Pfizer's Obesity Drug Trial Shows Up to 12.3% Weight Loss

Pfizer Inc. announced promising midstage trial results for its experimental obesity drug on Tuesday, revealing up to 12.3 percent weight loss in patients without diabetes after 28 weeks of treatment. The data, released alongside the company's stronger-than-expected fourth-quarter earnings, highlighted the drug's potential as a monthly injection in a competitive market dominated by rivals like Eli Lilly and Novo Nordisk, though concerns over side effects contributed to a nearly 3 percent drop in Pfizer's shares during premarket trading.

The drug, known as PF-06954589 or PF3944, was acquired through Pfizer's $10 billion purchase of biotech firm Metsera in November, following a bidding war with Novo Nordisk. In the phase two trial, participants with obesity or overweight conditions began with weekly subcutaneous injections for 12 weeks before transitioning to monthly dosing. The study tested various doses to assess sustained weight loss and tolerability after the switch. Pfizer reported robust and continuous weight loss without a plateau at week 28, with the company anticipating further progress as the trial extends to week 64.

Across the trial arms, patients achieved an average...