Mechanism of action
Retatrutide (LY3437943) is a single-molecule agonist of three G-protein-coupled receptors: the glucose-dependent insulinotropic polypeptide receptor (GIPR), the glucagon-like peptide-1 receptor (GLP-1R) and the glucagon receptor (GCGR). In the published pharmacology, GLP-1R activation is associated with glucose-dependent insulin secretion and reduced appetite signalling via hypothalamic satiety circuits; GIPR activation potentiates insulin secretion and is discussed as a possible attenuating factor for nausea; GCGR activation stimulates hepatic lipid oxidation and increases energy expenditure and thermogenesis in preclinical models. The peptide carries a fatty-acid modification that slows elimination; a half-life of roughly six days (about 144 hours), supporting once-weekly administration in the trials, was reported in the phase 2 program (Jastreboff et al., NEJM 2023). The receptor pharmacology of the discovery compound is described in vitro and in animal models by Coskun et al. (Cell Metabolism 2022).
State of evidence
The published evidence covers preclinical characterization and early to mid-stage clinical trial phases. Coskun et al. (Cell Metabolism 2022) describe the discovery of LY3437943, including in vitro receptor pharmacology, animal models and first clinical proof-of-concept data. Two randomized phase 2 trials have been published: in adults with obesity, Jastreboff et al. (NEJM 2023) reported dose-dependent changes in body weight over 48 weeks; in type 2 diabetes, Rosenstock et al. (Lancet 2023) reported changes in HbA1c and body weight versus placebo and dulaglutide. A phase 3 program (TRIUMPH), including a cardiovascular and kidney outcomes trial (NCT06383390), is ongoing; results have not been published. Retatrutide is not approved by any regulatory authority. Long-term efficacy, safety and tolerability have not been established; the phase 2 findings are based on limited populations and study durations and require confirmation in phase 3. Conclusions about therapeutic benefit or risk cannot be drawn at this stage.
Storage and handling
Generic, well-documented handling principles for lyophilized peptides apply: store cool, dry and protected from light. After reconstitution, peptide solutions are typically kept refrigerated (2–8 °C) and used within a limited period of a few days. Product-specific stability data for retatrutide research material are not documented here.
Questions about the research
- What is retatrutide being investigated for in research?
- Retatrutide is studied in metabolic research, primarily in clinical trials on obesity and type 2 diabetes. Published phase 2 trials examined body weight and glycemic parameters; the ongoing phase 3 program (TRIUMPH) also includes cardiovascular and kidney outcomes. Mechanistically, the simultaneous activation of the GIP, GLP-1 and glucagon receptors is the focus of research interest.
- What is the current state of evidence on retatrutide?
- A published preclinical and phase 1 characterization exists (Coskun et al., 2022), along with two randomized phase 2 trials (Jastreboff et al., NEJM 2023; Rosenstock et al., Lancet 2023). Phase 3 trials are ongoing and their results have not yet been published. Retatrutide is not an approved medicine; long-term efficacy and safety have not been established.
Sources
- Jastreboff et al., NEJM 2023DOI: 10.1056/NEJMoa2301972PMID: 37366315
- Coskun et al., Cell Metab 2022DOI: 10.1016/j.cmet.2022.07.013PMID: 35985340
- Rosenstock et al., Lancet 2023DOI: 10.1016/S0140-6736(23)01053-XPMID: 37385280
- ClinicalTrials.gov NCT06383390 (TRIUMPH-Outcomes, Phase 3)