Survodutide delivers up to 13.1% weight loss in Phase 3 SYNCHRONIZE-2; Zealand shares fall as much as 13%

Boehringer Ingelheim and Zealand Pharma reported full Phase 3 results on October 1, 2026 for survodutide, an experimental weekly injection that activates both the glucagon and GLP-1 receptors. In the SYNCHRONIZE-2 trial, adults with obesity or overweight plus type 2 diabetes lost up to 13.1% of their body weight after 76 weeks, compared with 3.1% on placebo ^[1]. The findings were presented at the 62nd Annual Meeting of the European Association for the Study of Diabetes in Milan and published simultaneously in the New England Journal of Medicine ^[1][2].

What the trial measured

SYNCHRONIZE-2 was a double-blind, placebo-controlled trial in 755 adults who received weekly injections of survodutide at 3.6 mg or 6.0 mg, or placebo, for 76 weeks ^[1][4]. The co-primary endpoints were percent change in body weight and the share of people losing at least 5% of their starting weight ^[4].

The headline 13.1% figure comes from what researchers call the efficacy estimand, which estimates the effect assuming people stayed on treatment for the whole study ^[1]. On that measure, 79.3% of people on survodutide lost at least 5% of their weight versus 32.7% on placebo, and HbA1c fell by up to 1.21% from a 7.4% baseline, against a 0.03% drop on placebo ^[1]. Waist circumference shrank 11.1 cm versus 3.5 cm ^[1], and up to 29.5% of treated participants returned to an HbA1c below 5.7% during treatment, compared with 4.0% on placebo ^[1].

The NEJM paper used a different lens, the treatment-regimen estimand, which counts results regardless of whether people stopped the drug, interrupted it, or added other weight-loss medicines ^[6]. By that measure, weight loss was 9.8% on the 6 mg dose and 8.2% on 3.6 mg, versus 3.9% on placebo ^[2][6]. Blood sugar results were also smaller under that approach, with reductions of 0.8% and 0.9% versus 0.2% on placebo ^[6].

Side effects were mostly gastrointestinal and mostly mild to moderate, including nausea, vomiting, diarrhea and constipation ^[1]. Discontinuation because of GI side effects was 18% on survodutide versus 1.2% on placebo ^[1][6]. Fierce Biotech reported broader figures from the trial: 26% of participants stopped after an adverse event and 39% had vomiting ^[2]. Boehringer said most dropouts happened during dose escalation, "as the study protocol allowed limited flexibility to manage adverse events," and that newer trials allow more flexible titration ^[1].

Why it matters for patients

Survodutide is not approved anywhere, and its efficacy and safety have not been established ^[1]. For now, it is a potential future option, not a current one.

The gap between 13.1% and 9.8% is a useful lesson in reading trial headlines. One number describes what happens if people stay on the drug; the other reflects real-world messiness, including people who stop because of side effects. Both are legitimate, and both come from the same trial.

The results also land in a crowded field. Investors reacted badly: Bloomberg reported Zealand shares fell as much as 13% in Copenhagen ^[3], while Fierce Biotech cited an 11% drop to 241 Danish kroner by midday ^[2] and BioSpace reported a decline of more than 8% ^[6]. BMO Capital Markets analysts had already called survodutide's profile "less competitive vs other agents" after the earlier SYNCHRONIZE-1 trial ^[2][6], where people without type 2 diabetes lost up to 16.6% versus 3.2% on placebo ^[6]. Weight loss is typically smaller in people with type 2 diabetes ^[2].

One area Boehringer continues to emphasize is fat distribution. In a SYNCHRONIZE-1 substudy of 75 people, MRI scans showed preferential loss of visceral and liver fat, with muscle accounting for no more than 10% of total tissue lost ^[1]. Earlier SYNCHRONIZE-1 data showed liver fat dropping up to 63.1% versus 25% in controls ^[2].

What happens next

Boehringer expects results from its cardiovascular outcomes trial, SYNCHRONIZE-CVOT, later this year ^[1]. The company has also launched a Phase 3 trial, SYNCHRONIZE-T2D, in adults with type 2 diabetes managed with diet and exercise or with medications including insulin ^[1]. Survodutide holds FDA Fast Track designation from May 2021 and Breakthrough Therapy designation from September 2024 for MASH with fibrosis ^[1]. No filing date for obesity has been disclosed.