Amgen says obesity drug MariTide caused up to 20% weight loss after one year
The Amgen logo is displayed in front of the Amgen headquarters in Thousand Oaks, California on May 17, 2023.
Mario Tama | Getty Images
Amgen said Tuesday its experimental weight-loss injection helped patients with obesity lose up to 20% of their weight on average after a year in a critical mid-stage trial, as the company fights to break into the booming obesity drug market to get in.
The drug MariTide also helped patients with obesity and type 2 diabetes lose up to 17% of their weight after one year. The company said it did not observe a plateau in any of the patient groups, indicating the possibility of further weight loss beyond week 52. MariTide was taken monthly or even less frequently in the study – which could offer an advantage over the popular weekly injections on the market.
But Amgen shares fell about 5% on Tuesday as results appeared to be at the low end of Wall Street's lofty expectations for the drug. Ahead of the data release, several analysts said they wanted MariTide to show at least 20% weight loss in the Phase 2 trial, with some hoping for as much as 25%.
Wall Street has been eagerly awaiting the results of the study, which will shed light on how Amgen's drug competes with blockbuster weight-loss injections Novo Nordisk And Eli Lilly and a crowded field of treatments being developed by other drugmakers.
Jared Holz, healthcare equity strategist at Mizuho, ​​said in an email Tuesday: “We feel investors have even more confidence in Eli Lilly and Novo Nordisk as leaders in the weight loss drug market.” He noted that Amgen could potentially be a “distant third/fourth player” in this space, as MariTide likely won't come to market until around 2027.
Amgen only released data on the first of two yearlong parts of the study, which tested different dose sizes, schedules and treatment regimens of MariTide. The main goal of the study was to measure the extent of weight loss, but it also looked at how long participants could go between injections and still lose pounds.
Specifically, Amgen said patients who received the highest dose of MariTide every two months experienced comparable weight loss to those who took it monthly, suggesting the possibility of less frequent dosing of the drug.
Approximately 11% of patients in the study discontinued treatment due to adverse side effects, while less than 8% discontinued treatment specifically due to gastrointestinal side effects. Gastrointestinal side effects were predominantly mild to moderate and were primarily related to the first dose of the drug.
Amgen said dose escalation, in which patients start with a lower dose of MariTide and gradually increase it until they reach a higher target dose, significantly improved the frequency of these side effects in the study.
“Based on this data, we believe MariTide has a unique, differentiated and competitive profile that we will explore in the third phase of development,” Amgen CEO Robert Bradway said on a post-earnings call with investors on Tuesday.
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The company will use the results of the first part to “determine the fine details” of the design of its late-stage trial of the treatment, which is “already deep in planning,” Amgen Chief Scientific Officer Jay Bradner said earlier in a statement Interview this month.
Amgen said MariTide could provide faster weight loss, potentially better weight maintenance and fewer injections than weekly injections such as Novo Nordisk's Wegovy and Eli Lilly's Zepbound. That could boost Amgen's chances of capturing a slice of the weight-loss drug market, which some analysts predict could be worth $150 billion a year by the early 2030s.
Later studies of Wegovy showed that it resulted in 15% weight loss within 68 weeks, while Zepbound helped patients lose more than 22% of their weight within 72 weeks.
MariTide offers a new approach to weight loss compared to drugs already on the market because it is a so-called peptide-antibody conjugate, which is a monoclonal antibody bound to two peptides. The peptides activate receptors of a gut hormone called GLP-1, while the antibody blocks receptors of another hormone called GIP hormone.
This is different than Eli Lilly's obesity drug Zepbound, which activates both GIP and GLP-1. Wegovy activates GLP-1 but does not target GIP, which can also affect how the body breaks down sugar and fat.
“MariTide's synergistic molecular design requires only a fraction of the peptide supply with fewer injections and fewer devices compared to weekly injectable alternatives,” Bradner said on Tuesday's conference call.
Amgen shares have risen this year in anticipation of midterm study data. That rally lost steam in recent weeks when an analyst raised questions about MariTide's possible side effects related to bone density. Amgen has stated that it has no concerns about MariTide's bone density data.
Experimental design
The first part of the phase 2 study examined 592 patients, including 465 patients with obesity and 127 patients with obesity and type 2 diabetes. The study examined MariTide in 11 different patient groups, with researchers testing different treatment regimens and dosage levels – 140, 280 and 420 milligrams.
For example, some groups used rapid dose escalation, in which patients were started on a lower dose of MariTide and gradually increased over four weeks until they reached a higher target dose. Others experienced a slower dose increase over 12 weeks.
Several groups took MariTide once a month, while one group took the highest dose of the drug every two months. In an interview, Bradner pointed out that patients with type 2 diabetes “are known to respond less favorably to weight loss medications,” which is why Amgen did not assign them to a group that used dose escalations or less frequent dosing schedules.
More than 90% of eligible patients agreed to participate in the second part of the study, which will examine how durable MariTide's weight loss is. The company is “interested in seeing how quickly people who have lost weight regain their strength after stopping the medication,” Bradner said in the interview.
The second part of the study will also assess progressive weight loss after the first year of taking MariTide and test even more infrequent dosing of the drug. Amgen has not said when it will release data from the second part of the trial.
Patients who continued the study were randomly divided into several groups.
For example, patients who took 140-milligram doses of MariTide in the first part of the study will either continue taking that dose or switch to a placebo for another year, which will measure how long MariTide weight loss lasts. Some people who took 280-milligram doses in the first part of the study will take lower doses of the drug for a year.
Amgen is also testing a quarterly schedule in some patients who took 420-milligram doses in the first part of the study. This means that patients receive a vaccination every 12 weeks.
