Pfizer Inc. reported that its investigational GLP-1 receptor agonist, berobenatide, achieved a 15.9% non-placebo-adjusted weight loss in participants during Phase 2b studies. The data, presented on Saturday, supports the company's position in the obesity treatment market as it prepares for a broader Phase 3 program. Pfizer shares were trading lower by almost 1% on Monday following the announcement.

The Phase 2b VESPER-1 study included a 32-week exploratory extension where participants who escalated from placebo to 2.4 mg weekly berobenatide showed a 15.9% weight loss with no plateau observed at 32 weeks. This marks the first presentation of clinical experience with the top weekly dose for berobenatide.

Pfizer plans to initiate 10 Phase 3 studies for berobenatide in 2026 targeting chronic weight management and obesity-related comorbidities, including knee osteoarthritis and obstructive sleep apnea. This effort is part of a larger program comprising over 20 obesity trials. The pivotal VESPER-6 Phase 3 study, investigating monthly maintenance dosing, is currently open for enrollment.

Clinical Pipeline Expansion

The company is also progressing the SOLIS-1 Phase 2b study, which evaluates weekly and monthly maintenance dosing of an ultra-long-acting amylin analog (PF'3945). This study is assessing the analog as a monotherapy and in combination with berobenatide.

Regulatory Approval for HYMPAVZI

Separately, the U.S. Food and Drug Administration (FDA) approved an expanded indication for Pfizer's HYMPAVZI (marstacimab-hncq). The approval now includes hemophilia A or B patients 12 years and older with inhibitors, as well as pediatric patients aged 6 to 11 years with or without inhibitors. HYMPAVZI is the first subcutaneous non-factor therapy available for pediatric patients with hemophilia B in this age group.