Boehringer reports up to 16.6% weight loss with survodutide in Phase 3 trial

Boehringer Ingelheim reported on April 28, 2026 that survodutide, an experimental glucagon/GLP-1 dual agonist, helped adults with obesity or overweight lose an average of up to 16.6% of their body weight after 76 weeks of treatment ^[1]. The Phase 3 SYNCHRONIZE-1 trial enrolled 725 adults without type 2 diabetes who received weekly injections of survodutide at 3.6 mg or 6.0 mg, or a placebo ^[1][2].

That 16.6% figure uses the efficacy estimand, which estimates the treatment effect if participants stayed on the drug for the entire study; placebo participants lost 3.2% on the same measure (p<0.0001) ^[1]. Under the treatment-regimen estimand, which counts people who stopped treatment or started other therapies, weight loss was 12.2% at 3.6 mg and 13.0% at 6.0 mg versus 5.4% with placebo ^[2]. Boehringer said average weight loss reached up to 39.2 pounds (17.8 kilograms) from baseline ^[1].

On the second main endpoint, the company said up to 85.1% of survodutide-treated participants lost at least 5% of body weight on the efficacy estimand, versus 38.8% on placebo ^[1]. A report on the same trial gives lower percentages for that measure — 72.6% and 71.9% for the two doses versus 46.3% for placebo — and says 28.5% of those on 6.0 mg lost at least 20% of body weight versus 6.6% on placebo ^[2].

Boehringer said the weight loss came mainly from fat tissue, with lean mass contributing only a small share ^[1]. In a prespecified MRI substudy of about 25 participants per arm, liver fat fell 63.1% at the 6.0 mg dose versus 24.5% with placebo, and visceral fat fell 34.0% versus 11.8%, while lean body volume declined 9.8% ^[2]. The company also reported a statistically significant reduction in waist circumference, a marker tied to visceral fat and cardiometabolic risk, but did not release those numbers at topline ^[1][4].

The main open question is tolerability. Boehringer said gastrointestinal events occurred as expected with GLP-1 based therapies, were mild to moderate and temporary, and led to discontinuations more often during dose escalation, but it did not provide figures ^[1][4]. A report on the trial states GI side effects caused 17.8% of the 3.6 mg group and 20.2% of the 6.0 mg group to stop treatment, versus 2.9% on placebo ^[2]. No deaths were reported, and there were no confirmed cases of pancreatic cancer, thyroid cancer or acute pancreatitis; heart rate rose 3.2 to 3.5 beats per minute ^[2].

One limitation: the placebo group lost more weight than the trial was designed to expect — 5.4% instead of the 2% to 3% assumed — which investigators attributed partly to more than 16% of placebo participants reporting use of a prohibited GLP-1 medication while still enrolled ^[2].

Why it matters for patients

Survodutide would join a market that already includes semaglutide (Ozempic, Wegovy, Rybelsus) and tirzepatide (Mounjaro, Zepbound). Its placebo-adjusted weight loss of 13.4% is in the same range as figures reported for existing drugs in similar populations — 12.4% for Wegovy at 68 weeks and 17.8% for Zepbound at 72 weeks ^[4].

What may set it apart is where the fat comes off. Liver fat and visceral fat fell by more than weight alone would predict, which could matter for people with fatty liver disease or high cardiometabolic risk, though those results come from a small imaging substudy ^[1][2]. That dose-fat pattern appears earlier than weight loss alone would explain, according to Lee Kaplan, MD, PhD, director of the Obesity and Metabolism Institute at Massachusetts General Hospital, who said the effect "is specific to the treatment and is specific to the liver more than it is just an association with the amount of weight loss" ^[2].

Stopping treatment is the practical trade-off. About one in five people at the higher dose discontinued because of GI side effects in one account ^[2], and 24.6% discontinued in the Phase 2 trial ^[4]. In clinical discussion of the data, women lost more weight than men (about 19.5% versus 12.6% at 6.0 mg), a pattern also seen with other GLP-1 drugs ^[2].

What happens next

Full SYNCHRONIZE-1 data will be presented at the American Diabetes Association 2026 Scientific Sessions in June, and the obesity results were published in the New England Journal of Medicine ^[1][2]. Boehringer said more results from its Phase 3 obesity program are expected during 2026 ^[1].

Separately, the LIVERAGE and LIVERAGE-Cirrhosis Phase 3 trials are testing survodutide in adults with MASH and fibrosis ^[1]. Survodutide holds FDA Fast Track designation from May 2021 and Breakthrough Therapy designation from September 2024 for non-cirrhotic MASH with moderate or advanced fibrosis ^[1]. A timeline for regulatory filing has not been reported.