Retatrutide FDA approval timeline: trial readouts, BLA filing and decision window

Retatrutide is not FDA approved for any use. It is an investigational once-weekly triple agonist (GIP, GLP-1 and glucagon receptors) from Eli Lilly, and its strongest evidence is a set of phase 3 randomized trials. Lilly says it plans to submit a Biologics License Application (BLA) to the FDA in the first quarter of 2027 (Lilly, 2026-07-23). Under FDA’s standard review goals, a decision would then be due about 12 months after submission, which points to early 2028; a priority review would bring that to late 2027. No approval date has been announced, and outside clinical trials retatrutide cannot be obtained legally in the US.

Item	Status
US FDA status	Investigational; not approved for any use. No marketing application filed yet
Next regulatory step	BLA submission planned for Q1 2027 (Lilly Q2 2026 results, 2026-08-05); no PDUFA date exists until FDA files the application
Compounding (503A/503B)	Not allowed: FDA says retatrutide “cannot be used in compounding under federal law” (FDA, current as of 2026-09-01)
WADA 2026	Prohibited at all times under S0 Non-approved substances, which covers drugs still in clinical development (WADA 2026 List)
Strongest evidence	Human RCT, phase 3 (TRIUMPH-1, n=2,339, NEJM 2026)
Human trials	14 phase 3 records on ClinicalTrials.gov; 5 completed, including NCT05929066 and NCT05931367
Last checked	2026-10-24

What changed (October 2026): the appeals court that heard Lilly’s classification case has asked both sides whether it can hear the appeal at all; Lilly has sued US sellers of illegal retatrutide; and the sleep apnea trials are now published in full. No application has been filed yet. On 2026-10-28 Lilly reported its first head-to-head phase 3 result, against Ozempic 2 mg in type 2 diabetes (Lilly), and its third-quarter report on 2026-10-29 gave no new filing date (Lilly Q3 2026).

Retatrutide FDA approval timeline: what has happened so far

The dates below come from trial registrations, journal publications, FDA and Lilly’s own announcements. Lilly-reported weight-loss figures in press releases often use the “efficacy estimand” (people who stayed on treatment); the published papers lead with the more conservative treatment-regimen estimand, which counts everyone randomized. Both are shown where they differ.

Date	Milestone	Source
2019	First-in-human single-dose safety study completed (n=45)	NCT03841630
2023-06-26	Phase 2 obesity trial (n=338) and phase 2 type 2 diabetes trial (n=281) published	NEJM; Lancet
2023-07	TRIUMPH-2 begins enrolling (phase 3 program under way)	Lancet 2026
2024-09-03	Lilly sues FDA over classifying retatrutide as a drug rather than a biological product	S.D. Indiana, No. 1:24-cv-01503
2025-09-30	District court upholds FDA’s protein definition but sets aside its “analogous to a protein” finding and sends it back to FDA	S.D. Indiana
2025-12-11	First phase 3 topline: TRIUMPH-4 (knee osteoarthritis, n=445)	Lilly
2026-05-21	TRIUMPH-1 topline (obesity, with sleep apnea and knee pain sub-studies)	Lilly
2026-06-05	Pre-approval expanded-access record posted	NCT07629401
2026-06-06	TRANSCEND-T2D-1 (type 2 diabetes, n=537) published	Lancet
2026-07-23	TRIUMPH-2 and TRIUMPH-3 topline; BLA target set at Q1 2027	Lilly
2026-08-05	Q2 results repeat the Q1 2027 BLA plan	Lilly
2026-08-12	Lilly files six lawsuits against US sellers of illegal retatrutide and reports more than 14,000 listings and posts in over 100 countries for removal	Lilly
2026-08-24	FDA warning letters treat a “GLP-3R” product sold as a research peptide as unapproved retatrutide	FDA
2026-09-24	Seventh Circuit hears Lilly’s appeal on the drug-or-biologic question, then orders extra briefs on whether it has jurisdiction (filed 2026-10-08)	Seventh Circuit docket No. 26-1301
2026-09-29	TRIUMPH-1 published in NEJM; TRIUMPH-2 published in The Lancet	PubMed
2026-10-21	Dedicated sleep-apnea trials published in full: TRIUMPH-1-OSA (n=243) and a second, previously unreported trial, TRIUMPH-2-OSA (n=448, with type 2 diabetes)	PubMed
2026-10-28	TRANSCEND-T2D-2 topline: in 1,298 adults with type 2 diabetes, retatrutide lowered A1C and weight more than Ozempic 2 mg over 80 weeks (first head-to-head phase 3 result)	Lilly
2026-10-29	Q3 2026 results list the TRANSCEND-T2D-2 result; no new US filing date given	Lilly
Q1 2027	Planned BLA submission (not yet happened)	Lilly

What the phase 3 trials found

The results behind the filing are encouraging. In TRIUMPH-1, adults with obesity and without diabetes lost a mean 17.6%, 23.7% and 25.0% of body weight on the three retatrutide doses over 80 weeks, against 3.9% on placebo [Human RCT, n=2,339] (Jastreboff et al., NEJM 2026). The same trial met its knee-pain and sleep-apnea goals: pain scores fell more than with placebo in 574 people with knee osteoarthritis, and apnea-hypopnea events fell by about 22 to 25 events per hour more than with placebo on the 9 mg and 12 mg doses in 243 people with obstructive sleep apnea [Human RCT, n=243] (Grunstein et al., NEJM 2026). A matching trial in 448 people who also had type 2 diabetes found about 14 to 15 fewer events per hour than placebo on the same doses [Human RCT, n=448]. Lilly’s press release, using the efficacy estimand, reported 28.3% at the highest dose.

In people with type 2 diabetes, TRIUMPH-2 found weight loss of 11.9% to 18.8% versus 5.1% on placebo at 80 weeks [Human RCT, n=1,152] (Lancet 2026). TRANSCEND-T2D-1, a 40-week diabetes trial, lowered HbA1c (a three-month blood sugar average) by 1.69 to 1.94 percentage points versus 0.81 on placebo, from a baseline of 7.9% [Human RCT, n=537] (Bajaj et al., Lancet 2026).

Three trials are reported so far only in Lilly releases. TRIUMPH-3, in 1,946 adults (registry enrollment) with severe obesity and established cardiovascular disease, reported 22.6% weight loss at the highest dose versus 3.2% on placebo at 80 weeks [Human RCT, topline] (Lilly, 2026-07-23). TRIUMPH-4, in 445 adults with obesity and knee osteoarthritis, reported up to 28.7% weight loss at 68 weeks and a 4.5-point drop in WOMAC pain score [Human RCT, topline] (Lilly, 2025-12-11). TRANSCEND-T2D-2, an open-label trial in 1,298 adults with type 2 diabetes on metformin (with or without an SGLT2 inhibitor), compared retatrutide 9 mg and 12 mg with Ozempic 2 mg, Ozempic’s highest approved dose. At 80 weeks, from a baseline of 8.3%, HbA1c fell 2.2 points on both retatrutide doses versus 1.8 on Ozempic, and weight fell 19.5% and 20.9% versus 9.4% [Human RCT, topline, n=1,298] (Lilly, 2026-10-28). These are efficacy-estimand figures (people who stayed on treatment); Lilly has not released the treatment-regimen figures. Superiority on HbA1c was formally shown for 12 mg; for 9 mg it was nominal only. Topline figures have not yet been through peer review.

What a PDUFA date is and how the FDA review clock runs

PDUFA is the Prescription Drug User Fee Act. Under it, companies pay fees and FDA commits to review goals. For a new molecular entity or an original BLA, FDA first spends 60 days deciding whether to file (accept) the application; the review clock then starts. FDA’s goal is to “review and act on 90 percent” of standard applications within 10 months of that 60-day filing date, and priority applications within 6 months (FDA, PDUFA VII commitment letter). The date that clock produces is what companies call the “PDUFA date”.

A PDUFA date is a goal, not a guarantee. On or before it, FDA either approves the application or sends a complete response letter that lists the deficiencies to fix. A major amendment submitted during review can extend the goal date by three months. By day 74, FDA tells the sponsor its planned review timeline and whether it expects to hold an advisory committee meeting. The current PDUFA VII goals cover fiscal years 2023 through 2027, so a review running into 2028 would fall under whatever reauthorization follows.

Priority review applies to drugs that could be a significant improvement in treating a serious condition; FDA’s stated goal is action within 6 months instead of 10 (FDA, Priority Review). None of the Lilly announcements cited here says whether Lilly will request priority review for retatrutide.

Realistic decision window for retatrutide

The windows below are arithmetic from FDA’s published goals applied to Lilly’s stated submission quarter. They are estimates, not Lilly or FDA statements, and they assume the application is filed without delay.

Review path	FDA goal	If submitted Jan–Mar 2027
Standard review	60-day filing + 10 months	Jan–Mar 2028
Priority review	60-day filing + 6 months	Sep–Nov 2027
Standard + major amendment	Goal date + 3 months	Apr–Jun 2028
National priority voucher	1–2 month target	Feb–May 2027 (no voucher announced)

The last row is a possibility rather than a forecast. FDA’s Commissioner’s National Priority Voucher pilot targets a 1–2 month review instead of the usual 6 months or more (FDA, CNPV program). Lilly’s oral obesity drug orforglipron (Foundayo) was approved under that program on 2026-04-01, 50 days after filing and 294 days before its PDUFA date (FDA, 2026-04-01). No FDA or Lilly announcement of a voucher for retatrutide had been published at the last check.

Approval, if it comes, would cover the indications Lilly files for: Lilly names obesity, knee osteoarthritis pain and obstructive sleep apnea as supported by the current data. Approval for type 2 diabetes is a separate question, and the long-term heart and kidney outcomes trial, TRIUMPH-Outcomes (n=10,000), has a primary completion date of 2029-02 (NCT06383390).

Why the application is a BLA and not an NDA

Peptides of 40 or fewer amino acids are usually regulated as drugs through a New Drug Application (NDA). Since 2020, FDA’s rule defines a “protein”, and therefore a biological product approved through a BLA, as “any alpha amino acid polymer with a specific, defined sequence that is greater than 40 amino acids in size” (Federal Register, 2020-02-21). Retatrutide has a 39-amino-acid backbone with a fatty side chain that contains further amino-acid-like units, so FDA classified it as a drug.

Lilly challenged that decision in federal court in September 2024 (Eli Lilly and Co. v. Kennedy, S.D. Indiana). The court agreed with FDA that retatrutide is not a “protein” under the rule but set aside FDA’s finding that it is not “analogous to a protein” and returned that question to the agency. Lilly appealed to the Seventh Circuit (No. 26-1301, docketed 2026-02-17), which heard argument on 2026-09-24 and then asked both sides to brief whether it has jurisdiction over the appeal; those briefs were filed on 2026-10-08, and the docket showed no ruling when checked on 2026-10-26. The outcome matters for competition rather than for the review clock: a biological product licensed through a BLA can receive 12 years of exclusivity before a biosimilar can be approved (FDA guidance on reference product exclusivity), longer than the exclusivity a new drug receives. The PDUFA review goals are the same for an NME NDA and an original BLA.

Trials still running before and during review

Several phase 3 trials will report while the application is being prepared or reviewed. Dates are the primary completion dates registered by Lilly, which can move.

Trial	Question	Primary completion
TRANSCEND-T2D-2	vs semaglutide in type 2 diabetes (n=1,298 randomized)	2026-08-27; topline announced 2026-10-28 (see above), full paper not yet published
TRANSCEND-T2D-3	Type 2 diabetes with renal impairment (n=320)	2026-10
TRIUMPH-5	vs tirzepatide in obesity (n=800)	2026-11
TRIUMPH-7	Obesity with chronic low back pain (n=586)	2027-09
TRIUMPH-6	Keeping weight off (n=643)	2028-04
TRIUMPH-Outcomes	Heart and kidney events (n=10,000)	2029-02

For the trial-by-trial evidence, mechanism and study doses, see the retatrutide encyclopedia entry.

Side effects and open safety questions FDA will weigh

The trials report a side-effect profile broadly like other GLP-1-based medicines, with some signals of its own. In TRIUMPH-2, diarrhea affected 27–34% of people on retatrutide versus 13% on placebo and nausea 14–28% versus 8%; hypotension (up to 6% vs under 1%) and dysesthesia, an abnormal skin sensation (up to 7% vs 1%), were also more frequent [Human RCT, n=1,152] (Lancet 2026). Stopping treatment because of adverse events or death reached 12% on the middle dose versus 5% on placebo; investigators judged all deaths unrelated to the drug.

In TRIUMPH-4, Lilly reported dysesthesia in 20.9% at the highest dose versus 0.7% on placebo, and adverse-event discontinuation of 18.2% at that dose versus 4.0% on placebo [Human RCT, topline, n=445] (Lilly, 2025-12-11). The phase 2 obesity trial found dose-dependent increases in heart rate that peaked at 24 weeks and then declined [Human RCT, n=338] (Jastreboff et al., NEJM 2023). In TRANSCEND-T2D-2, adverse events led 4.8% (9 mg) and 7.9% (12 mg) to stop retatrutide versus 2.7% on Ozempic 2 mg; diarrhea (28–33% vs 26%) and nausea (21–24% vs 21%) were the most common side effects, and dysesthesia occurred in 4.8–6.5% versus 2.7% [Human RCT, topline, n=1,298] (Lilly, 2026-10-28). Long-term cardiovascular safety will not be settled until TRIUMPH-Outcomes reports.

Products sold before approval carry their own risk. FDA warns about retatrutide sold “for research purposes” or “not for human consumption” and says it cannot be compounded (FDA); the UK regulator reported seizing unlicensed retatrutide in its largest-ever raid on illegal weight-loss medicines on 2026-05-29 (MHRA). Such products have no verified identity, purity or sterility. In a case reported in October 2026, a woman in her mid-20s was admitted to hospital with persistent vomiting after four injections of an unverified product said to contain retatrutide, given by a wellness coach with no medical qualification (Buzzi 2026) [Human case report, n=1]. Our explainer on what the “research use only” label means covers the legal side.

Legal status until approval

Jurisdiction	Status	Source
US FDA	Investigational; BLA planned Q1 2027	Lilly
US compounding	Not permitted under federal law	FDA
US expanded access	Single-patient, physician-requested; BMI ≥35 with two or more serious complications	NCT07629401
UK	Unlicensed; seized by MHRA	MHRA
Sport (WADA)	Prohibited at all times, S0	WADA 2026

Expanded access is FDA’s pathway for a patient with a serious condition to receive an investigational product outside a trial when no comparable alternative exists and trial enrollment is not possible (FDA, Expanded access). Lilly’s program is limited to adults whose obesity has not responded to the highest available approved therapy and who cannot join a trial. For athletes, S0 applies to any substance with no current approval for human therapeutic use; see our page on peptides prohibited in sport.