Maridebart Cafraglutide (MariTide): Amgen Obesity Landscape

Maridebart cafraglutide, known as MariTide (AMG 133), is Amgen’s experimental obesity drug, and its main selling point is dosing frequency: Amgen is developing it to be given monthly, or less often. As of November 4, 2026, it is in Phase 3 and no Phase 3 results have been reported.

Mechanism at a glance

Amgen describes MariTide as an antibody-peptide conjugate that activates the GLP-1 receptor and blocks the GIP receptor (GIPR). Amgen says the long-acting design supports starting with monthly dosing, with maintenance possible at as few as four or six doses a year. In the Phase 2 trial, gastrointestinal side effects were common but less frequent with a lower starting dose and dose escalation.

Why it matters

The Phase 2 trial was published in the New England Journal of Medicine (Jastreboff et al., online June 23, 2025). It enrolled 592 adults: 465 with obesity and 127 with obesity and type 2 diabetes. At week 52 (treatment-policy estimand), weight change in the obesity cohort ranged from -12.3% to -16.2% across MariTide arms vs -2.5% on placebo. In the diabetes cohort it ranged from -8.4% to -12.3% vs -1.7%, and HbA1c fell by 1.2 to 1.6 percentage points vs a 0.1 rise. The authors reported no unexpected safety signals. BioSpace reported the November 2024 Phase 2 results as up to 20% weight loss at 52 weeks, at the lower end of investor expectations.

Competitive pressure points

• Frequency vs magnitude: Amgen’s pitch is convenience. On its Q1 2026 call, Amgen’s head of commercial operations, Murdo Gordon, said “I think we are going to be the best monthly or less frequently dosed agent in obesity.” That is a company aspiration, not a trial result.
• Weekly incumbents: Novo’s semaglutide (landscape) and Lilly’s tirzepatide are the established weekly injections, and Novo’s CagriSema is under FDA review (pipeline).
• Next wave from Lilly: oral orforglipron (Foundayo) was approved in the US on April 1, 2026, and Lilly plans a retatrutide FDA submission in Q1 2027 (orforglipron, retatrutide).
• Other mechanisms: Boehringer’s survodutide is a GLP-1/glucagon agonist (landscape).

What to watch

1. First Phase 3 weight-loss data. ClinicalTrials.gov lists MARITIME-1 (3,853 adults without diabetes) and MARITIME-2 (1,105 with type 2 diabetes) with estimated primary completion on January 21, 2027. Amgen’s Q3 release gave no data timing.
2. Tolerability at the Phase 3 dosing scheme. Amgen’s R&D chief said on the Q3 call that “we will have more to share around the efficacy and tolerability of MariTide at the time that these studies read out.”
3. Whether the switch and extension studies show that monthly or less frequent dosing holds weight off.
4. Outcomes trials in cardiovascular disease and heart failure, which are larger and later.

Recent developments

Updated November 4, 2026. Items are drawn from company announcements, regulators and trade press; links go to the sources.

• Nov 3, 2026: Amgen’s Q3 release listed MARITIME-1 and -2 as ongoing; MARITIME-CV (cardiovascular outcomes) and both sleep apnea studies (OSA-1 and OSA-2) as fully enrolled; MARITIME-HF, MARITIME-SWITCH and the two extension studies as enrolling; MARITIME-T2D-3 (versus semaglutide) as initiated; and two more type 2 diabetes Phase 3 studies as due to start in Q4 2026. (Amgen)
• Nov 3, 2026: On the Q3 call, Amgen executives said MariTide “is emerging as the first monthly therapy for obesity” and described “a simple three-step dose escalation.” The CFO said 2026 capital spending of about $2.6 billion aims to “prepare for potential MariTide launch.” No filing timeline was discussed. (Investing.com transcript)
• May 1, 2026: BioSpace reported that Amgen had launched MARITIME-SWITCH, which tests moving patients from weekly GLP-1 drugs to MariTide. (BioSpace)
• Jun 23, 2025: Phase 2 results published in NEJM. (Europe PMC record)

Upcoming catalysts

• Q4 2026: start of two further Phase 3 type 2 diabetes studies (Amgen).
• January 2027 (registry estimate): primary completion of MARITIME-1 and MARITIME-2.
• June 2028 (registry estimate): primary completion of the cardiovascular outcomes (MARITIME-CV, about 12,800) and heart failure (about 5,056) trials.

Bottom line

MariTide’s case rests on monthly or less frequent dosing and tolerability under a stepped dose, and both will be tested in Phase 3 data that has yet to appear. Until then its weight-loss numbers come only from Phase 2.

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This article is for informational and competitive-intelligence purposes only and is not medical advice. Approvals, labels and trial results change; verify details against current prescribing information and primary sources.