was consistent with the GLP‑1 RA class, with predominantly mild to moderate GI adverse events and a generally well‑tolerated profile. Pfizer plans to advance 10 phase 3 trials in 2026 to further evaluate PF’3944.

Clinical takeaway: PF’3944 may emerge as a meaningful once‑monthly alternative to weekly GLP‑1 RAs, offering sustained weight loss with reduced injection burden, potentially improving adherence for adults with obesity or overweight without type 2 diabetes.

Source:

Pfizer’s Ultra-Long-Acting Injectable GLP-1 RA Shows Robust and Continued Weight Loss with Monthly Dosing in Phase 2b Trial. [News release]. 2026. https://www.pfizer.com/news/press-release/press-release-detail/pfizers-ultra-long-acting-injectable-glp-1-ra-shows-robust