The Pharma giant Pfizer has secured up to $1.5 billion from Blackstone Life Sciences to accelerate the development of berobenatide, an experimental monthly injection for obesity and chronic weight management. The Pfizer and Blackstone obesity drug deal will fund clinical development costs through 2028, while allowing Pfizer to retain full ownership and control of the medicine.
Under the Pfizer and Blackstone funding agreement, Blackstone will receive milestone-based payments if berobenatide drug achieves US regulatory approval for monthly injectable use as a standalone treatment and meets specified commercial sales targets. The partnership gives Pfizer additional financial flexibility as it expands its obesity drug pipeline and competes in the growing weight-loss treatment market.
How Is the Pfizer and Blackstone Obesity Drug Deal Structured?
The $1.5 billion Pfizer and Blackstone obesity drug deal follows a co-funding model in which Blackstone supports research and development costs rather than purchasing a stake in the medicine.
The Pfizer and Blackstone funding agreement includes the following terms:
- Development funding: Blackstone will cover eligible development costs of up to $1.5 billion through 2028.
- Milestone payments: Blackstone may receive payments over several years if the drug meets the agreed regulatory and commercial milestones.
- Ownership: Pfizer retains full ownership of berobenatide and controls its clinical development and operational decisions.
- Investment structure: Funds managed by Blackstone Life Sciences will invest alongside funds from Blackstone’s perpetual private equity strategy, known as BXPE.
The companies have not disclosed the potential milestone payment amounts.
Cecile Guegan, Pfizer’s Chief Financial Officer, said the agreement would help the company “maintain the financial capacity and flexibility to invest in our broader pipeline across all therapeutic areas.”
Earlier, in April 2023, Pfizer entered another funding agreement with Blackstone worth up to $550 million to support development costs for certain treatments.
What Is Pfizer’s Monthly GLP-1 Obesity Drug Berobenatide?
Berobenatide (PF-3944/MET-097i) is an investigational GLP-1 receptor agonist peptide that Pfizer is developing as a chronic weight management drug.
GLP-1 receptor agonists are medicines that mimic the action of a natural gut hormone involved in appetite regulation and blood sugar control. These medicines can help people feel fuller and reduce food intake.
Unlike several existing injectable obesity treatments that require more frequent administration, Pfizer is investigating berobenatide as a potential first-in-class monthly GLP-1 injection.
Pfizer is studying the Berobenatide GLP-1 drug for:
- Chronic weight management in people with obesity.
- Obesity-related knee osteoarthritis, a condition that affects the joints.
- Obstructive sleep apnea, a sleep disorder that causes repeated interruptions in breathing.
Pfizer is also exploring berobenatide drug as a standalone treatment and in combination with other nutrient-stimulated hormone (NuSH) peptides, including amylin analogues. These combinations could help expand its approach to obesity treatment development.
What Results Did The Pfizer Clinical Trials Show?
The Pfizer and Blackstone obesity drug deal comes as the pharmaceutical company expands its clinical research programme.
Pfizer plans to advance more than 20 clinical trials for obesity and related conditions in 2026. This includes 10 ongoing and planned Phase 3 trials for berobenatide.
Earlier berobenatide clinical findings have also provided insights into its potential.
At the American Diabetes Association’s 2026 Scientific Sessions, Pfizer presented Phase 2b results from its VESPER studies. In the VESPER-1 extension, participants who continued berobenatide treatment beyond week 28 maintained weight loss of 10.3% to 14.9% through week 60, depending on the monthly dose.
The monthly dosing approach could also offer a different administration schedule from existing treatments. However, its potential advantages will depend on further clinical evidence and regulatory assessment.
These findings support further investigation of the GLP-1 treatment, although clinical trial results do not guarantee regulatory approval or future outcomes for patients.
Why the Pfizer Metsera Acquisition Makes This Deal Important?
The Pfizer and Blackstone funding agreement also strengthens its efforts in position in the competitive obesity treatment market.
Pfizer acquired Metsera in 2025 in a transaction valued at up to $10 billion, bringing berobenatide into its drug development portfolio. The acquisition formed part of the company’s broader strategy to strengthen its business as revenue from some established products faces pressure from patent expirations.
Pfizer currently has no approved GLP-1 medicine specifically for weight loss on the market. Developing berobenatide could therefore provide an opportunity to enter a market dominated by established pharmaceutical companies, including Novo Nordisk and Eli Lilly.
What’s Next in Berobenatide Weight Loss Drug Development?
Pfizer and Blackstone obesity drug deal will support Pfizer’s clinical development programme through 2028. The company must continue evaluating berobenatide’s safety and effectiveness before seeking regulatory approval.
The US Food and Drug Administration (FDA) will need to assess the clinical evidence before deciding whether the medicine can enter the market.
For now, berobenatide remains an investigational treatment, with no confirmed commercial launch date.
