Pfizer says obesity injection shows promise as monthly treatment in mid-stage trial

Pfizer says obesity injection shows promise as monthly treatment in mid-stage trial

Published Tue, Feb 3 2026

7:18 AM EST

Key Points

• Pfizer said its experimental obesity drug, which it acquired through Metsera, drove solid weight loss when taken once a month in a mid-stage trial.
• The data offer early evidence that the injection can be administered less frequently than existing drugs without sacrificing efficacy.

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Pfizer on Thursday said its experimental obesity drug, which it acquired through Metsera, drove solid weight loss when taken once a month in a mid-stage trial.

Patients with obesity or who are overweight lost up to 12.3% of their weight compared with placebo at week 28 in the ongoing phase two study. The injection's weight loss was up to 10.5% when analyzing all patients regardless of discontinuations.

The data offer early evidence that the injection can be administered less frequently than existing drugs without sacrificing efficacy, which could be a major boost for Pfizer. It's trying to enter a market dominated by Eli Lilly and Novo Nordisk's weekly injections, with a strong new entrant in Novo's daily pill.

Pfizer plans to advance 10 phase three trials on the injection, called PF'3944, this year.

"These topline results ... reinforce the potential of PF'3944 as a monthly treatment with competitive efficacy," said Dr. Jim List, Pfizer's chief internal medicine officer, in a release.

The trial randomized patients to gradually switch from weekly to monthly injections of Pfizer's treatment. No plateau was observed after patients transitioned to monthly dosing, the company said.

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