Amgen's experimental drug MariTide helped overweight or obese patients shed up to 20% weight on average in a year-long mid-stage trial, although its shares tumbled 12% on Tuesday after the data failed to meet lofty investor expectations.
Wall Street analysts said the weight-loss benefit was in line with the already approved drugs from Novo Nordisk and Eli Lilly, along with slightly higher side effects.
Data showed about 11% of patients on Amgen's drug discontinued due to adverse events in the dose escalation arms of the study. That compares with 4-7% discontinuation due to side effects from Lilly's drug during trials, according to Jefferies analyst Michael Yee.
There would be some investor disappointment over the 20% weight loss and a worse side-effect profile, Yee said.
Shares of the drugmaker were on track for their biggest percentage fall in more than two decades, potentially erasing more than $16 billion from the Dow component's market value.
Still, Amgen is betting on the drug as it offers a more convenient dosing option over existing treatments.
It also plans to test a quarterly dose of the drug, which was administered monthly or once every other month in the study, compared with weekly injections offered by Novo's Wegovy and Lilly's Zepbound.
"Certainly, it's more convenient to have a monthly injection rather than having a weekly injection, 52 injections over the time period," Amgen executive Susan Sweeney said.
Amgen also said patients generally experienced side effects after the first dose and then may go another 51 weeks without any events of nausea and vomiting.
The company also did not disclose details about weight loss linked to the dose amount, which analysts were expecting.
The 592-patient study involved a complicated design that tested several doses of the drug in overweight and obese people both with and without diabetes.
Amgen is betting on MariTide's unique approach and less frequent dosing to grab a slice of the potential $150 billion obesity treatment market, dominated by Wegovy and Zepbound.
MariTide is an antibody linked to a pair of peptides that activates the GLP-1 receptor while simultaneously blocking the GIP receptor. Amgen plans to assess a quarterly dosing in the next part of the study.
Wegovy targets receptors for the appetite- and blood sugar-reducing hormone known as GLP-1, while Lilly's Zepbound stimulates GLP-1 and a second gut hormone called GIP.
The common side effects for trial patients were gastrointestinal, including nausea, vomiting and constipation. Nausea and vomiting were mostly mild, transient and primarily associated with the first dose, the company said.
In the study, obese or overweight patients with Type 2 diabetes, who typically lose less weight on GLP-1 therapies, achieved up to about 17% weight loss on average, Amgen said.
In patients with and without diabetes - a "plateau" was not observed, indicating potential for further weight loss beyond 52 weeks, Amgen said.
The mid-stage study showed no association between the drug and bone mineral density changes, after such concerns following early-stage data wiped off more than $12 billion from its market value.
