GIPR:GCGR co-agonism restores normal weight in obese rodents
Perez-Tilve D, Zhang F, Zhang Y, Lohman K, Sorrell J, Vick A, Müller TD, Tschöp MH, +1 more
Molecular Metabolism (2026)
BWB3054, a dual GIPR:GCGR co-agonist designed to attenuate GLP-1R signalling >100-fold, normalised body weight in diet-induced obese mice and rats and matched [retatrutide's](/peptides/retatrutide) weight effect — including in GLP-1R-knockout mice — suggesting the GIP and glucagon arms of the triple-agonist can deliver the bulk of the obesity effect without GLP-1R-driven gastrointestinal liability.
Perez-Tilve and colleagues at the University of Cincinnati Metabolic Diseases Institute, Helmholtz Munich (Müller, Tschöp), and Indiana University (DiMarchi) report a preclinical pharmacology study in Molecular Metabolism dissecting the relative contribution of the three receptor arms — GLP-1R, GIPR, GCGR — that combine in the retatrutide triple agonist. The DiMarchi-Tschöp axis is the same medicinal-chemistry program that originated the unimolecular dual and triple-agonist design strategy now embodied in tirzepatide and retatrutide; this paper extends that program by asking whether the GLP-1R arm can be substantially attenuated without losing the obesity efficacy that retatrutide delivers.
The investigators designed BWB3054, a peptide co-agonist with potent GIPR and GCGR activity and with GLP-1R potency reduced by more than 100-fold relative to retatrutide. In diet-induced obese (DIO) wild-type mice, BWB3054 produced weight loss comparable to retatrutide and restored body weight toward lean controls. In GLP-1R-knockout mice — where any residual GLP-1R activity is functionally irrelevant — BWB3054 also produced weight loss, demonstrating that the obesity phenotype can be reversed in the absence of functional GLP-1R signalling. The investigators extended the work into DIO rats, where the weight loss observation replicated.
The interpretive frame is twofold. First, the GLP-1R arm is not strictly required for the obesity efficacy of retatrutide-class compounds; the GIP and glucagon arms together can carry that load. Second, attenuating GLP-1R activity preserves much of the weight effect while potentially avoiding the GLP-1R-driven gastrointestinal adverse-event profile (nausea, vomiting, slowed gastric emptying) that dominates current GLP-1RA tolerability discussions. This positions GIPR:GCGR co-agonism as a candidate next-generation obesity pharmacology, and re-frames the retatrutide phase-2 obesity, retatrutide T2D phase-2, and retatrutide MASLD phase-2a trial signals as partly driven by non-GLP-1R receptor arms.
This is preclinical rodent pharmacology, not a clinical trial. BWB3054 is a research compound, not a drug candidate in humans as of the publication date, and the inferential chain from DIO-mouse body weight to human chronic obesity therapy is the same long chain that applies to every preclinical co-agonist paper. The work was supported by infrastructure at academic institutions that have historical research and consulting relationships with Eli Lilly (DiMarchi, Tschöp, Müller) — the originating laboratory for tirzepatide and retatrutide — and the Molecular Metabolism paper should be read in that context. The disclosed conflict-of-interest landscape for this team is non-trivial; readers should treat the result as biologically informative but not provenance-blind.
The GLP-1R attenuation strategy assumes that the >100-fold reduction in GLP-1R potency translates to clinically meaningful avoidance of GI side effects in humans. That is plausible but not yet demonstrated; human pharmacology of BWB3054 or analogous compounds has not been reported. The headline finding that obesity can be reversed in GLP-1R-knockout mice is a clean mechanistic dissection of the triple-agonist signal, but it does not predict that human responders to retatrutide derive most of their weight loss from the GIP and glucagon arms — single-agonist GLP-1RAs (semaglutide, liraglutide) clearly produce substantial weight loss in humans, so the relative arm contributions in vivo in humans remain an open question.
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