What Is MariTide?

1. What Is MariTide?

MariTide is Amgen’s investigational maridebart cafraglutide, formerly AMG 133. Amgen describes it as a long-acting peptide-antibody conjugate given subcutaneously monthly or less frequently in research. Its April 30, 2026 pipeline chart lists the molecule as being investigated for obesity and several obesity-related conditions.

Naming terminology:

AMG 133, maridebart cafraglutide, and MariTide all refer to the same investigational drug.

2. How Does MariTide Work?

Amgen’s pipeline chart says maridebart cafraglutide activates the glucagon-like peptide-1 (GLP-1) receptor and antagonizes the glucose-dependent insulinotropic polypeptide receptor (GIPR). Nature Metabolism describes the earlier AMG 133 molecule as an anti-GIPR antagonist antibody conjugated to two GLP-1 analogue agonist peptides.

In short, it activates one incretin pathway and blocks another.

That makes MariTide different from tirzepatide at the mechanism level. Tirzepatide labels describe GIP and GLP-1 receptor agonism. MariTide is described as GLP-1 receptor agonism plus GIP receptor antagonism.

Molecule comparison:

3. Is MariTide FDA-Approved?

No. MariTide is not FDA-approved as of May 6, 2026. Amgen’s 2026 pipeline chart lists maridebart cafraglutide as being investigated, and ClinicalTrials.gov records show Phase 3 studies rather than an approved U.S. prescribing label.

While published phase 2 trials support Phase 3 development, they do not create an approved indication, a dosing label, a pharmacy product, or safe-use instructions for the public.

4. What Did the Phase 2 Study Report?

The completed phase 2 study, ClinicalTrials.gov NCT05669599, enrolled 592 adults with overweight or obesity, with or without type 2 diabetes. PubMed lists the New England Journal of Medicine paper as “Once-Monthly Maridebart Cafraglutide for the Treatment of Obesity,” published in 2025.

Amgen’s June 23, 2025 release reported 52-week data from Part 1 of that study. In people living with obesity without type 2 diabetes, Amgen reported up to about 20% average weight loss compared with 2.6% in the placebo arm under the efficacy estimand. In people living with obesity and type 2 diabetes, Amgen reported up to about 17% average weight loss compared with 1.4% in placebo.

Weight-loss responses in trials often differ by diabetes status, and Amgen reported the two groups separately.

Amgen also reported A1C reduction up to 2.2% in people living with obesity and type 2 diabetes.

5. What About Monthly or Less Frequent Dosing?

Amgen describes MariTide as subcutaneously administered monthly or less frequently in clinical trials. Most familiar incretin medicines are once-weekly injections or daily oral tablets.

Currently, this less frequent dosing schedule remains part of the investigational study design and has not been approved by regulators.

6. What Is the MARITIME Program?

MARITIME is Amgen’s Phase 3 clinical trial program for maridebart cafraglutide. Amgen says MARITIME-1 studies adults with overweight or obesity, while MARITIME-2 studies adults with type 2 diabetes and overweight or obesity.

NCT06858839, MARITIME-1, is a Phase 3 randomized, double-blind, placebo-controlled study in adults without type 2 diabetes who have obesity or overweight. The record showed actual enrollment of 3,853 and active-not-recruiting status when checked.

NCT06858878, MARITIME-2, is a Phase 3 randomized, double-blind, placebo-controlled study in adults with type 2 diabetes mellitus who have obesity or overweight. The record showed actual enrollment of 1,105 and active-not-recruiting status when checked.

Amgen also lists broader Phase 3 work. NCT07037433, MARITIME-CV, studies cardiovascular outcomes in participants with atherosclerotic cardiovascular disease and overweight or obesity, with estimated enrollment of 12,800 and recruiting status when checked.

7. How Is MariTide Different From Semaglutide or Tirzepatide?

MariTide is different by molecule, mechanism, and status. Semaglutide is a GLP-1 receptor agonist active ingredient in approved brands such as Ozempic, Wegovy, and Rybelsus. Tirzepatide is a GIP and GLP-1 receptor agonist active ingredient in approved brands such as Mounjaro and Zepbound. MariTide is investigational maridebart cafraglutide.

8. Summary of Key Facts

For related molecule background, see What Is a GLP-1?, What Is Semaglutide?, What Is Tirzepatide?, and What Is Retatrutide?.

9. What Is MariTide FAQ

• What is MariTide in simple terms?

  MariTide is Amgen's investigational name for maridebart cafraglutide, formerly AMG 133. Amgen describes it as a long-acting peptide-antibody conjugate that activates GLP-1 receptors and blocks GIP receptors.

• Is MariTide FDA-approved?

  No. MariTide is currently investigational and in clinical trials. Amgen's April 30, 2026 pipeline chart notes maridebart cafraglutide is being investigated for obesity, type 2 diabetes, cardiovascular disease, heart failure, obstructive sleep apnea, and elevated liver fat.

• Is MariTide the same as maridebart cafraglutide?

  Yes. MariTide is the short name Amgen uses for maridebart cafraglutide. Older sources refer to the molecule as AMG 133.

• How is MariTide different from tirzepatide?

  Tirzepatide labels describe GIP and GLP-1 receptor agonism. MariTide is described as a GLP-1 receptor agonist and a GIP receptor antagonist.

• What did Amgen report in phase 2?

  Amgen reported phase 2 52-week results with up to about 20% average weight loss in people with obesity without type 2 diabetes and up to about 17% average weight loss in people with obesity and type 2 diabetes, using the efficacy estimand.

10. Sources