Pfizer reported mid-stage VESPER-3 data showing berobenatide caused vomiting in 23.3% of patients and nausea in about 38%, roughly in line with Wegovy trial rates.
The company said gastrointestinal side effects were mostly mild, concentrated around early doses and the injection window, which it linked to the drug's long half-life and monthly dosing pattern.
Researchers also saw adverse events rise when patients switched from weekly to monthly dosing, prompting Pfizer to plan a more gradual dose escalation in late-stage trials.
Berobenatide had already shown up to 12.3% weight loss in patients without diabetes, and Pfizer is betting monthly dosing can improve adherence versus weekly obesity shots.
The drug is central to Pfizer's obesity push after its $10 billion Metsera acquisition, following the discontinuation of two in-house weight-loss candidates over liver safety concerns.
Is a monthly weight loss shot's convenience worth the risk of month-long side effects?
With monthly shots and daily pills arriving, who will win the billion-dollar war on obesity?
Will your DNA soon decide which weight loss injection is right for you?
Monthly Obesity Treatments Advance: Amgen and Pfizer Lead the Shift Beyond Weekly GLP-1s
Overview
The obesity treatment market, once dominated by weekly GLP-1 agonists like Wegovy and Zepbound, is rapidly evolving with the introduction of new oral GLP-1 pills that are attracting new patients and expanding access, especially for seniors on Medicare. At the same time, significant progress is being made in developing therapies with longer dosing intervals, such as monthly or less frequent injections. Pfizer, after a previous setback, has renewed its efforts in obesity treatment, signaling a shift toward more convenient options. These advancements are reshaping the market, offering greater convenience and potentially improving patient adherence.