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
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: Retatrutide and Tirzepatide in MASLD/MASH
Master protocol evaluating both retatrutide and tirzepatide vs placebo for prevention of Major Adverse Liver Outcomes (MALO) in high-risk MASLD.
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: Type 2 Diabetes Glycemic Control Trial
Pivotal Phase 3 trial evaluating retatrutide for glycemic control in adults with type 2 diabetes inadequately controlled on metformin, assessing HbA1c reduction and 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.
TRIUMPH-1
TRIUMPH-1: Phase 3 Pivotal Obesity Trial of Retatrutide
The pivotal Phase 3 trial evaluating retatrutide for the treatment of obesity and overweight in adults, part of the TRIUMPH (Triple Receptor Agonist Intervention Utilizing Metabolic Pathways in Health) 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
Phase 2 Obesity Trial of Retatrutide (NCT04881706)
A 48-week, randomized, double-blind, placebo-controlled, dose-ranging Phase 2 trial evaluating retatrutide in adults with obesity or overweight, demonstrating up to 24.2% mean weight loss at the highest dose.
First-in-Human Study
Phase 1 First-in-Human Study of Retatrutide (LY3437943)
The first clinical study of retatrutide in humans, evaluating safety, tolerability, and pharmacokinetics in single and multiple ascending dose cohorts of healthy volunteers and patients with type 2 diabetes.