Clinical Trials
Retatrutide (LY3437943) is being evaluated in 19 clinical trials across three Phase 3 programs — TRIUMPH (obesity), TRANSCEND (type 2 diabetes), and SYNERGY (MASLD/MASH). The first Phase 3 results (TRIUMPH-4) reported 28.7% weight loss in December 2025, with 6+ additional readouts expected in 2026.
Development Program Overview
Eli Lilly's retatrutide program spans three Phase 3 families: TRIUMPH (obesity/weight management), TRANSCEND (type 2 diabetes), and SYNERGY (MASLD/MASH liver disease). TRIUMPH-4 delivered the first Phase 3 readout in December 2025, showing 28.7% weight loss at 12 mg/68 weeks. Multiple additional Phase 3 results and regulatory submissions are expected throughout 2026.
Development Timeline
All Trials
TRIUMPH-1
TRIUMPH-1: Phase 3 Pivotal Obesity Trial of Retatrutide (Results-Published)
The pivotal Phase 3 obesity trial of retatrutide. Topline results announced May 21, 2026: 28.3% mean weight loss at 12 mg over 80 weeks (n=2,339 adults with obesity or overweight + at least one weight-related comorbidity, no diabetes). All three doses met primary and key secondary endpoints. The largest pivotal weight-loss readout in the retatrutide program to date.
Retatrutide Dose Escalation Optimization
Phase 3b Dosing Optimization Study for Retatrutide
Investigating different retatrutide dose escalation schemes to optimize efficacy-tolerability balance.
SYNERGY-OUTCOMES
SYNERGY-OUTCOMES Trial: Retatrutide for Liver Disease (MASH)
SYNERGY-OUTCOMES is a Phase 3 trial testing retatrutide and tirzepatide vs placebo to prevent major adverse liver outcomes in high-risk MASLD/MASH. What it studies.
TRANSCEND-T2D-2
TRANSCEND-T2D-2: Retatrutide vs Semaglutide
Head-to-head comparison of retatrutide vs semaglutide in adults with T2D inadequately controlled on metformin +/- SGLT2 inhibitor.
TRIUMPH-4
TRIUMPH-4: Obesity with Knee Osteoarthritis (First Phase 3 Readout)
The first Phase 3 trial of retatrutide to report results, evaluating weight loss and knee osteoarthritis pain reduction in adults with obesity and knee OA. Demonstrated 28.7% weight loss and 75% pain reduction at 12 mg/68 weeks.
Phase 1 Japan Study
Phase 1 Study in Japanese Subjects (NCT06003465)
A Phase 1 study evaluating the safety, tolerability, and pharmacokinetics of retatrutide in Japanese adults with overweight or obesity, supporting global regulatory submissions including Japan (PMDA).
Phase 2 Body Composition Substudy
Phase 2 Body Composition Substudy
A substudy of the Phase 2 obesity trial evaluating the effects of retatrutide on body composition using dual-energy X-ray absorptiometry (DXA), assessing changes in fat mass, lean mass, and visceral adipose tissue.
Phase 2 CKD Trial
Phase 2 Chronic Kidney Disease Trial (NCT05936151)
A Phase 2 trial evaluating retatrutide in adults with chronic kidney disease (CKD) and overweight or obesity, assessing effects on kidney function, body weight, and metabolic parameters.
Phase 2 MASLD Substudy
Phase 2 MASLD/MASH Substudy (Liver Fat Analysis)
A pre-specified substudy of the Phase 2 obesity trial evaluating the effects of retatrutide on hepatic fat content using MRI-PDFF in participants with metabolic dysfunction-associated steatotic liver disease (MASLD).
TRANSCEND-T2D-1
TRANSCEND-T2D-1: Phase 3 Type 2 Diabetes Trial (Results-Published)
Pivotal Phase 3 trial of retatrutide in adults with type 2 diabetes (n=537, 40 weeks). Full results published in The Lancet on June 6, 2026 and presented at ADA 2026: HbA1c reductions up to 1.94 percentage points and weight loss up to 15.3% at 12 mg — glycemic control comparable to tirzepatide with substantially greater weight loss.
TRIUMPH-3
TRIUMPH-3: Phase 3 Weight Management in Cardiovascular Disease
Phase 3 trial evaluating retatrutide for weight management in adults with Class II/III obesity (BMI ≥35) and established cardiovascular disease, with and without type 2 diabetes.
TRIUMPH-Outcomes
TRIUMPH-Outcomes: Cardiovascular Outcomes Trial (CVOT)
Large-scale cardiovascular outcomes trial evaluating whether retatrutide reduces major adverse cardiovascular events (MACE) in adults with overweight/obesity and established cardiovascular disease.
TRIUMPH-2
TRIUMPH-2: Phase 3 Weight Management in Type 2 Diabetes
Phase 3 trial evaluating retatrutide for weight management in adults with obesity or overweight (BMI ≥27) AND type 2 diabetes, with a nested obstructive sleep apnea (OSA) basket. Part of the TRIUMPH development program.
Phase 2 Type 2 Diabetes Trial
Phase 2 Type 2 Diabetes Trial of Retatrutide (NCT04867785)
A 36-week, randomized, double-blind, placebo- and active-comparator-controlled Phase 2 trial evaluating retatrutide in adults with type 2 diabetes, demonstrating potent HbA1c reductions and significant weight loss.
Phase 1b MAD Trial
Phase 1b Multiple Ascending Dose Trial (NCT04143802)
A Phase 1b, randomized, double-blind, placebo-controlled, multiple-ascending dose trial evaluating safety, tolerability, pharmacokinetics, and pharmacodynamics of retatrutide in adults with type 2 diabetes.
Phase 2 Obesity Trial
Retatrutide Phase 2 Obesity Trial: -24.2% Weight Loss
In the Phase 2 obesity trial (n=338), retatrutide produced up to -24.2% mean weight loss at 12 mg over 48 weeks. The headline result, doses, and safety data.
First-in-Human Study
Retatrutide Phase 1 Trial: First Human Study (2019)
Retatrutide entered its first-in-human Phase 1 trial in 2019, confirming a ~6-day half-life that enables once-weekly dosing. Safety, pharmacokinetics, and early findings.