Pfizer starts the US Phase 3 trial of berobenatide

Pfizer has started enrolling participants in a Phase 3 clinical trial of berobenatide, an experimental weight-loss injection, in adults with overweight or obesity in the United States ^[1]. The trial, listed on ClinicalTrials.gov as NCT07595549, is targeting 954 participants, and its primary completion date is set for May 4, 2028 ^[1].

Berobenatide, also known by its development code PF-08653944, is being tested as a treatment for people with overweight or obesity ^[1]. The drug is part of Pfizer's effort to compete in the fast-growing market for GLP-1 medications, which currently includes semaglutide (sold as Ozempic, Wegovy, and Rybelsus) and tirzepatide (sold as Mounjaro and Zepbound) ^[1].

Separately, Pfizer has also registered Phase 3 studies of berobenatide in Japan. One study, called VESPER-JM, is testing once-monthly dosing in adults with obesity disease ^[2]. That trial, listed as NCT07794774, is examining the safety and effects of this less-frequent injection schedule ^[2]. The sources describe Pfizer as running both once-monthly and once-weekly Phase 3 programs in Japan, positioning berobenatide as a rival to MariTide, another drug being developed with less-frequent dosing in mind.

The US trial is a randomized study, though the sources do not specify the exact doses being tested or how they compare with existing approved drugs ^[1]. The Japan study also does not detail specific dose levels in the available material ^[2].

Why it matters for patients

Most approved GLP-1 drugs for weight management, including Wegovy and Zepbound, require weekly injections. A drug that works well with less frequent dosing, such as monthly, could mean fewer injections for patients who choose this type of treatment. That could matter for people who find weekly shots inconvenient or who have trouble sticking to a strict schedule.

However, it is not yet known whether berobenatide will prove as effective or as safe as existing treatments. The Phase 3 trial just started enrolling, and results are not expected until 2028 based on the primary completion date ^[1]. This means the drug is still years away from potential approval or use by patients in the United States.

The sources do not include information about berobenatide's mechanism of action, potential side effects, or how much weight loss might be expected. Patients interested in this drug will need to wait for trial results before more is known about its effectiveness and safety profile.

It is also not yet known how berobenatide might be priced or whether insurance would cover it, since those questions typically are not addressed until closer to approval.

What happens next

The US Phase 3 trial's primary completion date is set for May 4, 2028 ^[1]. This is the point at which the main results needed to evaluate the drug's effectiveness and safety are expected to be collected, though full study completion and any regulatory review would likely take longer.

The Japan-based once-monthly study, VESPER-JM, is also underway, though the sources do not provide a specific completion date ^[2]. Pfizer has also registered a once-weekly Phase 3 program in Japan, according to the development summary, though details of that trial are not included in the available source material.

Until these trials produce results, it remains unclear how berobenatide will compare with approved GLP-1 medications in terms of weight loss, side effects, and dosing convenience.