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Actions of amgen fell more than 7% on Tuesday as analysts analyzed bone density loss data from an early-stage trial of its experimental weight-loss injection, MariTide.
An analyst said the additional data suggests a new potential safety risk related to the drug. But others said the stock move was an overreaction and that more data is needed on a larger group of patients.
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 administered monthly, rather than once a week like existing injections of Nordisk and Eli Lillyand promotes weight loss differently.
Wall Street is awaiting crucial results from the MariTide phase two trial, which will be released before the end of the year.
On Tuesday, analysts cited additional publicly available data from a phase one study showing that the highest dose of MariTide (420 milligrams) was linked to about 4% loss of bone mineral density over 12 weeks. A decrease in bone mineral density refers to when bones lose calcium and other minerals, which weakens them and makes them more likely to break.
In a research note, Cantor Fitzgerald analyst Olivia Brayer called the data a “big unknown” and suggested it could be a potential risk associated with drugs like MariTide, which work through so-called GIPR antagonism. The Amgen 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 anti-obesity drug, Zepbound, which activates 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.
“On the one hand, patients could naturally lose bone mineral density during weight loss treatment,” Brayer wrote.
But Brayer said that “on the other hand, this could be a failure because there appears to be a dose-dependent increase” in bone mineral density loss. That means patients appear to lose more bone mineral density the higher the dose they take.
Meanwhile, Jefferies analyst Michael Yee wrote in a note that the additional data from MariTide appears to be “not an issue.” Yee acknowledged that people taking the highest dose of the drug had decreases in bone density, but said “the data is all over the place.”
For example, he pointed to data on a lower dose 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 medications in the first one to three months of use because people lose significant weight quickly.
Amgen is also aware of “hypothetical concern” about loss of bone mineral density, Yee said, citing the company's conversations with management.
“While we're obviously not saying the effect is zero, we do say we don't think there's any concern, [bone mineral density] sustained decline over time, or clinical risk or concern,” Jefferies said. “Overall, we don't think there is a problem and the effect normalizes over time.”
BMO analyst Evan Seigerman wrote in a note Tuesday that “we would be cautious about making a global judgment on MariTide's safety profile with this data.”
He added that “we would feel more comfortable judging the safety profile of a larger cohort of patients.” There may not be a clear answer until Amgen releases full data from the phase two trial on the drug.
“Our opinion of MariTide has not changed with this and, if anything, we consider the sale to be overstated,” Seigerman wrote.
