Amgen reports 52-week Phase 2 data for MariTide and redesigns Phase 3 dosing

Amgen presented 52-week results from its Phase 2 study of MariTide (maridebart cafraglutide) at the American Diabetes Association's 85th Scientific Sessions and published them in the New England Journal of Medicine. Participants with obesity but without type 2 diabetes lost up to about 20% of their body weight, with no sign of a weight-loss plateau by the end of the study, while participants who also had type 2 diabetes lost up to about 17% ^[3].

MariTide is not another weekly peptide injection. It is a peptide-antibody conjugate that blocks the GIP receptor while activating the GLP-1 receptor. Because it stays in the body much longer than existing drugs, it can be given as infrequently as once a month — a possible adherence advantage over weekly shots ^[3]. The Phase 2 study that produced these results was registered as a dose-ranging trial of AMG 133 in adults with overweight or obesity, with or without type 2 diabetes ^[1].

Jay Bradner, Amgen's head of research and development, called the results "a defining advance for the obesity field" ^[3]. The Phase 3 program, called MARITIME, is now running in obesity and type 2 diabetes, with additional studies planned in cardiovascular disease, heart failure and obstructive sleep apnea ^[3].

A few things the available sources do not settle. The exact side-effect rates from the 52-week study, including how often nausea and vomiting occurred and how many people stopped treatment, are not reported in these sources, and neither is the specific dose-escalation schedule Amgen plans to use in Phase 3. The "up to" figures are also top-dose results, so they describe the best-performing group rather than an average across everyone who took the drug.

How it compares

Cross-trial comparisons are rough, because these drugs were not tested head to head and different trials use different analysis methods. With that caveat: Eli Lilly's retatrutide, a weekly triple agonist, reported a 25.0% average weight change at 80 weeks in the Phase 3 TRIUMPH-1 trial under the treatment-regimen analysis, and 28.3% under the efficacy analysis that assumes everyone stayed on treatment ^[4]. Novo Nordisk's CagriSema delivered around 23% in its REDEFINE Phase 3 program and was filed with the FDA on December 18, 2025 ^[3][4]. Among approved pills, the Wegovy tablet (oral semaglutide 25 mg) showed a 13.6% mean change at week 64 in OASIS 4, and Foundayo (orforglipron) showed 11.2% at 72 weeks in ATTAIN-1 under its primary analysis ^[4].

So MariTide's Phase 2 numbers land in the same general range as several competitors — but its distinguishing feature is dosing frequency, not raw efficacy.

Why it matters for patients

MariTide is investigational. It is not approved by the FDA, and as of July 2026 it was still in Phase 3 ^[4]. Nothing about these results changes what is available at a US pharmacy today.

What the data suggest is that the menu of options is widening. If MariTide reaches the market, patients and prescribers would be choosing among monthly injections, weekly injections and daily tablets, with different side-effect and convenience trade-offs ^[3]. A monthly shot means roughly 12 injections a year instead of 52, which matters for people who struggle to keep up with a weekly routine, or who travel, or who have trouble storing medication.

The absence of a plateau at 52 weeks is also notable, because it raises the question of how much more weight people might lose with longer treatment ^[3]. Phase 3 is designed to answer that with larger numbers and longer follow-up.

What happens next

Pivotal MARITIME data are expected to read out through 2027 ^[3]. Amgen's spending reflects the scale of the bet: the company reported that higher research and development expenses in the second quarter of 2026 were driven primarily by later-stage clinical programs related to MariTide ^[2]. No FDA filing date has been announced in these sources.