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Pfizer’s experimental drug shows up to 12.3% weight loss in mid-stage trial

By Thomson Reuters Feb 3, 2026 | 5:45 AM

Feb 3 (Reuters) – Pfizer said on Tuesday its experimental obesity drug, which it acquired ‍through the Metsera deal, showed up to 12.3% weight loss in patients without diabetes in a mid-stage trial.

In November, Pfizer acquired ‌Metsera for up to $10 billion ‌following a fierce bidding war with Novo Nordisk.

The mid-stage trial was studying the monthly maintenance dosing of the ​drug, PF’3944, to see if it could achieve continued ‍weight loss when ​switching from weekly to ​monthly injections under the skin.

These ‍data show robust and continuous weight loss after switching to monthly dosing, with no plateau observed at week 28, the ‍company said, adding that it expects the trend to continue as the ‍study ‍reaches week 64.

Across both ​arms, five total participants ​discontinued ⁠from treatment due to ‌side effects in the weekly phase and five total participants discontinued in the monthly phase.

(Reporting by Sriparna Roy in Bengaluru; Editing by ⁠Leroy Leo)