In November 2025, Pfizer finalized its $10 billion acquisition of Metsera, a transaction that highlighted the company’s strategic push into the rapidly expanding obesity treatment market. The acquisition follows a decline in Pfizer’s COVID-19–related profits, which fell from $17.7 billion to $16.65 billion by the third quarter of 2025, highlighting the need to strengthen its growth pipeline as pandemic-driven revenues continue to diminish.
The deal comes at a pivotal moment for the pharmaceutical giant. With several key patents set to expire by 2026, Pfizer faces increasing pressure to broaden and diversify its internal medicine portfolio (see ParolaNEWS article: Pfizer’s impending patent cliff). By securing Metsera’s obesity-focused assets, Pfizer strengthens its position in the anti-obesity segment, a market that reached an estimated $30 billion in global spending in 2024.
Why Metsera?
Founded in 2022, Metsera is a clinical-stage biotechnology firm based in New York City, that specializes in developing treatments for obesity and metabolic diseases. The company has built a focused pipeline of innovative drug candidates designed to meet the growing demand for effective and accessible anti-obesity treatments.
Among its leading programs is MET-097i, a potent injectable GLP-1 receptor agonist formulated for monthly dosing. Its Phase 2B trial demonstrated an average 14.1% weight loss, effectively advancing it into Phase 3 development. Metsera is also developing MET-233i, a monthly injectable amylin analog being evaluated both as a standalone therapy and in combination with MET-097i.
In addition, Metsera is also advancing oral GLP-1 receptor agonists, including MET-224o and MET-097o, which are still in Phase 1 trials. These candidates are designed to offer the benefits of GLP-1–based treatment in a more convenient pill form at lower doses.
Breach of contract and antitrust lawsuits
Before the transaction was completed, Pfizer initiated two lawsuits against Metsera concerning disputes arising from the acquisition process. The legal actions followed the execution of a $4.9 billion merger agreement in September 2025, under which Metsera was required to conduct the transaction in strict accordance with the agreement’s terms, including provisions governing the evaluation of, or engagement with, competing acquisition proposals.
Pfizer filed its first lawsuit on October 31 in the Delaware Court of Chancery, alleging that Metsera had breached both the merger agreement and its fiduciary duties by improperly considering a competing bid from Novo Nordisk. The complaint contended that designating Novo Nordisk’s offer as a “Superior Company Proposal” violated the merger agreement, arguing that the proposal was not reasonably likely to be completed due to significant regulatory risks. Pfizer sought to prevent Metsera from terminating the merger agreement, though the Court of Chancery later denied the request.
The dispute escalated on November 3, when Pfizer filed a second lawsuit in U.S. federal court, raising antitrust objections to Novo Nordisk’s proposed acquisition. Pfizer argued that the transaction could substantially reduce competition in the GLP-1 obesity drug market, potentially resulting in monopolistic control over a sector affecting millions of patients. The complaint alleged violations of Section 7 of the Clayton Act and Sections 1 and 2 of the Sherman Act, asserting that the deal would unlawfully restrain trade and constitute an attempt to monopolize the market.
The patents behind Pfizer’s obesity drugs
Over the years, Pfizer has secured patents on obesity and metabolic disease therapies, focusing on GLP-1 receptor agonists and related combination approaches. These filings protect its drug candidates and support its strategy to expand in obesity and type 2 diabetes treatment.
Next-generation GLP-1 receptor agonists for metabolic health
As of 2024, approximately 589 million people worldwide are diagnosed with diabetes, with around 90% of cases classified as type 2. This number is projected to reach 853 million by 2050, effectively highlighting the urgent need for effective and accessible treatments for diabetes and related metabolic disorders. At the same time, global obesity rates have also soared, which further adds to the growing burden of metabolic health challenges.
Despite these, most current therapies for type 2 diabetes and obesity have significant limitations. Some medications can lose effectiveness over time or cause side effects such as weight gain or low blood sugar, while the most effective GLP-1–based treatments are injectable peptides, which can be inconvenient and difficult for patients to use consistently in the long term.
To address this problem, U.S. Patent No. 10,676,465 introduces a small-molecule GLP-1 receptor agonist that provides the therapeutic benefits of GLP-1 therapy without relying on injections. Designed for oral delivery, these compounds offer simpler, more patient-friendly options to regulate glucose, support insulin function, and manage metabolic conditions.
While this patent describes a broader family of small molecules, U.S. Pat. No. 2023/0201185 specifically describes Danuglipron (PF‑06882961), an orally deliverable GLP-1 receptor agonist optimized for treating type 2 diabetes, obesity, or overweight. Together, these innovations highlight the development of oral, non-peptide GLP-1 therapies that improve patient convenience and support sustained management of diabetes and obesity.
The patent, titled “GLP-1 receptor agonists and uses thereof”, was filed on August 8, 2019, and granted on June 9, 2020. The patent lists Gary Aspnes, Scott Bagley, John Curto, David Edmonds, Mark Flanagan, Kentaro Futatsugi, David Griffith, Kim Huard, Yajing Lian, Chris Limberaki, Allyn Londregan, Alan Mathiowetz, David Piotrowski, and Roger Ruggeri as inventors.
Dual-pathway therapy for obesity and diabetes
Metabolic diseases involve a complex interplay of hormones that regulate appetite, fat storage, and blood glucose. While GLP-1–based therapies improve insulin function and appetite control, they address only part of this network, leaving other pathways to drive fat accumulation, insulin resistance, and related complications. As a result, relying solely on GLP-1 receptor activation leaves gaps in treatment and limits overall effectiveness for weight management, metabolic regulation, and the prevention of obesity-related comorbidities.
U.S. Pat. App. Pub. No. 2025/0235510 addresses these limitations by introducing a combination approach that pairs a GLP-1 receptor agonist with a glucose-dependent insulinotropic polypeptide (GIP) receptor antagonist. By activating GLP-1 pathways while suppressing GIP signaling, this therapy aims to improve glucose regulation, enhance insulin sensitivity, suppress appetite, and reduce fat accumulation. The patent also outlines formulations and administration strategies for these dual agents, offering a more comprehensive approach to treating obesity, type 2 diabetes, and related metabolic disorders than single-pathway therapies alone.
The patent application, titled “Combination therapy using glucose-dependent insulinotropic polypeptide receptor antagonist compounds and glp-1 receptor agonist peptides”, was filed on January 23, 2025. The patent lists Robert Dullea, Kevin Filipski, and Matthew Sammons as inventors.
Pfizer’s Obesity Portfolio: Patenting Activity
Following the approval of Saxenda® in December 2014 as the first GLP-1 receptor agonist for weight management, pharmaceutical companies began advancing their GLP-1 programs beyond diabetes care toward therapies specifically aimed at weight loss.
Pfizer followed the same trend and maintained high levels of obesity-related patenting activity from 2015 to 2020, reflecting the company’s efforts to establish a position in the emerging obesity treatment market. By 2021, Pfizer’s patent filings on obesity treatment declined, coinciding with the company’s heightened focus on COVID-19 research. which temporarily slowed the progress in its obesity pipeline.
Looking ahead
Pfizer continues to strengthen its presence in the obesity drug market through its recent collaboration with YaoPharma. Under this agreement, the company will gain global rights to develop and commercialize YaoPharma’s YP05002, the company’s oral GLP-1 pill, as it advances through early clinical trials.
The partnership reflects a strategic push into innovative weight‑management treatments, including potential combination therapies with other molecules in Pfizer’s pipeline such as the GIP receptor antagonist PF-07976016, currently in Phase 2 development. This approach positions the company to expand its metabolic disease portfolio and compete more broadly in the growing obesity market.
