AT7687vsMariTide

AT7687 is a long-acting GIP receptor antagonist designed to reduce fat storage rather than suppress appetite — a fundamentally different mechanism from every other obesity drug currently on the market or in late-stage development. The rationale is grounded in human genetics: loss-of-function variants in the GIP receptor are associated with lower body mass index and reduced cardiometabolic risk, suggesting that pharmacologically blocking GIP signalling should reproduce these protective effects.

GIP (glucose-dependent insulinotropic polypeptide) normally functions as a fat-storage signal — released from intestinal K-cells in response to food intake, it instructs adipose tissue to take up and store circulating fatty acids. By blocking the GIP receptor specifically on adipocytes, AT7687 prevents this fat-storage signal from being transmitted, leading to reduced lipid uptake into fat cells and a metabolic shift favouring fat oxidation in muscle and liver. Because the mechanism does not depend on suppressing hunger or slowing gastric emptying, the gastrointestinal side effects that limit GLP-1 drug tolerability are largely absent.

This mechanism is the conceptual mirror of MariTide (which combines GLP-1 agonism with GIP antagonism in a single molecule) — AT7687 isolates the GIP-antagonist component to test whether it can produce meaningful weight loss alone or in future combination with GLP-1 agonists. Antag Therapeutics' first-in-human Phase 1 results in 2026 showed acceptable tolerability with mild GI symptoms, plus reductions in LDL cholesterol and resting heart rate — early signals consistent with the predicted cardiometabolic benefit profile. Phase 2 trials are expected to define the magnitude of weight loss achievable in obese patients.

MariTide (maridebart cafraglutide) is a peptide-antibody conjugate combining a GLP-1 receptor agonist peptide with a GIP receptor antagonist antibody. This dual GLP-1 agonist + GIP antagonist mechanism is distinctive — most competing dual incretin drugs (tirzepatide, CT-388, VK2735) activate both receptors. The rationale for GIP antagonism is based on genetic and pharmacological evidence that loss-of-function in GIP signalling is associated with reduced obesity, suggesting that blocking rather than activating GIP may produce superior weight-loss outcomes.

The GLP-1 agonist component drives the established appetite-suppression and glycemic-control effects of the incretin pathway. The GIP receptor antagonist antibody simultaneously blocks GIP signalling at adipocytes and centrally, which preclinical data suggest enhances energy expenditure, reduces lipid storage, and amplifies the weight-loss effect of GLP-1 receptor activation. Whether GIP agonism (as in tirzepatide) or GIP antagonism (as in MariTide) is superior remains an open question that Phase 3 head-to-head data may eventually resolve.

The antibody-conjugated structure produces an exceptional pharmacokinetic profile, with a half-life of approximately three weeks. This supports once-monthly subcutaneous dosing — a unique practical advantage over the once-weekly schedules of all other late-stage obesity drugs. Phase 2 results showed roughly 20% body weight loss at 52 weeks. Animal studies have also suggested slower weight regain after discontinuation than seen with shorter-acting GLP-1 agonists, possibly due to the prolonged drug exposure during the washout period. Phase 3 MARITIME trials launched in 2026 will define the molecule's clinical positioning.