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Blackstone to fund up to $1.5 billion of Pfizer's monthly obesity drug trials

Blackstone to fund up to $1.5 billion of Pfizer's monthly obesity drug trials

Money Moves

The co-funding deal covers as many as 10 Phase 3 trials of berobenatide through 2028. Pfizer keeps control of the program and gives up no ownership.

3 days ago: Blackstone to fund up to $1.5 billion of berobenatide trials

Overview

Updated 1 hour ago

Pfizer has agreed to let Blackstone Life Sciences pay up to $1.5 billion of the development costs for berobenatide, an experimental weight-loss drug injected once a month. The money covers as many as 10 Phase 3 trials through 2028. Pfizer keeps full control of the program and gives up no ownership of the drug.

The arrangement moves part of the risk of late-stage testing onto a private equity firm. Blackstone gets milestone payments if U.S. regulators approve monthly dosing for chronic weight management and if sales reach certain targets. Pfizer gets cash to spend elsewhere while it faces generic competition for top sellers Eliquis and Ibrance.

Why it matters

A once-monthly GLP-1 shot would be the first of its kind, and Pfizer is now sharing that bet's cost with private equity.

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Key Indicators

$1.5B
Blackstone's maximum funding commitment
Development costs for berobenatide paid through 2028.
10
Phase 3 trials ongoing or planned
Covers chronic weight management plus knee osteoarthritis and sleep apnea.
15.9%
Weight loss at 60 weeks, weekly dosing
Phase 2b VESPER-1 result presented at the 2026 ADA congress.
12.4%
Weight loss at week 28, monthly dosing
Phase 2b VESPER-3 result for the once-monthly formulation.
$10B
Price Pfizer paid for Metsera
Winning offer after a bidding war with Novo Nordisk, up from an initial $4.9 billion bid.
20+
Obesity and comorbidity trials planned for 2026
Pfizer's stated plan across berobenatide and related peptides.

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People Involved

CG
Cecile Guegan
Chief financial officer and executive vice president, Pfizer
In office
NG
Nicholas Galakatos
Global head, Blackstone Life Sciences
In office
 David Risinger
David Risinger
Analyst, Leerink Partners
Covering Pfizer

Organizations Involved

Pfizer Inc.
Pfizer Inc.
Global pharmaceutical company
Sponsor and sole controller of the berobenatide program

New York-based drugmaker funding a monthly GLP-1 obesity shot it acquired with Metsera.
BL
Blackstone Life Sciences
Private equity investor
Paying up to $1.5 billion of berobenatide development costs

The life-sciences arm of Blackstone, which funds late-stage drug programs for milestone payments.
Metsera
Metsera
Biotechnology company
Acquired by Pfizer in November 2025

The startup whose metabolic drug portfolio included berobenatide, formerly MET-097.
U.S. Food and Drug Administration
U.S. Food and Drug Administration
Federal regulator
Would review any berobenatide marketing application

The agency whose approval of monthly dosing triggers Blackstone's milestone payments.
Novo Nordisk
Novo Nordisk
Pharmaceutical company
Competitor; lost the Metsera bidding war

Maker of the once-weekly obesity drug Wegovy and a rival bidder for Metsera.
Eli Lilly and Company
Eli Lilly and Company
Pharmaceutical company
Competitor in obesity drugs

Maker of the once-weekly obesity drug Zepbound and a potential head-to-head comparator.

Timeline

April 2023 November 2026

4 events Latest: 3 days ago
Tap a bar to jump to that date

  1. Blackstone to fund up to $1.5 billion of berobenatide trials

    Latest Deal

    Blackstone-managed funds will pay development costs through 2028 in exchange for milestone payments tied to FDA approval and sales.

  2. Phase 2b data show monthly dosing works

    Clinical data

    VESPER-1 showed 15.9% weight loss at 60 weeks with weekly dosing; VESPER-3 showed 12.4% at week 28 with monthly dosing.

  3. Pfizer wins Metsera with roughly $10 billion offer

    Acquisition

    Pfizer raised its bid from $4.9 billion to beat Novo Nordisk, gaining berobenatide and other metabolic drugs.

  4. Pfizer and Blackstone sign first co-funding deal

    Deal

    Blackstone agreed to provide up to $550 million toward development costs for certain Pfizer treatments.

Scenarios

1

Phase 3 confirms monthly dosing and Pfizer files for approval

Possible Resolves by End of 2028

Discussed by: Pfizer's stated development plan and analyst coverage of the program

The 10 Phase 3 trials read out with weight loss that supports once-monthly use, and Pfizer submits a U.S. marketing application for berobenatide as a single agent. That submission is the trigger for Blackstone's first milestone payment.

2

Monthly arm disappoints and Pfizer pursues weekly dosing only

Unlikely Resolves by End of 2028

Discussed by: BioPharma Dive reporting on the trial design and dosing comparisons

Monthly dosing trails the weekly formulation by enough that regulators or Pfizer's own team favor the once-weekly version. Blackstone's milestones are tied specifically to monthly dosing, so this outcome would leave the funding arrangement without its payout trigger.

3

Pfizer registers a head-to-head trial against Zepbound or Wegovy

Possible Resolves by End of 2027

Discussed by: BioPharma Dive, citing the commercial logic of comparator studies

Pfizer adds a Phase 3 study that tests berobenatide directly against Eli Lilly's Zepbound or Novo Nordisk's Wegovy. A win would strengthen pricing and formulary positioning; the trial would also add years and cost to the program.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

April 2023

Pfizer's first Blackstone co-funding deal (2023)

Pfizer and Blackstone signed an agreement under which Blackstone provided up to $550 million toward development costs for certain Pfizer treatments. The structure was the same as the 2026 deal: Blackstone pays for research, Pfizer keeps the assets.

Then

Pfizer spread part of its development spending to an outside investor without giving up drug rights.

Now

The arrangement became the template for the far larger berobenatide agreement three years later.

Why this matters now

The 2026 deal is roughly triple the size of the 2023 one, using the same mechanism on a single late-stage asset.

November 2025

The Metsera bidding war (2025)

Pfizer opened with a $4.9 billion bid for Metsera and its metabolic drug portfolio. Novo Nordisk counterbid, and Pfizer eventually won with an offer of about $10 billion, more than double its first price.

Then

Pfizer paid a steep premium for a monthly GLP-1 candidate after its own oral obesity drugs failed on safety.

Now

The price raised the pressure to run a broad, expensive Phase 3 program, which is what the Blackstone money now funds.

Why this matters now

The size of the Metsera check explains why Pfizer wants a partner to carry part of the trial costs.

Sources

(5)
BioPharma Dive Pfizer Reuters pharmaphorum Axios