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Investigational triple agonist of GIP, GLP-1 and glucagon receptors

Retatrutide — evidence

What has been published, classified by the kind of document it is. This is not a protocol, not a score, and not a recommendation for use.

Evidence overview

2 records in this file

  • CLINICAL TRIAL2

Research areas. Investigational-drug Phase 2; Investigational-drug Phase 3.

Publication span. 2023–2026.

What we know

  • Jastreboff et al. 2023 (NEJM) is a published Phase 2 obesity trial of investigational retatrutide.
  • Lilly has issued Phase 3 TRIUMPH-1 topline disclosures. Those are sponsor communications, not a peer-reviewed paper and not an approval.
  • No Drugs@FDA approved product as of this review. Not interchangeable with semaglutide or tirzepatide.

Editorial reading of the records below, labelled as Therapept analysis. How records are built

What remains uncertain

  • The full peer-reviewed TRIUMPH clinical package, including estimands and adverse-event tables.
  • Whether, and when, FDA will license a product — a Phase 3 topline is not a listing decision.

Regulatory notes

Investigational

  • No approved United States product in Drugs@FDA as of this review.
  • CAS 2381089-83-2 is the identifier used in DrugBank and related registries.
  • A Phase 2 obesity trial is published in NEJM (2023). Sponsor Phase 3 topline disclosures in the TRIUMPH programme are not a listing decision and are not an approved label.
  • Not interchangeable with semaglutide or tirzepatide, which have different receptor profiles and approved products.

Regulatory status describes how a substance is classified. It is not a safety assessment of any particular material.

Studies and documents

  1. CLINICAL TRIAL2026Sponsor Phase 3 topline disclosure

    Lilly's triple agonist, retatrutide, delivered powerful weight loss in pivotal Phase 3 obesity trial (TRIUMPH-1 topline)

    Eli Lilly and CompanyCompany news release

    Population
    Adults with obesity or overweight and at least one weight-related comorbidity, without diabetes, in TRIUMPH-1
    Sample
    2,339 randomised per the sponsor release; 2,335 actual enrolment on ClinicalTrials.gov (NCT05929066)
    Objective
    To disclose topline Phase 3 body-weight results for retatrutide in TRIUMPH-1.
    Endpoint investigated
    Percent change in body weight at 80 weeks as reported by the sponsor

    Study design

    Registry
    NCT05929066

    This describes the published study design. It is not a usage or dosing recommendation.

    In May 2026 Lilly disclosed topline TRIUMPH-1 results. The release reports that the 4 mg, 9 mg and 12 mg once-weekly arms met primary and key secondary endpoints, with a stated 80-week mean body-weight change of 28.3% at 12 mg under the efficacy estimand. The disclosure is a sponsor communication, not a peer-reviewed paper, and retatrutide remains investigational.

    Limitations. Topline company disclosure. Estimands, full adverse-event tables and the statistical analysis plan are not independently reproduced here. A peer-reviewed TRIUMPH-1 paper was not identified at review. Not an FDA approval.

    Eli Lilly — TRIUMPH-1 topline news release (May 2026) — Registry record: ClinicalTrials.gov NCT05929066 (Phase 3, completed).Reviewed 15 September 2026

  2. CLINICAL TRIAL2023Randomised, double-blind, placebo-controlled Phase 2 trial

    Triple-hormone-receptor agonist retatrutide for obesity — a Phase 2 trial

    Jastreboff AM, Kaplan LM, Frías JP, Wu Q, Du Y, Gurbuz S, Coskun T, Haupt A, Milicevic Z, Hartman ML; Retatrutide Phase 2 Obesity Trial InvestigatorsNew England Journal of Medicine

    Population
    Adults with obesity in a registered Phase 2 programme
    Sample
    n = 338
    Objective
    To test once-weekly retatrutide versus placebo for body-weight change over 48 weeks.
    Endpoint investigated
    Body-weight change and related endpoints in Phase 2

    Study design

    Phase
    Phase 2
    Duration
    48 weeks, with the primary endpoint at week 24
    Intervention, as the source describes it
    Once-weekly subcutaneous retatrutide at several dose levels and starting-dose schedules
    Comparator
    Placebo
    Primary endpoint
    Percentage change in body weight from baseline to week 24
    Registry
    NCT04881760

    This describes the published study design. It is not a usage or dosing recommendation.

    Phase 2 randomised trial of investigational retatrutide, a GIP/GLP-1/glucagon receptor agonist, versus placebo in adults with obesity. Primary results were published in NEJM. This is investigational-drug evidence under medical supervision — not research-chemical catalogue evidence, and not an approved-product label.

    Limitations. Phase 2. Product, dose and supervision are those of the sponsor programme. Findings do not transfer to unapproved look-alike products, and they do not make retatrutide interchangeable with semaglutide or tirzepatide.

    DOI 10.1056/NEJMoa2301972Jastreboff et al., N Engl J Med (2023)Reviewed 12 September 2026

Last reviewed 12 September 2026 · Compiled by Therapept Editorial · How these records are built