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Pfizer‘s newest bet on obesity is already showing promise.
The company last week said it would buy weight loss drugmaker Metsera in an up to $7.3 billion deal, including future payments, that is expected to close at the end of the year. Just a week later, Metsera released data from mid-stage trials on its lead obesity drug candidate that will allow the company to start phase three studies on the treatment later this year.
Metsera, founded in 2022, brings a pipeline of both oral and injectable treatments with different targets. The company picked up those drugs through its own licensing and acquisition deals. But all eyes are on Metsera’s injection, MET-097i, which is the furthest along in development.
The company is developing the injection to be taken once a month, which could offer a convenient edge over the weekly injections currently dominating the market. MET-097i is in the GLP-1 class, which is the same category as Novo Nordisk‘s obesity drug Wegovy and Eli Lilly‘s rival treatment Zepbound.
Early data suggest it can deliver strong weight loss with fewer gastrointestinal side effects than the treatments on the market. The new data on Monday appears to back that up – at least for now.
In a note Monday, JPMorgan analyst Chris Schott said, “more broadly, we continue to see MET-097i as one of several emerging competitors that we believe will take some share” from Eli Lilly and Novo Nordisk over time. He called the results “solid,” adding that the drug’s overall profile looks in line with Eli Lilly’s weight loss drug Zepbound.
Let’s break down the results.
How much weight did patients lose?
Metsera said the highest dose of its injection demonstrated weight loss of up to 14.1% on average after 28 weekly doses in a mid-stage trial called VESPER-1. Some participants lost much more, with the highest being 26.5% weight loss.
VESPER-1 has an ongoing extension study that includes less frequent dosing options. Metsera said an exploratory analysis at the end of the weekly dosing phase of the extension at 36 weeks demonstrated “substantial and continued weight loss,” meaning that no plateau had happened.
It’s difficult to compare the results to those of other drugs without head-to-head studies, but the weight loss caused by Metsera’s injection appears to be encouraging. Wegovy caused around 15% weight loss after 68 weeks in larger phase three trials. Zepbound has shown weight loss above 20% in late-stage studies.
The other trial, VESPER-3, is ongoing, so Metsera did not report weight loss data on Monday. That trial is examining monthly dosing of the injection, with initial weight loss data expected by year-end or early 2026, according to the company. The drug has a long half-life – or the time it takes for the concentration of the drug in your body to reduce by half – which makes once-a-month dosing possible.
How well did patients tolerate the drug?
Patients appeared to handle Metsera’s injection well in both studies, based on existing data. But we still need more detailed data from the trials to say whether it can be tolerated better than the injections on the market, while also offering competitive weight loss.
The company said at a starting dose of 0.4 milligrams, its injection was as well tolerated as a placebo across both trials. Metsera said gradual, one-to-two step increases in that dose could give the drug a tolerability edge over rivals in the GLP-1 class.
In VESPER-3, patients who gradually increased their dose to the highest dose – 1.2 milligrams – over 12 weeks saw “little diarrhea, with only modest increases in nausea and vomiting.” Rates of nausea and vomiting among those patients were 13% and 11% above placebo, respectively.
Even at higher doses without a gradual ramp-up, the injection’s side effects in VESPER-1 were comparable to other approved weight-loss drugs, according to Metsera.
Notably, only 2.9% of patients in that trial – two out of 239 patients – stopped treatment due to side effects. While it’s only a mid-stage study, that discontinuation rate is encouraging.
Other obesity drugs in development have reported discontinuation rates nearing 10%, which is slightly above that of the existing treatments on the market.
Overall, we still want to see late-stage trials on MET-097i and Metsera’s other drugs. If everything goes as planned, the company’s pipeline could deliver sizable returns for Pfizer down the line.
In a note last week, Leerink Partners analyst David Risinger said the firm estimates Metsera’s obesity candidates have the potential to generate more than $5 billion in combined peak annual sales.
We’ll be sure to cover them closely, so stay tuned.
Feel free to send any tips, suggestions, story ideas and data to Annika at a new email: annika.constantino@versantmedia.com.
Latest in health-care: A high stakes Medicare open enrollment
Health insurers are prioritizing profitability over growth in Medicare Advantage for 2026, after grappling with higher-than-expected member health costs and regulatory reimbursement shifts which have eaten away at margins.
The Centers for Medicare & Medicaid Services projects that the pullback in some plan offerings could result in a decline in Medicare Advantage (MA) membership next year. It would be the first decline in more than a decade. Still, the agency says the market remains stable and plan offerings are robust.
But Medicare brokers who help seniors enroll in plans say this could be one of the most disruptive enrollment periods in more than a decade. Insurers are prioritizing plans with more restrictive provider networks, eliminating commissions on less profitable plans altogether. Analysts at Baird calculate that more than 70% of those so-called decommissioned plans are PPOs, or wider-network preferred provider organization plans.
The large players have telegraphed a lot of these strategies over the last few months. However, analysts say regional insurers are making some of the same moves, and that could prove to be the wild card in the mix.
“The potential for Regionals to exit MA in meaningful numbers raises the stakes for national MA plans this year, given an elevated risk of mispricing leading to unanticipated growth,” wrote Evercore ISI’s Elizabeth Anderson in a note to clients Tuesday morning.
The looming government shutdown on Wednesday is another unknown, though a former CMS official says it should not disrupt the open enrollment period because funding for the contractors involved in the process would already have been allocated.
Seniors can get their first look at new 2026 plans starting on Wednesday, ahead of the actual start of open enrollment Oct. 15.
Feel free to send any tips, suggestions, story ideas and data to Bertha at a new email: bertha.coombs@versantmedia.com.
