Roche said the Phase II results help build the case for advancing CT-388 into late-stage testing, which is set to get underway this quarter.
Roche’s dual GLP-1/GIP receptor agonist candidate achieved 22.5% weight loss after nearly a year of treatment, setting the asset up for late-stage testing and a potential challenge to Eli Lilly’s mega-blockbuster obesity franchise.
While the data is limited, William Blair’s analysts saw enough to declare that Roche’s CT-388 appears comparable to Lilly’s Zepbound, according to a Tuesday morning note.
The hotly anticipated results come from a Phase II trial of CT-388, an asset picked up in 2023 through the $2.7 billion acquisition of Carmot Therapeutics. Once-weekly injections of CT-388 led to placebo-adjusted weight loss of 22.5% at 48 weeks, without a weight loss plateau, according to Roche’s Tuesday announcement. More than 95% of patients achieved weight loss of more than 5% at 48 weeks, with more than a quarter achieving weight loss of 30%.
More than half of participants achieved resolution of obesity, compared to 13% in the placebo group.
The company also reported that 73% of patients who entered the trial with pre-diabetes saw normal blood glucose levels at week 48, compared to just 7.5% in the placebo group.
Roche said the treatment was well-tolerated, with mild to moderate gastrointestinal side effects consistent with other incretin medicines. The study also saw a discontinuation rate of 5.9% in the treatment arm and 1.3% in the placebo group. Roche did not provide specifics of the dropouts but promised to release more data at an upcoming medical meeting.
Roche in its statement said these Phase II results will help build the case for advancing CT-388 into late-stage testing, which is set to get underway this quarter.
After buying CT-388 and a batch of other obesity assets in the Carmot transaction, Roche has moved quickly to accelerate the development of those new molecules. CT-388 in particular has been flagged for the fast-track in the pharma’s pipeline. The therapy is also being combined with petrelintide, Zealand Pharma’s amylin analog that provides a different mechanism of action for weight loss from the already-approved GLP-1 class of medications. The aim is to offer a weight loss solution without the gastrointestinal side effects that have become well-known among patients taking GLP-1s.
Roche and partner Zealand are expected to initiate a combo study of the medicines in the first half of this year.
CT-388 is expected to lead a new wave of obesity molecules that provide steeper weight loss than incumbents Wegovy, from Novo Nordisk, and Zepbound, from Lilly, Morningstar Equity Research wrote in a November 2025 report. The asset is not expected to launch until 2029, however, according to Morningstar.
William Blair noted that Zepbound achieved about another 2% weight loss from week 48—the cut-off for Roche’s data—and week 72. So CT-388’s effect could grow in future readouts for the Phase II trial.
Lilly is also leading this charge with retatrutide, a triple hormone receptor agonist that cut body weight by 26.6% on a placebo-adjusted basis at 68 weeks. Analysts have said the asset could have promise in treating patients with more severe obesity, an indication that may garner easier uptake from insurers and other payers that have been reluctant to provide broader coverage of the disease.
CT-388 is also about a year behind a similar asset from Viking Therapeutics called VK2735, according to William Blair.
