shares Amgen Shares fell more than 7% on Tuesday as analysts scrutinized data on bone density loss in an early trial of its experimental weight-loss injection MariTide.
One analyst said the additional data showed new potential safety risks with the drug. But others said the move was an overreaction and that more data on more patients was needed.
Amgen did not immediately respond to a request for comment on the data.
The drug is a promising potential competitor in the weight-loss drug market. It is designed to be injected once a month, rather than once a week like existing injectables Novo Nordisk and Eli Lilly and Companyand promote weight loss in different ways.
Wall Street is awaiting results from MariTide’s pivotal Phase 2 trial, which should be released before the end of the year.
Analysts on Tuesday cited additional public data from a Phase 1 study showing that the highest dose of MariTide (420 mg) was associated with an approximately 4% decrease in bone mineral density over 12 weeks. Decreased bone mineral density is when bones lose calcium and other minerals, making them more fragile and more susceptible to fractures.
Cantor Fitzgerald analyst Olivia Brayer called the data a “huge unknown” in a research note and suggested it could be a potential risk associated with drugs like MariTide, which work through so-called GIPR antagonism. Amgen’s injection works by blocking a gut hormone receptor called GIP, but also activates another appetite-suppressing hormone called GLP-1.
This is different from Eli Lilly’s obesity drug Zepbound, which activates GIP and GLP-1. Wegovy activates GLP-1, but not GIP, which may also affect how the body breaks down sugar and fat.
“On the one hand, patients may naturally lose bone mineral density during weight loss treatment,” Breyer wrote.
But “on the other hand, that may not be feasible because there appears to be a dose-dependent increase in bone mineral density loss,” Breyer said. This means that the higher the dose a patient takes, the greater the loss of bone mineral density.
Meanwhile, Jefferies analyst Michael Yee wrote in a note that additional MariTide data does not appear to be an issue. Yee acknowledged that people taking the highest doses of the drug experienced a decrease in bone density, but said “the data is all over the place.”
For example, he pointed to data from lower doses of the drug showing that bone density actually increased by 1% before normalizing. Yee added that “changes” in bone mineral density are a known side effect of weight-loss drugs within the first one to three months of use, as people lose weight quickly.
Amgen is also aware of “hypothetical concerns” about reduced bone mineral density, Yee said, citing the company’s discussions with management.
“While obviously not saying the impact is zero, we do not believe there is any concern that there will be a sustained significant decline in (bone mineral density) over time, nor is there any clinical risk or concern,” Jeffries said. “Overall “We do not believe there is a problem and the impact will normalize over time.”
“We are cautious about using this data to make an overall judgment on MariTide’s safety profile,” BMO analyst Evan Seigerman wrote in a note on Tuesday.
He added, “We will feel more comfortable judging safety from a larger patient population.” There may not be a clear answer until Amgen releases complete Phase 2 trial data for the drug.
“Our view on MariTide has not changed, and if anything, we believe the sell-off was overdone,” Segelman wrote.
