# Retatrutide research references — primary citations and DOIs

> Full citation list for the retatrutide research brief, with DOIs and links to PubMed, NEJM, Lancet, Nature Medicine, Cell Metabolism, Cell Discovery, ClinicalTrials.gov, and FDA Warning Letters.

Seventeen primary references — peer-reviewed publications, ClinicalTrials.gov registrations, and FDA enforcement letters — covering the retatrutide literature through 2025.

## About this reference list

The seventeen references below cover the published clinical trials, structural-biology, preclinical, regulatory, and synthesis-review literature on retatrutide (LY3437943) through 2025. They are the citations underlying every quantitative claim made on this site.

Where a DOI is available, it is included. PubMed, PMC, and journal URLs are provided where applicable. Two of the references — TRIUMPH-1 and TRIUMPH-3 — are ClinicalTrials.gov trial registrations rather than published readouts, because both trials are ongoing as of 2026. Two are FDA Warning Letters, included because they are the primary source for the U.S. compounding-eligibility determination.

## How to read the literature

A few orientation notes for readers who want to read the primary sources rather than rely on summaries.

The two foundational reports to read first are the 2022 *Cell Metabolism* discovery paper from Coskun and colleagues, which establishes what the molecule is and how the receptor-activity profile was tuned, and the 2022 Phase 1b *Lancet* paper from Urva and colleagues, which establishes the pharmacokinetic basis for once-weekly dosing. Together they explain the design and dosing rationale that the Phase 2 and Phase 3 programs run on.

The Phase 2 obesity trial (Jastreboff, *NEJM* 2023) is the single most-cited paper in the public discussion of retatrutide. Read the full text and the supplementary appendix — the supplementary appendix carries the dose-escalation schedule, the adverse-event breakdown by cohort and time window, and the 24-week interim efficacy data.

The MASLD substudy (Sanyal, *Nature Medicine* 2024) is the standout among the secondary readouts. The 2024 Cell Discovery cryo-EM paper (Li, Zhou et al.) is the structural-biology companion that explains how a single peptide satisfies three different receptor pockets.

For the regulatory framing, the September 2025 FDA Warning Letters are the primary source. Anyone considering the compounding question should read at least one of them in full — they walk through the statutory tests under FDCA 503A and 503B and explain why retatrutide fails each of them.

## Citation list

See the references index below. Each entry lists authors, journal, year, DOI, and URL.

## References

[1] Jastreboff AM, Kaplan LM, Frias JP, et al. Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. New England Journal of Medicine. 2023. https://www.nejm.org/doi/full/10.1056/NEJMoa2301972
[2] Jastreboff AM, Kaplan LM, Frias JP, et al. Phase 2 obesity trial — 24-week dose-response interim data. New England Journal of Medicine. 2023. https://www.nejm.org/doi/full/10.1056/NEJMoa2301972
[3] Rosenstock J, Frias JP, Jastreboff AM, et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial conducted in the USA. The Lancet. 2023. https://pubmed.ncbi.nlm.nih.gov/37385280/
[4] Sanyal AJ, Kaplan LM, Frias JP, et al. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. Nature Medicine. 2024. https://www.nature.com/articles/s41591-024-03018-2
[5] Urva S, Coskun T, Loh MT, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial. The Lancet. 2022. https://pubmed.ncbi.nlm.nih.gov/36354040/
[6] Coskun T, Urva S, Roell WC, et al. LY3437943, a novel triple GIP, GLP-1 and glucagon receptor agonist for glycemic control and weight loss: from discovery to clinical proof of concept. Cell Metabolism. 2022. https://pubmed.ncbi.nlm.nih.gov/35987202/
[7] Li W, Zhou Q, et al. Structural insights into the triple agonism at GLP-1R, GIPR and GCGR manifested by retatrutide. Cell Discovery. 2024. https://www.nature.com/articles/s41421-024-00700-0
[8] TRIUMPH-4 topline (NCT05931367): retatrutide in adults with obesity and knee osteoarthritis — first successful Phase 3 readout. ClinicalTrials.gov / sponsor press release. 2025. https://clinicaltrials.gov/study/NCT05931367
[9] Jastreboff AM, Kaplan LM, Frias JP, et al. Phase 2 obesity trial — gastrointestinal adverse-event profile and discontinuation rates. New England Journal of Medicine. 2023. https://www.nejm.org/doi/full/10.1056/NEJMoa2301972
[10] Jastreboff AM, Kaplan LM, Frias JP, et al. Phase 2 obesity trial — resting heart-rate trajectory. New England Journal of Medicine. 2023. https://www.nejm.org/doi/full/10.1056/NEJMoa2301972
[11] A Study of Retatrutide (LY3437943) in Participants Who Have Obesity or Overweight (TRIUMPH-1). ClinicalTrials.gov NCT05929066. 2023. https://clinicaltrials.gov/study/NCT05929066
[12] A Study of Retatrutide (LY3437943) in Participants With Obesity and Cardiovascular Disease (TRIUMPH-3). ClinicalTrials.gov NCT05882045. 2023. https://clinicaltrials.gov/study/NCT05882045
[13] Incretin triple agonist retatrutide (LY3437943) alleviates obesity-associated cancer progression. NPJ Metabolic Health and Disease / PMC. 2025. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11908972/
[14] Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial. The Lancet Diabetes & Endocrinology. 2025. https://www.thelancet.com/journals/landia/article/PIIS2213-8587(25)00092-0/abstract
[15] Retatrutide — A Game Changer in Obesity Pharmacotherapy (review). Biomolecules (MDPI) / PMC. 2025. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12190491/
[16] FDA Warning Letter MARCS-CMS 715506 — Amazing Meds. U.S. Food and Drug Administration. 9 September 2025. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/amazing-meds-715506-09092025
[17] FDA Warning Letter MARCS-CMS 716459 — ASN-LABS. U.S. Food and Drug Administration. 9 September 2025. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/asn-labs-716459-09092025
[18] The Effect of Retatrutide Once Weekly on Cardiovascular Outcomes and Kidney Function. Eli Lilly and Company. ClinicalTrials.gov NCT06383390. 2024. https://clinicaltrials.gov/study/NCT06383390
[19] Dietary protein defends lean mass and maintains the metabolic benefits of weight loss. Mol Metab. 2024. https://pmc.ncbi.nlm.nih.gov/articles/PMC11424806/
[20] Weight Regain After GLP-1-Based Therapy Discontinuation: Failure, Physiology, and the Path Forward. Cureus. 2026. https://pubmed.ncbi.nlm.nih.gov/41909366/
[21] Rationale, design and baseline characteristics of the TRANSCEND-CKD trial of retatrutide. Nephrol Dial Transplant. 2025. https://pubmed.ncbi.nlm.nih.gov/41160422/

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