GLP-1 CollectivePolicy Tracker · Patient Lens · October 4, 2026
Two trials test switching from one weight-loss drug to another
Boehringer Ingelheim will enroll 350 adults without diabetes, some new to GLP-1 drugs and some switching from one, while Novo Nordisk checks if switching to its newer drug is safe.
Key details
- A Novo Nordisk phase 1 trial starting fall 2026 will test whether switching from semaglutide to zenagamtide is safe for 60 people.
- Boehringer Ingelheim will enroll 350 people without diabetes starting November 2026 to test survodutide, a new weight-loss injection, in people new to GLP-1 drugs and people switching from one.
Two new trials, tracked on October 3, 2026, look at what comes after semaglutide. One asks whether people already on the drug can switch to something newer without problems. The other tests a different injection in people new to GLP-1 drugs and in people switching from one. If you take semaglutide now or are considering a GLP-1 for weight loss, both studies could shape what options you have later.
Novo Nordisk's phase 1 trial, set to begin in fall 2026, will enroll 60 adults with overweight or obesity, with or without type 2 diabetes, who are currently taking semaglutide. The study asks a narrow but practical question: can these patients move to zenagamtide, a newer GLP-1 drug, safely? This matters because many people on semaglutide eventually look for an alternative, and right now there is little formal data on what switching does to tolerability or side effects. A phase 1 study of this size will not settle the question on its own. It should offer early signals on whether a planned transition between these two drugs is reasonable to study further in larger trials.
Boehringer Ingelheim's trial, called SYNCHRONIZE-START, takes a different approach. Starting in November 2026, the company will enroll 350 people with overweight or obesity who do not have diabetes, some new to GLP-1 drugs and some switching from one. This is a phase 3 study, meaning survodutide has already moved past early safety testing and is now being evaluated at a scale closer to what the FDA would need for approval. Because the trial has two groups, one starting survodutide as a first treatment and one switching to it from another GLP-1 drug, it should show how the drug performs both ways.
These two trials are tracking different questions, and the answers will not arrive at the same time or in the same way. If you are on semaglutide and wondering about switching, the Novo trial is the one to watch, though phase 1 data takes time to mature. The Boehringer trial may eventually tell you more about survodutide, whether you are new to GLP-1 drugs or thinking about switching. In either case, I would suggest waiting for published results before changing your treatment plan, and talking with your prescriber about what these trials could mean for you.
By Amanda Bonello