Watch Out, Eli Lilly and Novo Nordisk: Amgen’s Monthly Weight Loss Drug Has 6 Phase 3 Trials Running — and It’s Coming for Your Patients
Alex Carchidi, The Motley Fool
Wed, July 29, 2026 at 5:20 PM GMT+5:30
4 min read
Amgen (NASDAQ: AMGN) is betting that the convenience of its weight loss treatment will make it a winner, and it might be right. Its candidate MariTide is a monthly injection that aims to directly challenge the anti-obesity drugs made by Eli Lilly (NYSE: LLY) and Novo Nordisk (NYSE: NVO), which in their original formulations are administered by a weekly injection
If the program’s phase 3 clinical trial data look good, Amgen could enter the market and become a major player despite having no real presence now. So should Eli Lilly and Novo Nordisk actually start to sweat?
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There may not be a real threat to the incumbents here
MariTide is an antibody-peptide conjugate, which in this case means that it’s an antibody that blocks the receptor for glucose-dependent insulinotropic polypeptide (GIP), and also carries two peptides that activate the receptor for glucagon-like peptide-1 (GLP-1)
The conjugate’s long half-life is what enables dosing only once a month, which could be a major convenience factor for patients, leading to higher market share than competing drugs. In the 592-participant phase 2 trial, adults with obesity and no type 2 diabetes lost 12.3% to 16.2% of their body weight at 52 weeks, against 2.5% on placebo
The trouble is that those results don’t exactly stack up against the competition
Per one head-to-head trial comparing different molecules for weight loss, tirzepatide, which is the molecule in Eli Lilly’s Zepbound, led to 20.2% weight loss, and semaglutide, which is Novo Nordisk’s Wegovy, led to 13.7% weight loss after 72 weeks. MariTide has never been tested against either in a structured trial, but its phase 2 data do not suggest that it would dramatically outperform the leading medicines on the market right now
Amgen’s own language on this topic is instructive. The company’s commercial chief, Murdo Gordon, told investors in April that it expects to be the best “monthly or less frequently dosed” agent in obesity
Getting people to switch will be hard
Amgen will struggle to get patients to shift from their other weight loss therapies if it eventually succeeds in commercializing its candidate
Amgen appears to share that doubt. In May it began an open-label phase 3 study of about 300 adults, moving off GLP-1 drugs and onto MariTide, with results due in 2028. Even if that trial produces some favorable data, it will probably be far too late to matter because by then both Eli Lilly and Novo Nordisk will likely have even newer and better therapies on the market or approaching commercialization
