Amgen announces first MariTide Phase 3 results
On 4 November 2025, Amgen announced positive topline results from its first Phase 3 clinical trial of maridebart cafraglutide (MariTide) in obesity. The investigational peptide is a dual-action molecule that acts as a GIP receptor antagonist and GLP-1 receptor agonist, administered as a monthly subcutaneous injection.
The Phase 3 programme follows promising Phase 2 data presented at the American Diabetes Association (ADA) Scientific Sessions in June 2025, which showed sustained weight loss over 52 weeks of treatment.
Mechanism: a differentiated approach
MariTide's mechanism distinguishes it from other incretin-based therapies. Rather than agonising both the GIP and GLP-1 receptors (as tirzepatide does), MariTide antagonises the GIP receptor while agonising the GLP-1 receptor. This approach is hypothesised to provide weight loss through both central appetite suppression and peripheral metabolic effects, including potential benefits on fat oxidation and insulin sensitivity.
The molecule is also designed for extended duration of action, enabling once-monthly dosing — a significant potential advantage over the weekly dosing schedules of currently approved GLP-1 agonists such as semaglutide (Wegovy) and tirzepatide (Mounjaro).
What the Phase 2 data showed
In the Phase 2 trial, MariTide demonstrated dose-dependent weight loss of up to approximately 20% at 52 weeks in participants with obesity. The drug was generally well tolerated, with gastrointestinal adverse events (nausea, vomiting) being the most commonly reported side effects — consistent with the GLP-1 agonist class.
Phase 3 context
The MariTide Phase 3 programme includes multiple trials evaluating the drug in obesity and related conditions. Amgen has indicated that the first Phase 3 study focused on weight loss in adults with obesity or overweight with weight-related comorbidities.
Detailed efficacy and safety data — including the magnitude of weight loss achieved, safety profile, and discontinuation rates — are expected to be presented at an upcoming medical conference and published in a peer-reviewed journal.
Competitive landscape
MariTide enters an increasingly competitive GLP-1/incretin landscape. Eli Lilly's tirzepatide and Novo Nordisk's semaglutide dominate the current market, while retatrutide (triple agonist), orforglipron (oral GLP-1), and CagriSema (amylin/GLP-1 combination) represent other advanced candidates. MariTide's monthly dosing and differentiated GIP-antagonist mechanism could position it as a distinct option if Phase 3 results continue to be positive.
UK relevance
As of November 2025, MariTide is not licensed by the MHRA or EMA. It remains an investigational compound in clinical development. UK researchers should note that any MariTide peptide encountered outside of clinical trials is unlicensed and not approved for human use. The compound is classified as a research chemical for in vitro and laboratory research purposes only.
This article is for research and educational purposes only. It does not constitute medical advice. MariTide (maridebart cafraglutide) is an investigational compound not approved for human use outside of clinical trials.
This article is AI-researched and editorially reviewed. It is provided for research and educational purposes only and is not medical advice. Research peptides are not licensed for human consumption in the UK.