Pfizer's $4.9B Metsera Acquisition Yields Promising Weight Loss Drug Results

Pfizer's recent $4.9 billion acquisition of Metsera is already showing signs of potential success, as the biotech company unveils impressive results for its lead GLP-1 agonist, MET-097i. The injectable candidate, central to Pfizer's obesity drug pipeline expansion, has demonstrated significant weight loss and tolerability in recent clinical trials.

MET-097i Shows Competitive Efficacy in Phase 2b Trials

The phase 2b Vesper-1 study, evaluating weekly dosing of MET-097i, reported a mean placebo-subtracted weight loss of 14.1% after 28 weeks for patients receiving the highest 1.2-mg dose. This result outperforms previous data from trials of Novo Nordisk's semaglutide (Wegovy), which showed 9.6% and 12% weight loss at the same time point in separate studies.

Metsera's Chief Medical Officer, Steve Marso, M.D., emphasized the potential of MET-097i, stating that these "excellent results" confirm its ability to deliver "competitive efficacy with category-leading scalability, tolerability, and convenience."

Tolerability Profile Positions MET-097i as a Strong Competitor

Alongside its efficacy, MET-097i's tolerability profile is garnering attention. In the Vesper-3 study, which evaluated monthly dosing options, patients who titrated from 0.4 mg to 1.2 mg experienced minimal increased risk of diarrhea, with only a 13% risk difference from placebo for nausea and 11% for vomiting.

Notably, in the Vesper-1 study, only two of 239 participants discontinued treatment due to adverse events. This compares favorably to previous studies of semaglutide, where 4.5% of patients discontinued due to gastrointestinal events.

Future Prospects and Industry Impact

Based on these promising results, Metsera is advancing MET-097i into phase 3 clinical trials. The company expressed confidence that doses of MET-097i could match or exceed the performance of Eli Lilly's tirzepatide (Mounjaro) at steady state.

John Buse, M.D., Ph.D., a professor at the UNC School of Medicine, described the efficacy and tolerability of MET-097i as "remarkable," suggesting that it could be the first nutrient-stimulated hormone (NuSH) analog in late-stage clinical development poised to meet or exceed the high bar set by tirzepatide.

Pfizer's acquisition of Metsera, which also includes a monthly injectable amylin analog and an oral GLP-1 candidate, positions the pharmaceutical giant as a more credible threat in the competitive obesity treatment landscape. As the global phase 3 study of MET-097i is set to begin later this year, with 28-week data from the Vesper-3 study expected in late 2025 or early 2026, the industry eagerly awaits further developments in this rapidly evolving field.