Pivotal trial is recruiting for monthly GLP-1 for weight loss | ADA 2026

A phase 3 pivotal trial is recruiting patients and other phase 3 trials are planned for berobenatide, a potential first-in-class monthly GLP-1 receptor agonist (GLP-1), after proof-of-concept studies showed that it can deliver meaningful weight loss. In phase 2b studies, berobenatide delivered continuous weight loss at all doses selected for the phase 3 trial with a tolerable safety profile both for people with or without Type 2 diabetes, according to data released at the 86th Scientific Sessions of the American Diabetes Association (ADA).

“Berobenatide is a potentially important new option for people living with overweight or obesity, especially because a once-monthly dosing could offer a more manageable alternative to today’s more frequent injections,” lead author John B. Buse, M.D., Ph.D., professor of Medicine at the University of North Carolina School of Medicine, Chapel Hill, said in a news release. “For patients, this less frequent dosing may help ease the burden of ongoing treatment and support better long-term adherence in chronic conditions like obesity and type 2 diabetes.”

Developed by Pfizer, berobenatide is an ultra-long GLP-1 that is designed to stay attached to the blood protein albumin, which slows it from breaking down too quickly.

Pfizer plans to develop the therapy as an autoinjector product. The company’s research shows that both patients and healthcare professionals would prefer a longer-acting, monthly option, which they said in a recently investor presentation could help with patient adherence. Pfizer also plans to have a direct-to-consumer cash pay option available at launch of berobenatide.

Results from the VESPER-3 trial suggest berobenatide can be dosed monthly, with effective weight loss and favorable tolerability in individuals living with overweight or obesity. VESPER-3 is a 2b trial evaluating whether berobenatide can successfully transition from once-weekly to once-monthly dosing while still maintaining weight loss and tolerability in patients who are obese, including those with and without Type 1 diabetes.

After 28 weeks of treatment, berobenatide demonstrated a placebo-adjusted weight loss of up to 12.3% with the 4.8 mg monthly dose. The safety and tolerability were consistent with the GLP-1 RA class. The final endpoint of the VESPER-3 study will be assessed at 64 weeks.

Researchers also presented data from the 32-week exploratory extension (Part B) of the phase 2b VESPER-1 study, which showed a non-placebo-adjusted weight loss of 15.9% with no plateau in weight loss seen. VESPER-1 is evaluating once-weekly berobenatide in adults with obesity or who are overweight. Part B is being done to assess the durability of weight loss and the impact of transitioning from once-weekly to once-monthly dosing.

In addition, data from the phase 2b VESPER-2 study were presented. This study evaluated weekly dosing of berobenatide in adults with obesity or overweight and Type 2 diabetes. This trial found there was a 2.2% reduction in HbA1c achieved with berobenatide 1.6 mg weekly at week 28, compared with a reduction of 0.2% in the placebo group.

Pfizer officials said they are enrolling patients in the VESPER-6 pivotal phase 3 study evaluating monthly maintenance dosing for berobenatide in adults with obesity or overweight. The phase 3 program will include 10 studies for chronic weight management and obesity-related comorbidities. Berobenatide will be studied both as a single agent and in combination with other therapies.

Berobenatide was part of Pfizer’s acquisition of Metsera, which was completed in November 2025 for $7 billion. Also part of this acquisition was a monthly amylin analog candidate for obesity and an oral GLP-1 RA candidate.