Pfizer company logo is seen at a Pfizer office in Puurs, Belgium, December 2, 2022. REUTERS/Johanna Geron

By Kamal Choudhury and Mariam Sunny

(Reuters) -Pfizer on Thursday closed its up to $10 billion acquisition of Metsera after winning shareholder approval, gaining a foothold in the fast-growing obesity market following a fierce bidding war with Novo Nordisk.

The greenlight from Metsera's shareholders paves the way for Pfizer to diversify beyond its shrinking COVID-19 portfolio, navigate looming patent expirations, and tap into the fast-growing weight-loss drug market that analysts estimate could be worth $150 billion annually by the end of the decade.

Shares of Pfizer were up 1.4%, while U.S.-listed shares of Novo slipped 1.3%.

"By acquiring Metsera, we are directing our resources toward one of the most impactful and high-growth therapeutic areas and positioning ourselves to define it," Pfizer CEO Albert Bourla said in a statement.

Pfizer had discontinued two oral GLP-1 candidates - lotiglipron in 2023 and danuglipron in 2025 - due to liver safety concerns, leaving it without a viable in-house obesity drug.

Metsera's board had unanimously backed Pfizer's amended offer, which valued the biotech at up to $86.25 per share, including $65.60 in cash and up to $20.65 tied to success of its drug pipeline.

Metsera's lead candidate, MET-097i, a once-monthly GLP-1 injection, has drawn attention for its potential to rival Novo's Wegovy and Eli Lilly's Zepbound, which require weekly injections.

MET-097i had helped patients lose up to 14.1% of their body weight in two mid-stage studies. The company is advancing it into late-stage trials.

Pfizer said in September it expects Metsera's drugs to launch in the 2028, 2029 time frame and potentially help offset upcoming patent losses.

Earlier this year, Pfizer said it expects a $17 billion to $18 billion revenue hit annually from drugs losing patent protection between 2026 and 2028, including blood thinner Eliquis and cancer drugs Ibrance and Xtandi.

(Reporting by Kamal Choudhury and Mariam Sunny in Bengaluru; Editing by Maju Samuel)