SYNCHRONIZE-1 was a phase 3 double-blind trial that randomised 725 adults with obesity, defined as a body mass index of 30 or higher, or 27 or higher with a weight-related complication, to once-weekly subcutaneous survodutide titrated up to 3.6 mg, up to 6.0 mg, or placebo, all with lifestyle counselling. Diabetes was an exclusion. Mean age was 47, mean body mass index 37.9 and mean weight 108.8 kg. The primary analysis used a treatment-regimen estimand, which keeps people who stopped early in their original group.
At 76 weeks, weight fell 12.2% (95% CI -13.6 to -10.8) on 3.6 mg and 13.0% (-14.4 to -11.6) on 6.0 mg, against 5.4% (-6.9 to -4.0) on placebo. Some 72.6% and 71.9% lost at least 5% of body weight, against 46.3% on placebo. The two doses barely separated. Gastrointestinal symptoms, mostly mild to moderate, affected 80.9% and 89.7% of the two drug groups against 47.9% on placebo.
This is the second glucagon and GLP-1 dual agonist to report in a week, after mazdutide on Friday. The glucagon arm of these molecules is meant to add energy expenditure and liver fat loss on top of the appetite suppression GLP-1 provides. On these numbers survodutide's weight loss sits below what tirzepatide and high-dose semaglutide achieve, and the flat response above 3.6 mg suggests tolerability, not receptor coverage, is what limits the dose.
Nothing follows for clinic today: survodutide is investigational and approved nowhere. When patients ask about the next injection, the honest answer is that more molecules are coming and none has yet beaten the best current option on weight. The placebo group losing 5.4% is also worth holding on to, because it is what structured lifestyle counselling achieved on its own.
- Survodutide is investigational; no prescribing decision follows from this trial.
- The 3.6 mg and 6.0 mg doses gave almost identical weight loss, so going higher bought side effects rather than efficacy.
- Gastrointestinal symptoms affected 8 or 9 in 10 participants; ask patients on any incretin what mild nausea is actually costing them.
- Diabetes was an exclusion criterion, so this trial says nothing about glycaemic effect.
- Placebo plus counselling gave 5.4% weight loss; keep structured lifestyle support in the plan whatever the drug.
The statistics, in plain English
The confidence intervals for 3.6 mg (-13.6 to -10.8) and 6.0 mg (-14.4 to -11.6) overlap almost completely, which is the statistical way of saying the higher dose did not do more. The treatment-regimen estimand counts everyone in the group they were assigned to, including those who stopped the drug, so it answers the question a clinician actually has, what happens if I start this, and gives a smaller number than an estimand counting only people still taking it. Subtracting the 5.4% placebo change leaves roughly 7 to 8 percentage points attributable to the drug itself. The proportion reaching 5% loss, 72.6% against 46.3%, matters more than the mean for counselling, because it describes how many individuals responded rather than what happened on average.
Read the rest in the app
You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.
Scan to keep reading on your phone. No account needed to start.
Tomorrow morning, before your first patient
One edition a day for diabetes & endocrinology, written by the desk, every claim tied to its paper. Six minutes.
Get the app — free