Retatrutide vs Survodutide: Comparing MASLD Liver-Fat Trial Data
TL;DR: Survodutide's Phase 3 MASLD liver-fat trial (Nature Medicine, 8 Jun 2026) just published; retatrutide's own liver data is still Phase 2a.
What New MASLD Liver-Fat Data Did Survodutide Just Publish?
On 8 June 2026, Nature Medicine published the full results of SYNCHRONIZE-MASLD, a Phase 3 trial of survodutide (BI 456906), Boehringer Ingelheim and Zealand Pharma's glucagon receptor/GLP-1 receptor dual agonist, in adults with obesity and metabolic dysfunction-associated steatotic liver disease (MASLD).[1] The trial had been presented in topline form at the American Diabetes Association's 2026 Scientific Sessions in New Orleans earlier the same month.[2]
The result is notable in the incretin research field beyond survodutide itself: it is one of the first completed Phase 3, peer-reviewed liver-fat datasets in this drug class, arriving before Eli Lilly has published an equivalent late-stage hepatic trial for retatrutide, whose own liver-fat evidence to date remains at the earlier Phase 2a stage.
What Did the SYNCHRONIZE-MASLD Trial Find?
Design: 216 adults with obesity and at-risk MASLD (liver inflammation and/or fibrosis on non-invasive testing, or biopsy-confirmed MASH) were randomised 2:1 to once-weekly subcutaneous survodutide 6.0mg (n=146) or placebo (n=70) for 48 weeks. Co-primary endpoint: 84.2% of participants on survodutide achieved a 30% or greater relative reduction in MRI-PDFF-assessed liver fat content, versus 24.3% on placebo. Companion signal: a separately reported general-obesity Phase 3 trial in the same SYNCHRONIZE programme, SYNCHRONIZE-1, showed sustained weight loss of up to 16.6% at 76 weeks, with up to 34% visceral-fat and 63% liver-fat reduction in pre-specified body-composition analyses.[3]
Source: PubMed ID 42252333; Boehringer Ingelheim / Zealand Pharma press materials, June 2026
Both SYNCHRONIZE trials sit alongside Boehringer and Zealand's earlier Phase 2 work on survodutide in MASH and fibrosis, published in the New England Journal of Medicine in 2024, which first established the liver-fat signal that the Phase 3 programme was designed to confirm at scale.[4]
What Liver-Fat Evidence Exists for Retatrutide?
Design: 98 adults with MASLD were randomised to once-weekly retatrutide 1mg (n=20), 4mg (n=19), 8mg (n=22), 12mg (n=18), or placebo (n=19) for 48 weeks. Result at 48 weeks: mean relative liver-fat reductions of 81.7% (8mg) and 86.0% (12mg), versus a 4.6% increase on placebo. Steatosis resolution (liver fat below 5%) was reached by 89% (8mg) and 93% (12mg) of participants, versus 0% on placebo.[5]
Source: PMC11271400; Nature Medicine, 2024
This remains the primary published liver-fat dataset for retatrutide. Eli Lilly has referenced hepatic outcomes as part of its ongoing Phase 3 TRIUMPH programme, and our own coverage of TRIUMPH-4 notes that MASLD is listed among indications for further trial readouts expected through 2026–2027, but as of this writing Lilly has not published a completed, dedicated Phase 3 hepatic-outcomes trial equivalent to SYNCHRONIZE-MASLD.[6]
How Do the Two Datasets Compare Side by Side?
| Compound | Trial (phase) | n | Duration | Reported liver-fat result |
|---|---|---|---|---|
| Retatrutide 12mg | MASLD study (Phase 2a) | 98 total | 48 wks | −86.0% mean reduction; 93% resolution |
| Retatrutide 8mg | MASLD study (Phase 2a) | 98 total | 48 wks | −81.7% mean reduction; 89% resolution |
| Survodutide 6.0mg | SYNCHRONIZE-MASLD (Phase 3) | 216 total | 48 wks | 84.2% reached ≥30% reduction (vs 24.3% placebo) |
Figures are as reported in each publication for different trial phases, endpoints and sample sizes. This table is for contextual research reference only and is not a head-to-head clinical comparison.
The two trials do not measure quite the same thing. Retatrutide's Phase 2a study reports a mean percentage reduction in liver fat across dosed participants, plus a separate steatosis-resolution rate. Survodutide's Phase 3 trial reports the proportion of participants crossing a pre-specified 30% relative-reduction threshold. Both are legitimate ways to summarise MRI-PDFF liver-fat data, but the differing metrics, populations and trial sizes mean the headline numbers cannot be read as a direct efficacy ranking.
Why Does Trial Phase Matter More Than the Headline Number?
Phase 3 carries more regulatory weight
SYNCHRONIZE-MASLD's larger, longer, purpose-designed Phase 3 structure is the kind of evidence regulators expect to see before a MASLD/MASH indication filing — a bar retatrutide's smaller Phase 2a MASLD study was never designed to clear on its own.
A competitor may reach the finish line first
If Lilly has not yet completed a dedicated Phase 3 hepatic-outcomes trial for retatrutide, Boehringer and Zealand's published Phase 3 liver dataset means survodutide could plausibly reach a MASLD-specific regulatory submission first, independent of retatrutide's own numerically larger Phase 2a signal.
Validates the underlying receptor biology
Both compounds pair a GLP-1 receptor mechanism with a second receptor associated with hepatic fatty-acid oxidation (glucagon for both, plus GIP for retatrutide) — two independent trial programmes reaching large liver-fat reductions strengthens confidence in that shared mechanistic rationale.
What Should UK Researchers Take From This?
Survodutide is an unapproved, patent-protected investigational drug confined to Boehringer Ingelheim and Zealand Pharma's registered trials. It is not available for purchase, compounding, or research use from any lawful source, and Velox Peptides does not supply it. Its published Phase 3 liver-fat result is evidence that the glucagon-receptor mechanism retatrutide research also addresses continues to attract independent confirmation from a second well-funded pipeline.
That does not change retatrutide's own regulatory position. It remains an unlicensed investigational medicine, with a Phase 3 NDA filing targeted for Q4 2026 in the US on its obesity indication and no confirmed MHRA timeline or completed Phase 3 MASLD dataset. Velox Peptides supplies retatrutide strictly as an HPLC-verified in vitro research reagent, with batch-specific certificates of analysis, and makes no therapeutic or liver-health claims for it.
Retatrutide is supplied as a research reagent only. It is not a medicine and has not been evaluated by the MHRA or FDA for use in our products. Not for human or veterinary use. Survodutide is not a Velox Peptides product and is not available for sale. See our Research Use Policy and MHRA Statement.
References
- Survodutide in Adults with Obesity and Metabolic Dysfunction-Associated Steatotic Liver Disease: SYNCHRONIZE-MASLD, a Randomized, Double-Blind, Placebo-Controlled Phase 3 Trial. Nature Medicine, 8 June 2026. PMID: 42252333. pubmed.ncbi.nlm.nih.gov
- Boehringer Ingelheim. Positive data from two Phase III SYNCHRONIZE obesity trials. ADA 2026 Scientific Sessions, June 2026. boehringer-ingelheim.com
- Zealand Pharma. Zealand Pharma announces Boehringer Ingelheim's survodutide Phase III trial in people living with obesity showed targeted 34% visceral and 63% liver fat reduction. 7 June 2026. globenewswire.com
- A Phase 2 Randomized Trial of Survodutide in MASH and Fibrosis. New England Journal of Medicine, 2024. nejm.org
- Sanyal AJ, et al. Triple Hormone Receptor Agonist Retatrutide for Metabolic Dysfunction-Associated Steatotic Liver Disease: A Randomized Phase 2a Trial. Nature Medicine, 2024. PMC11271400. pmc.ncbi.nlm.nih.gov
- Eli Lilly and Company. Lilly's triple agonist, retatrutide, delivered weight loss of up to an average of 71.2 lbs along with substantial relief from osteoarthritis pain in first successful Phase 3 trial. December 2025 / ADA 2026 update, 6 June 2026. investor.lilly.com
Frequently Asked Questions
What did survodutide's SYNCHRONIZE-MASLD trial show?
SYNCHRONIZE-MASLD, a Phase 3 trial of 216 adults with obesity and metabolic dysfunction-associated steatotic liver disease (MASLD), reported that 84.2% of participants on once-weekly survodutide 6.0mg achieved a 30% or greater relative reduction in MRI-PDFF-assessed liver fat at 48 weeks, versus 24.3% on placebo. Full results were published in Nature Medicine on 8 June 2026 and presented at the ADA 2026 Scientific Sessions.
What liver-fat data exists for retatrutide?
Retatrutide's liver-fat evidence comes from a smaller, earlier-phase trial: a Phase 2a study (Sanyal et al., Nature Medicine, 2024; n=98) reported mean relative liver-fat reductions of 81.7% (8mg) and 86.0% (12mg) at 48 weeks versus a 4.6% increase on placebo, with steatosis resolution (liver fat below 5%) in 89% and 93% of participants respectively. Eli Lilly has not yet published an equivalent Phase 3 hepatic-outcomes trial for retatrutide.
Can retatrutide's and survodutide's liver-fat results be compared head-to-head?
Not directly. The trials used different endpoints (mean percentage reduction and steatosis resolution for retatrutide vs. proportion reaching a 30% relative-reduction threshold for survodutide), different trial phases, different populations, and different sample sizes. Retatrutide's numerically larger mean reduction comes from a smaller Phase 2a study; survodutide's result is from a larger, regulatory-grade Phase 3 trial. Neither figure should be read as superiority evidence.
Why does trial phase matter here?
Phase 3 trials are larger, longer, and specifically designed to support regulatory submissions, so survodutide's SYNCHRONIZE-MASLD result carries more regulatory weight than retatrutide's Phase 2a signal, even though retatrutide's numbers are directionally larger. It means a competitor may reach a completed, published Phase 3 MASLD dataset before Lilly does for retatrutide, despite retatrutide's early data looking strong.
Is retatrutide available as a research reagent for MASLD-related studies?
Velox Peptides supplies retatrutide strictly as an HPLC-verified in vitro research reagent for qualified laboratory research. It is not licensed for any indication, including MASLD, is not a medicine under the Human Medicines Regulations 2012, and Velox Peptides makes no therapeutic or liver-health claims for it. Survodutide is not a Velox Peptides product.