Blackstone injects $1.5bn into Pfizer obesity drug development

Pfizer has secured $1.5bn in funding from Blackstone Life Sciences to accelerate the clinical development of berobenatide, a monthly glucagon-like peptide-1 receptor agonist. The private equity firm will cover the development costs of the asset through 2028, allowing the pharmaceutical company to advance its weight loss programme without immediate financial strain. In return for the investment, Blackstone is eligible for milestone-based payments contingent on the drug reaching the US market and achieving specific sales targets, although the deal does not confer any ownership rights to the medication.

Berobenatide, formerly known as MET097i, is central to Pfizer’s strategy to enter the obesity market. The asset was acquired as part of the $10bn takeover of Metsera in December 2025, a transaction that concluded after a competitive bidding process involving Novo. Pfizer maintains an extensive clinical programme for the drug, which includes 10 ongoing or planned Phase III studies. These trials evaluate berobenatide for chronic weight management as well as obesity-related comorbidities, including knee osteoarthritis and obstructive sleep apnoea. The company has previously trimmed other parts of its obesity pipeline, but this asset remains a priority.

Cecile Guegan, Pfizer’s chief financial officer, stated that the announcement supports the advancement of the company’s comprehensive obesity programme while preserving financial flexibility for broader pipeline investments. Citi analysts noted in a research report that the transaction improves the risk-adjusted economics of the programme. They highlighted that differentiation in efficacy, tolerability, and monthly dosing remains the key value driver for the asset.

The move positions Pfizer to compete in a market currently dominated by Eli Lilly. In the third quarter, Lilly’s tirzepatide brands, Mounjaro and Zepbound, generated global sales of $10.7bn and $5.4bn respectively. This combined quarterly revenue of approximately $16.1bn exceeded the total revenue of several other major pharmaceutical companies, including Novartis, GSK, and Bristol Myers Squibb. Novo also maintains a significant market share with its semaglutide franchise, which now includes a daily pill. While Novo has prioritised the US, Europe, and the UK for its Wegovy pill launch, Lilly is leveraging the administration of its Foundayo pill to close the gap, having secured approval in China before other territories.