Retatrutide Clinical Trials

Overview of the Retatrutide Clinical Trial Program

Retatrutide (development code LY3437943) is an investigational agent sponsored by Eli Lilly and Company. It functions as a GLP-1 / GIP / Glucagon receptor agonist, targeting three distinct metabolic hormone pathways simultaneously. For scientific background on this mechanism, see the [triple agonism mechanism review](/news/triple-agonism-mechanism-review).

As an investigational drug in Phase 3 development, retatrutide has not received regulatory approval and is not commercially available. Clinical research protocols are structured across two primary trial series: the TRIUMPH clinical trials, which evaluate weight management and related chronic conditions, and the TRANSCEND clinical trials, which investigate glycemic management in type 2 diabetes mellitus. Readers can follow broader updates via the [retatrutide clinical trial tracker](/retatrutide/clinical-trials) and the [regulatory pathway outlook](/news/regulatory-pathway-outlook).

Phase 3 TRIUMPH Clinical Trials

The TRIUMPH clinical development program assesses retatrutide in populations with obesity, overweight, and associated complications, including knee osteoarthritis, obstructive sleep apnea, atherosclerotic cardiovascular disease (ASCVD), and chronic kidney disease (CKD). A dedicated summary of these studies is available in the [retatrutide obesity trials guide](/guides/retatrutide-obesity-trials).

TRIUMPH-1 (NCT05929066)

[TRIUMPH-1](/trials/triumph-1) evaluated retatrutide in 2,335 adults with obesity, overweight, knee osteoarthritis, and obstructive sleep apnea. Participants received either retatrutide or placebo. The trial recorded a study start date of 2023-07-10, with a primary completion date of 2026-04-06, and its recruitment status is listed as Completed. Primary endpoints include:

• Percent Change From Baseline in Body Weight
• Change from Baseline in Apnea-Hypopnea Index (AHI) Events Per Hour for GSA1 Subset
• Change from Baseline in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain Subscale Score for GOA1 Subset
• Percent Change from Baseline in Body Weight in Participants in Extension Subset

Additional operational updates are documented in the [TRIUMPH-1 readout report](/news/triumph-1-topline-readout).

TRIUMPH-4 (NCT05931367)

TRIUMPH-4 evaluated retatrutide compared to placebo in 445 participants with obesity, overweight, and knee osteoarthritis. The study commenced on 2023-08-01, with a primary completion date of 2025-11-14, and holds a status of Completed. Primary endpoints measured are:

• Change from Baseline in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain Subscale Score
• Percent Change from Baseline in Body Weight

TRIUMPH-5 (NCT06662383)

TRIUMPH-5 is an active, not recruiting Phase 3 trial with an enrolment of 800 participants living with obesity. The trial evaluates retatrutide against the active comparator tirzepatide. The study started on 2024-11-01, with an estimated primary completion date of 2026-11-01. The primary endpoint is Percent Change from Baseline in Body Weight.

TRIUMPH-9 (NCT07357415)

[TRIUMPH-9](/trials/triumph-9-nct07357415) is an active, not recruiting Phase 3 study enrolling 600 participants with obesity or overweight. The study start date is 2026-01-24, and the primary completion date is 2028-10-01. The intervention is Drug: Retatrutide, and the primary endpoint is Percent Change from Baseline in Body Weight.

TRIUMPH-Outcomes (NCT06383390)

[TRIUMPH-Outcomes](/trials/triumph-outcomes) is a long-term cardiovascular and renal outcome trial enrolling 10,000 adults living with obesity, atherosclerotic cardiovascular disease (ASCVD), and chronic kidney disease (CKD). The study compares retatrutide against placebo. It commenced on 2024-04-30, with a primary completion date of 2029-02-01, and is listed as Active, not recruiting. The primary outcome measures are:

• Time to First Occurrence of Composite Endpoints
• Time to First Occurrence of Composite Endpoint of End Stage Kidney Disease (ESKD), ≥ 40% Sustained Decline in Estimated Glomerular Filtration Rate (eGFR), CV Death or Renal Death

Phase 3 TRANSCEND Clinical Trials

The TRANSCEND program investigates retatrutide in adult patients diagnosed with type 2 diabetes mellitus. More detail on this program can be found in the [retatrutide diabetes trials guide](/guides/retatrutide-diabetes-trials).

TRANSCEND-T2D-1 (NCT06354660)

TRANSCEND-T2D-1 evaluated retatrutide compared with placebo in 537 adult participants with type 2 diabetes and inadequate glycemic control managed with diet and exercise alone. The study began on 2024-04-10, reached primary completion on 2026-01-22, and is listed as Completed. The primary endpoint is Change from Baseline in Hemoglobin A1c (HbA1c) (%).

TRANSCEND-T2D-2 (NCT06260722)

TRANSCEND-T2D-2 is an active, not recruiting Phase 3 trial enrolling 1,250 adult participants with type 2 diabetes and inadequate glycemic control on metformin with or without an SGLT2 inhibitor. The trial evaluates retatrutide against an active comparator, semaglutide. Study initiation occurred on 2024-02-21, with primary completion expected on 2026-08-01. The primary endpoint is Change from Baseline in Hemoglobin A1c (HbA1c) (%).

Expanded Access Protocol

Eli Lilly and Company sponsors an expanded access program under identifier [NCT07629401](/trials/pre-approval-expanded-access-of-retatrutide-ly3437943-nct07629401), titled "Pre-approval Expanded Access of Retatrutide (LY3437943)". The protocol status is Available, covering indications of Obesity and Obesity-related Complications with the intervention Drug: Retatrutide.

Clinical Trial Summary Table

Sources

• Eli Lilly and Company. Clinical trial protocol NCT05929066 (TRIUMPH-1).
• Eli Lilly and Company. Clinical trial protocol NCT05931367 (TRIUMPH-4).
• Eli Lilly and Company. Clinical trial protocol NCT06662383 (TRIUMPH-5).
• Eli Lilly and Company. Clinical trial protocol NCT07357415 (TRIUMPH-9).
• Eli Lilly and Company. Clinical trial protocol NCT06383390 (TRIUMPH-Outcomes).
• Eli Lilly and Company. Clinical trial protocol NCT06354660 (TRANSCEND-T2D-1).
• Eli Lilly and Company. Clinical trial protocol NCT06260722 (TRANSCEND-T2D-2).
• Eli Lilly and Company. Clinical trial protocol NCT07629401 (Pre-approval Expanded Access of Retatrutide).