Maridebart Cafraglutide (MariTide)

Mechanism

Maridebart cafraglutide has a novel dual mechanism: it is a GLP-1 receptor agonist combined with a GIP receptor antagonist. The GLP-1 agonism component enhances glucose-dependent insulin secretion, slows gastric emptying, and reduces appetite — consistent with the GLP-1 agonist class. The GIP receptor antagonism component is based on the hypothesis that chronic GIP receptor activation may contribute to obesity-related metabolic dysfunction, and that blocking GIP signalling may enhance weight loss. This is mechanistically distinct from dual GIP/GLP-1 agonists (tirzepatide, VK2735) which activate both receptors. MariTide is a peptide conjugated to an antibody scaffold (peptide-antibody conjugate), which contributes to its long half-life and suitability for monthly dosing.

Evidence base

Published Evidence

**Phase 2 RCT (2025)**¹ — Randomised, double-blind, placebo-controlled trial of monthly subcutaneous maridebart cafraglutide in adults with obesity, with 52-week follow-up. The highest dose produced up to approximately 20% mean weight loss from baseline. A clear dose-response was observed. Gastrointestinal adverse events (nausea, vomiting, diarrhoea) were the most common side effects, predominantly mild to moderate.

Preliminary / Unpublished Data

Amgen has reported additional Phase 2 data in press releases, including longer-duration extension data and dose optimisation results. These have not been fully peer-reviewed as of mid-2025 and should be treated as preliminary.

Evidence Gaps

• No Phase 3 confirmatory trials completed
• No cardiovascular outcomes trial
• No head-to-head comparisons with tirzepatide or other incretin agonists
• Limited long-term safety data beyond the Phase 2 follow-up period
• No data on the bone health effects of chronic GIP receptor antagonism (a theoretical concern given GIP receptor expression in bone tissue)
• No data in special populations (adolescents, elderly, renal/hepatic impairment)

Evidence Grade: Moderate

One well-designed Phase 2 RCT with 52-week follow-up provides solid preliminary evidence. Phase 3 confirmation is required before efficacy and safety can be considered established.

Protocols

MariTide does not have established protocols outside of clinical trials. In the Phase 2 trial, it was administered as a monthly subcutaneous injection with dose escalation. No research-use protocols exist, and the compound is not available from research peptide vendors.

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UK legal status

MariTide is not licensed as a medicine in the UK and has not been assessed by the MHRA. It is an investigational pharmaceutical compound under development by Amgen Inc. It is not a controlled substance, but it is also not legally available for purchase outside of clinical trial frameworks. The MHRA has issued warnings about fake and unlicensed weight-loss injectable pens; any MariTide sold outside clinical trials should be considered suspect.