Metsera is the company Pfizer bought to get back into obesity drugs. Its portfolio was a weekly-or-monthly injectable GLP-1 drug and a monthly amylin drug when it was acquired by Pfizer in November 2025 after a short bidding contest with Novo Nordisk, the maker of Wegovy and Ozempic. Its lead drug now carries a generic name, berobenatide, and is in ten registered phase 3 trials. None has reported.
This page is built from documents that can be checked: Metsera's and Pfizer's filings with the US Securities and Exchange Commission, Pfizer's pipeline update, and the trial registry, all read on 20 October 2026. Deal figures are what the filings say; trial figures are what the registry posts. Nothing here is a forecast of approval or a statement about whether the drug works.
Why Pfizer needed a company to buy
Pfizer had its own GLP-1 pill, danuglipron (PF-06882961), in development for chronic weight management. Its pipeline document for April 2025, filed with the SEC, records: "Discontinued April 2025", following "a review of the totality of information, including all clinical data generated to date for danuglipron and recent input from regulators." Five months later Pfizer agreed to buy Metsera. Danuglipron's end is the context; the Metsera deal was the replacement, and the drug that now carries Pfizer's obesity hopes is Metsera's, not Pfizer's own.
The deal, from the filings
| Date | Event (source) |
|---|---|
| 22 Sep 2025 | Pfizer and Metsera announce a definitive agreement: $47.50 a share in cash plus a contingent value right of up to $22.50, an initial enterprise value of $4.9 billion (joint release, Metsera 8-K exhibit 99.1) |
| late Oct 2025 | Novo Nordisk makes an unsolicited competing proposal; Pfizer files suit against Metsera in the Delaware Court of Chancery, and Metsera states on 31 October that it "disagrees with the allegations" (Metsera 8-K exhibit) |
| 7 Nov 2025 | Amended Pfizer agreement: $65.60 cash plus a right worth up to $20.65, up to $86.25 a share; Metsera's board cites an FTC call about "potential risks from proceeding with the proposed Novo Nordisk structure under U.S. antitrust laws" (Metsera release, filed 10 Nov) |
| 13 Nov 2025 | Pfizer completes the merger; Metsera becomes a wholly owned subsidiary and is delisted from Nasdaq (Metsera and Pfizer 8-Ks) |
A contingent value right pays only if named milestones are reached, so "up to $86.25" is a ceiling, not the price paid. The cash element alone rose from $47.50 to $65.60 a share, a 38% increase, in seven weeks of competition — glp1ledger's arithmetic from the two filings.
What Pfizer bought
The September 2025 release describes the portfolio at the time of the agreement:
- MET-097i — "a weekly and monthly injectable GLP-1 receptor agonist", then in phase 2.
- MET-233i — "a monthly amylin analog candidate", in phase 1 alone and with MET-097i. Amylin is a pancreatic hormone; the amylin approach is the one also behind cagrilintide in Novo Nordisk's CagriSema, covered on CagriSema.
- Two oral GLP-1 candidates, then "expected to begin clinical trials imminently".
The drug class and how it works are on how GLP-1 works; MET-097i is a GLP-1 drug alone, not a dual agonist like tirzepatide.
One drug, three names
In the trial registry the lead drug appears as MET097 (Metsera's records), PF-08653944 (Pfizer's code) and, in records posted from 2026, berobenatide, its international non-proprietary name. Several Pfizer records use two of these at once — for example "Berobenatide (PF-08653944)". Anyone searching the registry for the drug's status needs all three; searching one name alone misses most of the trials.
The trials, counted
A ClinicalTrials.gov search on 20 October 2026 for any of the names, or for Metsera as sponsor, returned 21 studies. By phase:
| Phase | Studies | Status on 20 Oct 2026 |
|---|---|---|
| Phase 3 | 10 | 5 recruiting, 2 active and not recruiting, 3 not yet recruiting |
| Phase 2 / 2b | 4 | including VESPER-1 (completed, results posted) and SOLIS-1, an umbrella study with PF-08653945 |
| Phase 1 / 1-2 | 7 | pharmacology, kidney function, Chinese participants, and the MET-233i combination study |
The ten phase 3 records plan to enrol about 7,900 people in total (glp1ledger's sum of the registry's enrolment figures). The two largest:
- VESPER-4 (NCT07311850) — about 3,578 adults with overweight or obesity, weekly MET097 against placebo, primary measure percent weight change at 64 weeks; active, not recruiting.
- NCT07400653 — about 1,078 adults with obesity or overweight, PF-08653944 against placebo; active, not recruiting.
And the one that shows what Pfizer is aiming at: VESPER-SWITCH (NCT07845500), about 660 adults already on weekly semaglutide or tirzepatide who are moved to monthly berobenatide, with weight change at 32 weeks as the primary measure. A monthly injection that holds weight lost on a weekly one is a different product proposition from another weekly drug.
The one posted result
VESPER-1 (NCT06712836), a phase 2b trial of weekly MET097 in 239 adults with obesity, completed in April 2026 and has results posted on the registry. For Part A, the least-squares mean percent change in body weight at week 28 was:
| Weekly dose | Weight change at week 28 |
|---|---|
| 0.4 mg | -6.41% |
| 0.6 mg | -8.36% |
| 0.9 mg | -11.29% |
| 1.2 mg | -12.45% |
| Placebo | +1.67% (as posted) |
Registry results, standard errors 0.89 to 0.93. These are 28-week figures; the approved drugs' headline results are at 68 to 72 weeks, so the numbers are not comparable with Wegovy's or Zepbound's. The positive placebo figure is reported as the registry shows it. What a phase 2 result does and does not predict is the same as for every pipeline drug on this site: phase 3 is where the claim is tested.
Where it stands
- No approval, and no application announced in the sources read. Berobenatide is an investigational drug.
- No phase 3 result. The primary measures in the records read here fall at 32 weeks (VESPER-SWITCH) and 64 weeks (VESPER-4) after starts in 2025 and 2026.
- The term is past its news peak. Searches for "Metsera" fell sharply after the deal closed; the durable question is what Pfizer's GLP-1 drug is, which is the question this page answers.
The other drugs racing to follow Wegovy and Zepbound — orforglipron (Foundayo), retatrutide, survodutide, amycretin, MariTide and others — are compared on which drugs are GLP-1s, and the newest approved pill on Foundayo.
Sources
- Metsera, Inc. and Pfizer Inc., "Pfizer to Acquire Metsera and its Next-Generation Obesity Portfolio", 22 September 2025, Metsera Form 8-K exhibit 99.1, SEC accession 0001193125-25-210030.
- Metsera, Inc., "Metsera Issues Statement in Response to Litigation", 31 October 2025, Form 8-K exhibit 99.1, SEC accession 0001193125-25-261203.
- Metsera, Inc., "Pfizer and Metsera Enter into Merger Agreement Amendment", 7 November 2025, Form 8-K exhibit 99.1, SEC accession 0001193125-25-273292.
- Metsera, Inc., Form 8-K reporting completion of the merger, 13 November 2025, SEC accession 0001193125-25-280387.
- Pfizer Inc., pipeline update filed as Form 8-K exhibit 99, 29 April 2025 (danuglipron entry), SEC accession 0000078003-25-000111.
- ClinicalTrials.gov API v2, search for MET-097i, MET-233i, Metsera, PF-08653944 and berobenatide, and records NCT06712836 (posted results), NCT07311850, NCT07845500, NCT07575932 — read 2026-10-20.