Amgen stock tumbled late Tuesday on a report that its high-profile weight-loss shot, MariTide, could be linked to bone mineral density loss.
Cantor Fitzgerald analyst Olivia Brayer reiterated her overweight rating and 405 price target on Amgen shares. But she noted a supplemental filing shows patients lost about 4% of their bone mineral density after receiving a 420-milligram dose of MariTide for 12 weeks.
"On one hand, patients could naturally lose bone mineral density during weight loss treatment (i.e., if they eat too little and diet is not optimized)," she said in the report. "On the other hand, this could be a nonstarter because there seems to be a dose-dependent increase in BMD loss."
Amgen stock skidded 7.1% to close at 298.84.
A representative of Amgen didn't immediately a return request for comment.
Amgen Stock: 'A Big Unknown Risk'
Amgen is testing MariTide as a once-monthly shot, rivaling the weekly injections from Novo Nordisk and Eli Lilly.
Like Lilly's tirzepatide — also called Mounjaro and Zepbound — MariTide mimics the hormone GLP-1. But, while tirzepatide also mimics another hormone called GIPR, MariTide puts the brakes on GIPR. It's the first company to take this approach.
Brayer called the bone mineral density loss "a big and unknown risk" of the GIPR approach. Notably, Pfizer is also developing a drug that, alone, blocks the action of GIPR. Pfizer's drug could be a daily pill.
The potential for bone mineral density loss could impact commercial dynamics.
Mimicking GIPR — like Lilly's tirzepatide and Viking Therapeutics' VK2735 — is thought to increase bone mineral density by decreasing the process by which bone tissue breaks down. So, the duo could have a leg-up on Amgen's MariTide.
Amgen stock has been on a run this year amid its efforts in weight loss. But shares dropped below the lower boundary of a flat base with a buy point at 346.85 on Tuesday, according to MarketSurge.
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