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Preliminary / Unpublished Data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.

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.

Vendor notes

MariTide is not available from any vetted UK vendor. It is an investigational compound under pharmaceutical development and is not sold as a research peptide. Any vendor claiming to sell MariTide should be treated with extreme caution.