Amgen Inc. announced on Tuesday that its experimental weight-loss drug, MariTide, demonstrated an average weight reduction of up to 20% over a year in a critical mid-stage clinical trial. Despite the positive results, the company's stock dropped 10%, as analysts expressed skepticism over whether the drug met the high expectations for its potential in the competitive obesity treatment market.
The trial revealed that patients with obesity experienced an average weight loss of 20% after 52 weeks, while those with both obesity and Type 2 diabetes saw a 17% reduction. The drug, which is administered monthly or even less frequently, could offer a convenience advantage over existing weekly injections such as Novo Nordisk's Wegovy and Eli Lilly's Zepbound. Amgen emphasized this unique feature as a key differentiator in the burgeoning market for weight-loss medications.
"Based on these data, we believe MariTide has a unique differentiated and competitive profile, which we will explore in phase three development," Amgen CEO Robert Bradway said during a call with investors.
Amgen tested multiple dosing regimens, including both monthly and bi-monthly injections. Results showed that patients on the highest dose every other month achieved weight loss comparable to those receiving monthly doses. This finding could significantly reduce the frequency of treatment without compromising effectiveness.
"MariTide's synergistic molecular design requires only a fraction of the peptide supply with fewer injections and fewer devices versus weekly injectable alternatives," Bradner said during the Tuesday call.
The study involved 592 participants, including 465 individuals with obesity and 127 with both obesity and Type 2 diabetes. Patients were divided into 11 groups to test various dosing levels and schedules. For example, some groups followed a rapid dose escalation over four weeks, while others used a slower approach over 12 weeks. The drug's innovative peptide-antibody conjugate design, which targets GLP-1 and blocks GIP receptors, represents a new approach to weight-loss treatments.
Despite these encouraging findings, Wall Street was underwhelmed. Analysts had hoped for weight loss results ranging from 20% to 25%, and some saw the data as falling short of the expectations set by competitors. Mizuho healthcare expert Jared Holz noted that Amgen's delayed entry into the market, combined with uncertainties over which dose to advance into phase three trials, could be a disadvantage.
"AMGN did not disclose which dose it plans to move forward, but would guess that the higher doses are driving better weight loss so need to consider how the side effect profile looks in these specific formulations," Holz wrote in a note to clients.
Amgen's stock fell over 10%, closing at $260 on Tuesday. This marked a significant setback for a company that has seen its shares rise in anticipation of the trial results. The drop reflects investor concerns about how MariTide will stack up against established competitors in a market forecasted to reach $150 billion annually by the early 2030s.
Competing drugs have already demonstrated strong results. Novo Nordisk's Wegovy showed 15% weight loss in late-stage studies, while Eli Lilly's Zepbound achieved more than 22%. Both drugs have the advantage of being well-established, giving them a significant head start over MariTide. Analysts also raised questions about side effects related to MariTide, although Amgen has dismissed concerns about the drug's impact on bone density.
The trial's findings also included data on side effects. Around 11% of participants discontinued treatment due to adverse effects, with gastrointestinal symptoms such as nausea and vomiting being the most common. These side effects were described as mild to moderate and were primarily associated with the first dose of the drug. Bradner noted that Type 2 diabetes patients, who are known to respond less favorably to weight-loss medications, were excluded from groups that tested less frequent dosing regimens.
Amgen is using the results of this trial to shape its phase three study, which is already in advanced planning stages. The company plans to investigate MariTide's long-term potential as a maintenance drug and explore quarterly dosing regimens. The second part of the phase two trial will evaluate the durability of the drug's weight-loss effects and examine how quickly patients regain weight when taken off the medication.
"We're eager to see how quickly people who lost weight rebound when they come off the medicine," Bradner said in an interview earlier this month.
