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Retatrutide Phase 3 Results: What TRIUMPH-1, TRIUMPH-2, and TRIUMPH-3 Report

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PBIPeptide Bio Index Editorial DeskSource-labeled research summary
Source-limited9 min readUpdated Aug 28, 2026
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  1. What the TRIUMPH program is (design features reported)
  2. Which TRIUMPH endpoints and populations were specified in the reviewed design paper
  3. Phase 2 evidence that informed TRIUMPH dose selection and expectations
  4. Phase 3 evidence present in the reviewed sources (non‑TRIUMPH) and status of TRIUMPH results
  5. Implications for interpreting the current evidence base
  6. Reported study-design details from cited sources
  7. Limitations and research gaps
  8. Documentation checklist
  9. Related research supplies
  10. More Retatrutide research
  11. Sources and references

Disclosure: Peptide Bio Index is affiliated with SourcePoint Research and may earn from qualifying purchases or affiliate links.

This article summarizes published research and reported study designs. It is not medical advice, dosing guidance, or a personal-use recommendation.

Source-limited research note: The reviewed sources were incomplete, ambiguous, or insufficient for a normal article. This page labels missing details rather than guessing.

This evidence deep dive summarizes what the reviewed sources report about the TRIUMPH Phase 3 program for retatrutide (a GIP/GLP‑1/glucagon triple receptor agonist) and what the reviewed literature actually contains about Phase 3 results relevant to TRIUMPH-1, TRIUMPH-2, and TRIUMPH-3.

What the TRIUMPH program is (design features reported)

The TRIUMPH program is described as a registrational Phase 3 clinical-development program consisting of four multicenter, randomized, double‑blind trials that evaluate weekly subcutaneous retatrutide versus placebo in conjunction with healthy diet and physical activity across indications including weight management and nested protocols for obstructive sleep apnea (OSA) and knee osteoarthritis (OA); the program is planned to enroll over 5,800 participants and permits independent analyses of weight management, OSA, and OA with type I error control (α = 0.05, split between the overarching weight-management and each basket trial). [S4]

Which TRIUMPH endpoints and populations were specified in the reviewed design paper

The TRIUMPH weight-management primary endpoint is percent change in body weight; the OSA primary endpoint is change in Apnea‑Hypopnea Index; the knee‑OA primary endpoint is the WOMAC pain subscale score. TRIUMPH includes two weight‑management basket trials (TRIUMPH‑1 and TRIUMPH‑2) with OSA and OA protocols nested, one weight‑management trial in a population with cardiovascular disease (TRIUMPH‑3), and a stand‑alone OA trial (TRIUMPH‑4). [S4]

Phase 2 evidence that informed TRIUMPH dose selection and expectations

A 48‑week Phase 2 randomized, double‑blind, placebo‑controlled obesity trial of retatrutide (multiple subcutaneous once‑weekly dose arms including 1 mg, 4 mg, 8 mg and 12 mg with specified starting‑dose escalation schedules) reported dose‑dependent weight reductions at 24 and 48 weeks (primary end point at 24 weeks) and dose‑related gastrointestinal adverse events and transient increases in heart rate; these Phase 2 data were used to inform Phase 3 dose selection. [S1]

A Phase 2 randomized, double‑blind, placebo‑ and active‑controlled trial in people with type 2 diabetes tested multiple retatrutide maintenance doses (including 0.5 mg, 4 mg, 8 mg, and 12 mg with various escalation schedules) versus placebo and an active GLP‑1 comparator, with primary HbA1c assessment at 24 weeks and additional efficacy measures at 36 weeks; outcomes showed dose‑dependent HbA1c and weight reductions and a gastrointestinal adverse‑event profile consistent with incretin agonists. [S5]

A randomized Phase 2a substudy in participants with metabolic dysfunction‑associated steatotic liver disease assessed once‑weekly subcutaneous retatrutide (1, 4, 8 or 12 mg) versus placebo over 48 weeks, reporting substantial, dose‑related reductions in liver fat at 24 weeks and relationships between liver‑fat change and weight and metabolic measures. [S7]

Phase 3 evidence present in the reviewed sources (non‑TRIUMPH) and status of TRIUMPH results

Among reviewed Phase 3 material, a completed Phase 3 trial named TRANSCEND‑T2D‑1 (a 40‑week, randomized, double‑blind, placebo‑controlled study of once‑weekly subcutaneous retatrutide at 4 mg, 9 mg, or 12 mg versus placebo in adults with type 2 diabetes inadequately controlled by diet and exercise) is reported with efficacy and safety results in the reviewed sources, showing dose‑dependent HbA1c and bodyweight reductions at week 40 and a generally mild‑to‑moderate gastrointestinal adverse‑event profile. [S8]

The reviewed TRIUMPH design article outlines the planned trials and endpoints but does not present TRIUMPH‑1, TRIUMPH‑2, or TRIUMPH‑3 outcome data; the reviewed sources do not include peer‑reviewed full results for TRIUMPH‑1, TRIUMPH‑2, or TRIUMPH‑3. [S4]

Implications for interpreting the current evidence base

Phase 2 trials documented substantial, dose‑related metabolic effects of retatrutide (weight loss, HbA1c reductions, liver‑fat reductions) and dose‑related gastrointestinal adverse events that informed Phase 3 design; a separate Phase 3 trial (TRANSCEND‑T2D‑1) reported dose‑dependent efficacy and an adverse‑event profile consistent with incretin agonists in people with type 2 diabetes. However, the TRIUMPH‑specific Phase 3 trial results (TRIUMPH‑1, TRIUMPH‑2, TRIUMPH‑3) are not reported in the reviewed sources, so trial‑level TRIUMPH efficacy and safety outcomes cannot be summarized from these materials. [S1] [S5] [S7] [S8] [S4]

Reported study-design details from cited sources

The following table summarizes protocol details reported in cited studies. These details are provided as literature context only and are not recommendations or instructions.

Source Study Type Model / Subject Amount Reported Route Reported Frequency Duration Notes
[S1] Randomized, double‑blind, placebo‑controlled Phase 2 clinical trial Adults with obesity (BMI ≥30 or 27– 1 mg; 4 mg (initial dose 2 mg or 4 mg); 8 mg (initial dose 2 mg or 4 mg); 12 mg (initial dose 2 mg); placebo subcutaneous once weekly 48 weeks Primary end point: percent change in body weight at 24 weeks; multiple dose arms and starting‑dose escalation schedules were randomized; safety assessed through 48 weeks.
[S5] Randomized, double‑blind, double‑dummy, placebo‑ and active‑controlled Phase 2 clinical trial Adults with type 2 diabetes (HbA1c 7.0–10.5%, BMI 25–50 kg/m2) 0.5 mg; 4 mg (starting dose 2 mg and no escalation variants); 8 mg (starting dose 2 mg and starting dose 4 mg variants); 12 mg (starting dose 2 mg); placebo; 1.5 mg dulaglutide (active comparator) subcutaneous once weekly 36 weeks (efficacy assessed at 24 and 36 weeks) Primary endpoint: change in HbA1c at 24 weeks; included an active comparator (dulaglutide 1.5 mg). Safety assessed across dose groups.
[S7] Randomized, double‑blind, placebo‑controlled Phase 2a trial (substudy of the 48‑week obesity trial) Participants with metabolic dysfunction‑associated steatotic liver disease and ≥10% liver fat 1 mg; 4 mg; 8 mg; 12 mg; placebo subcutaneous once weekly 48 weeks Primary objective of substudy: mean relative change in liver fat at 24 weeks; n=98 randomized to retatrutide dose arms or placebo.
[S8] Randomized, double‑blind, placebo‑controlled Phase 3 clinical trial (TRANSCEND‑T2D‑1) Adults with type 2 diabetes inadequately controlled with diet and exercise (HbA1c 7.0–9.5%, BMI ≥23 kg/m2) 4 mg; 9 mg; 12 mg; placebo subcutaneous once weekly 40 weeks Primary endpoint: change in HbA1c at week 40; key secondary endpoint: percent change in bodyweight at week 40; trial enrolled 537 participants and reported dose‑dependent HbA1c and weight reductions.
[S4] Phase 3 multicenter randomized, double‑blind trials (TRIUMPH program; design paper) Adults with obesity and related complications (OSA and/or knee OA) and a CVD subset across the program not reported in the reviewed source subcutaneous weekly not reported in the reviewed source TRIUMPH consists of two weight‑management basket trials (TRIUMPH‑1, TRIUMPH‑2) with nested OSA and OA protocols, one weight‑management trial in a population with CVD (TRIUMPH‑3), and a stand‑alone OA trial (TRIUMPH‑4). Primary endpoints: percent change in body weight (weight management), change in Apnea‑Hypopnea Index (OSA), and WOMAC pain subscale score (knee OA).

Limitations and research gaps

  • No peer‑reviewed or sponsor‑reported full results for TRIUMPH‑1, TRIUMPH‑2, or TRIUMPH‑3 are contained in the reviewed source set; TRIUMPH is described in a design/planned‑trial paper but outcome data for those specific trials are not present in the reviewed excerpts.
  • Some reviewed evidence is from Phase 2 trials and from a non‑TRIUMPH Phase 3 trial (TRANSCEND‑T2D‑1); cross‑trial comparisons have limitations and differences in population, endpoints, dose regimens, and duration.
  • Reported Phase 2 and TRANSCEND‑T2D‑1 findings inform expectations but are not substitutes for the actual TRIUMPH trial results; dose, duration, and safety outcomes for TRIUMPH‑1/2/3 remain 'not reported in the reviewed source.'

Documentation checklist

  • Confirm whether TRIUMPH-1, TRIUMPH-2, and TRIUMPH-3 full results have been posted as peer‑reviewed publications.
  • If reviewing a TRIUMPH report, verify: primary endpoint definition, statistical estimand, sample size and randomized arms, doses tested, treatment duration, and pre-specified safety monitoring results.
  • Compare reported TRIUMPH outcomes to phase 2 benchmarks (weight-change, glycaemic, and liver‑fat endpoints) using matched timepoints and dose arms.
  • Inspect adverse-event tables for frequency and severity by system-organ class (gastrointestinal, cardiovascular, metabolic, others) and for discontinuations.
  • Look for pre-specified analyses for cardiac rate changes, hepatic outcomes, and subgroup analyses (OSA, osteoarthritis, CVD) described in the TRIUMPH protocol.
  • ClinicalTrials.gov registry record printouts for TRIUMPH trials (protocol identifiers and updates)
  • Sponsor trial protocol synopsis and statistical analysis plan (PDF copies)
  • Central laboratory sample tracking and cold‑chain temperature logs
  • Study document version control logs and site monitoring visit summaries
  • Laboratory specimen labeling supplies and storage inventory logs

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More Retatrutide research

Sources and references

  1. [S1] Jastreboff AM, Kaplan LM, Frías JP, Wu Q, Du Y, Gurbuz S. Triple-Hormone-Receptor Agonist Retatrutide for Obesity – A Phase 2 Trial.. The New England journal of medicine. 2023. PMID: 37366315. DOI: 10.1056/NEJMoa2301972
  2. [S2] Drucker DJ. Efficacy and Safety of GLP-1 Medicines for Type 2 Diabetes and Obesity.. Diabetes care. 2024. PMID: 38843460. DOI: 10.2337/dci24-0003
  3. [S3] Katsi V, Koutsopoulos G, Fragoulis C, Dimitriadis K, Tsioufis K. Retatrutide-A Game Changer in Obesity Pharmacotherapy.. Biomolecules. 2025. PMID: 40563436. DOI: 10.3390/biom15060796
  4. [S4] Giblin K, Kaplan LM, Somers VK, Le Roux CW, Hunter DJ, Wu Q. Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials.. Diabetes, obesity & metabolism. 2026. PMID: 41090431. DOI: 10.1111/dom.70209
  5. [S5] Rosenstock J, Frias J, Jastreboff AM, Du Y, Lou J, Gurbuz S. 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.. Lancet (London, England). 2023. PMID: 37385280. DOI: 10.1016/S0140-6736(23)01053-X
  6. [S6] Kokkorakis M, Chakhtoura M, Rhayem C, Al Rifai J, Ghezzawi M, Valenzuela-Vallejo L. Emerging pharmacotherapies for obesity: A systematic review.. Pharmacological reviews. 2025. PMID: 39952695. DOI: 10.1124/pharmrev.123.001045
  7. [S7] Sanyal AJ, Kaplan LM, Frias JP, Brouwers B, Wu Q, Thomas MK. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial.. Nature medicine. 2024. PMID: 38858523. DOI: 10.1038/s41591-024-03018-2
  8. [S8] Bajaj HS, Welch M, Shah P, Luna E, Jaouimaa FZ, Liu B. Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a double-blind, randomised, phase 3 trial.. Lancet (London, England). 2026. PMID: 42250575. DOI: 10.1016/S0140-6736(26)00967-0

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