On the heels of a strong showing for the drug earlier this year, Pfizer is padding the case for the GLP-1 receptor agonist it picked up in its $10 billion purchase of obesity biotech Metsera.
At the American Diabetes Association Scientific Sessions in New Orleans, Pfizer on Saturday unveiled the first “clinical experience” with the top weekly dose of the peptide drug berobenatide, also coded PF-08653944 and previously known as MET-097i.
In a 32-week extension of its phase 2b VESPER-1 study, patients with obesity or overweight who escalated from placebo to a 2.4 mg weekly dose of berobenatide achieved a non-placebo-adjusted weight loss of 15.9% with no plateau, according to a release.
It remains to be seen how the medicine will ultimately stack up against the field’s frontrunners with more clinical experience. Lilly’s approved Zepbound has shown 20.9% weight loss after 72 weeks in a late-stage trial, while Novo Nordisk reported an 18.7% weight loss result for the high dose of Wegovy after the same amount of time. Cross-trial comparisons naturally carry inherent flaws, and in this case industry watchers will want to see the power of berobenatide over a longer timeframe.
In another update from Pfizer and Metsera’s broader berobenatide program, detailed results from the phase 2b VESPER-2 study—which looked at weekly dosing of the candidate in adults with obesity or overweight and Type 2 diabetes—found that berobenatide helped trigger dose-dependent reductions from baseline across both body weight and HbA1c.
Specifically, Pfizer flagged a 2.2% reduction in blood sugar levels with berobenatide given at 1.6 mg weekly versus a 0.2% reduction on placebo.
In a statement, Pfizer Chief Internal Medicine Officer Jim List, M.D., Ph.D., said the studies showed that the drug candidate “delivered continuous, uninterrupted weight loss at all doses selected for Phase 3, while preserving a tolerable profile as people transitioned from a weekly to a monthly maintenance dose.”
Pfizer is planning to advance 10 late-stage programs for berobenatide in 2026, both for chronic weight management and obesity-related comorbidities like knee osteoarthritis and obstructive sleep apnea.
The aim reflects a broader trend in which developers of next-generation incretin meds for obesity are looking to tackle metabolic health more holistically, rather than focusing on mean weight loss alone. As it stands, Pfizer and Metsera have already kicked off work on additional VESPER trials 4 through 6.
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VESPER-4 is a phase 3 trial looking at once-weekly berobenatide in patients with obesity without Type 2 diabetes, while VESPER-5 is testing the drug in patients who also have diabetes, as well as assessing a higher, 2.4 mg dose.
The plan for the late-stage VESPER-6, meanwhile, is to look at berobenatide in patients with obesity and overweight when dosed just once a month.
Pfizer pulled back the curtain on berobenatide after reporting out data on VESPER-3 in February.
In that phase 2b study, which randomized around 250 adults with obesity or who were overweight without Type 2 diabetes, Pfizer reported placebo-adjusted weight loss of 10% and 12.3%, respectively, at week 28 on the low and medium monthly dosing regimens the company is taking into phase 3.
“On their face, the headline weight loss of 12.3% at 28 weeks look competitive, especially in the context of ongoing studies in combination with the company’s amylin asset MET-233i,” BMO Capital Markets analysts said of the data earlier this year.
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After previously stumbling in the field, Pfizer made a renewed push into obesity last year with its $10 billion acquisition of Metsera.
The company is making other metabolic medicine moves as well, and in February put up $495 million to gain exclusive commercialization rights to Sciwind Biosciences’ GLP-1 ecnoglutide, which recently won an approval in China.
