Metsera has reported encouraging results from its Phase 2 trials with the injectable obesity drug MET-097i, delivering a key milestone just days after Pfizer announced plans to acquire the biotech for $4.9 billion. Findings from the VESPER-1 study show that monthly doses of MET-097i resulted in an average placebo-adjusted weight reduction of 14.1% over 28 weeks, with some participants losing over 26% of their body weight. Analysts note these outcomes position Metsera’s candidate as a competitive rival to approved agents like Eli Lilly’s Zepbound and Novo Nordisk’s Wegovy, especially given the drug’s promising tolerability profile and potential convenience of once-monthly administration.
The study also found that MET-097i was well-tolerated, with notably fewer gastrointestinal side effects than typically seen with other GLP-1 class obesity drugs. Only 2 of the 239 trial volunteers discontinued due to adverse effects. An exploratory analysis at 36 weeks suggested that weight loss continued steadily without reaching a plateau, and additional results from alternative dosing regimens are expected later this year.
Pfizer’s acquisition of Metsera—unanimously approved by both companies’ boards—adds advanced oral and injectable metabolic therapies to Pfizer’s pipeline, signaling the pharma giant’s intent to regain ground in this lucrative sector following setbacks for its internal obesity candidates. Analysts predict that Metsera’s assets could generate billions if their efficacy holds in larger clinical studies, with global sales for new obesity treatments projected to top $150 billion by 2031. With Phase 3 trials slated to begin by the end of this year, all eyes are on Pfizer’s next steps as it embarks on one of 2025’s most watched biopharma deals.
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