Survodutide Phase 3 data published in NEJM show 34% visceral and 63% liver fat reduction

Boehringer Ingelheim released full Phase 3 results on June 7, 2026, for survodutide, an experimental once-weekly injection that activates both the glucagon and GLP-1 receptors. The data from two trials — SYNCHRONIZE-1 and SYNCHRONIZE-MASLD — were presented at the American Diabetes Association's 2026 Scientific Sessions and published simultaneously in The New England Journal of Medicine and Nature Medicine ^[1][2].

The headline from a prespecified imaging substudy: at the 6.0 mg dose, participants lost 63.1% of their liver fat and 34.0% of their visceral fat (the fat packed around abdominal organs) over 76 weeks, compared with 24.5% and 11.8% in the placebo group ^[2]. Lean body volume fell 9.8%, meaning more than 89% of the total tissue change was fat rather than muscle ^[2]. Boehringer described the same finding slightly differently, saying lean mass accounted for "no more than 11.3%" of the change in total tissue mass at the highest dose ^[1]. The substudy was small — about 25 participants per arm ^[2].

What the weight numbers show

SYNCHRONIZE-1 enrolled 725 adults with a BMI of 30 or higher, or 27 or higher with at least one weight-related complication, and excluded people with type 2 diabetes ^[2]. Participants were randomized to survodutide 3.6 mg (n=241), 6.0 mg (n=242) or placebo (n=242) across 116 sites in 14 countries between November 2023 and February 2026 ^[2].

At week 76, average weight change under the treatment-regimen estimand — which counts people who stopped treatment — was −12.2% and −13.0% versus −5.4% for placebo ^[2]. Under the efficacy estimand, which models full adherence, the figures were −15.3% and −16.6% versus −3.2% ^[1][2]. About 28.5% of the 6.0 mg group lost at least 20% of body weight, versus 6.6% on placebo ^[2].

An unusual wrinkle: the placebo group lost far more weight than the 2% to 3% investigators had planned for. More than 16% of placebo participants reported using a prohibited GLP-1 medication while still enrolled ^[2]. Lead investigator Carel le Roux, MBChB, PhD, said, "We are getting into a space now where it's becoming harder and harder for us to run drug against placebo" ^[2].

The liver trial

SYNCHRONIZE-MASLD enrolled 218 adults with overweight or obesity and metabolic dysfunction-associated steatotic liver disease with evidence of inflammation and/or fibrosis, with and without type 2 diabetes ^[1][2]. Average age was 55, average BMI 39.6, and 38.4% had type 2 diabetes; baseline liver fat averaged 16.9% by MRI ^[2].

After 48 weeks on 6.0 mg, up to 84.2% of treated participants achieved at least a 30% relative reduction in liver fat versus 24.3% on placebo, and 61.0% reached liver fat normalization (under 5%) versus 5.7% ^[1][2]. Weight fell up to 12.2% versus 1.0% ^[1].

Side effects

Gastrointestinal side effects — nausea, vomiting, diarrhea, constipation — were the most common and clustered during dose escalation ^[1]. Discontinuations from GI events were 17.8% at 3.6 mg and 20.2% at 6.0 mg versus 2.9% on placebo ^[2]; Boehringer's release cited 19% overall for survodutide ^[1]. Overall premature discontinuation ran 35% to 40%, which discussant Jaime Almandoz, MD, said points to a need for individualized titration and behavioral support ^[2]. No deaths occurred, no confirmed major cardiovascular events happened in the survodutide arms, and there were no confirmed cases of pancreatitis, pancreatic cancer or thyroid cancer ^[2]. Heart rate rose 3.2 to 3.5 beats per minute ^[2].

Why it matters for patients

Survodutide is not approved anywhere and its safety and efficacy have not been established ^[1]. Nothing here changes what is available at a pharmacy today.

What the data add is a different question than "how many pounds." Up to 75% of people with obesity develop MASLD, and about one in three of those can progress to MASH, which involves inflammation and liver damage ^[1]. The trials suggest the glucagon half of the molecule may act directly on the liver, with liver fat dropping earlier and more steeply than weight loss alone would predict ^[2]. If that holds up in larger studies, it could shape how insurers and doctors judge these drugs.

The tolerability picture is also relevant. Roughly one in five participants stopped because of stomach side effects ^[2] — higher than the weight-loss numbers alone would suggest.

What happens next

Boehringer says three Phase IIIb trials start later in 2026: SYNCHRONIZE-HERA in women's health, ELEVATE-LIVER on cardiac function in MASLD/early MASH, and SYNCHRONIZE-START on real-world titration and switching from GLP-1 drugs ^[1]. Two MASH trials, LIVERAGE and LIVERAGE-Cirrhosis, are ongoing ^[1]. Survodutide holds FDA Fast Track (May 2021) and Breakthrough Therapy (September 2024) designations for MASH with fibrosis ^[1]. No FDA submission date has been announced in these sources.