MariTide (Maridebart Cafraglutide, Investigational)

MariTide (maridebart cafraglutide) is Amgen's investigational antibody-peptide conjugate for obesity that targets the GLP-1 receptor as an agonist while simultaneously antagonizing the GIP receptor — a mechanistic approach that is the inverse of tirzepatide, which agonizes both GIP and GLP-1. The rationale is that blocking GIP signaling, rather than activating it, may reduce the energy-storing properties of GIP in adipose tissue while still benefiting from GLP-1-mediated appetite suppression. This hypothesis is pharmacologically contested — tirzepatide's GIP agonism clearly works — but MariTide's Phase 2 data demonstrate that GIP antagonism combined with GLP-1 agonism also produces meaningful weight loss. The Phase 2 trial results, published in the New England Journal of Medicine and presented at the American Diabetes Association's 85th Scientific Sessions, showed up to approximately 20% weight loss in non-diabetic adults with obesity after 52 weeks. Among participants with type 2 diabetes, weight loss reached approximately 17%, with HbA1c reductions of up to 1.6 percentage points and a high percentage achieving normoglycemia. Crucially, MariTide also demonstrated sustained weight loss for up to 52 weeks after the treatment period ended in some dose groups — a potential durability advantage over peptide-based GLP-1s, whose effects wane quickly after discontinuation. MariTide's most structurally distinctive feature is its dosing frequency: it is being developed as a once-monthly injection, and potentially even a once-quarterly formulation in the longer term, versus weekly injections for all current GLP-1s. This represents a paradigm-shifting convenience advantage if confirmed in Phase 3. However, Phase 2 results disappointed Wall Street relative to pre-release expectations (as reported by BioPharma Dive), and Phase 3 data will be decisive. Phase 3 studies are underway and will read out over 2026-2027.