Roche has reported Phase II clinical trial results for its experimental obesity drug CT-388, a once-weekly injectable dual GLP-1/GIP receptor agonist acquired through the company’s $2.7 billion purchase of Carmot Therapeutics in 2023. The mid-stage data showed placebo-adjusted weight loss of up to 22.5% after 48 weeks of treatment, supporting Roche’s plans to move the asset into late-stage testing.
According to the company, patients who fully adhered to the treatment regimen achieved placebo-adjusted weight loss of 22.5% at 48 weeks. When patients who did not strictly follow the treatment plan were included, the placebo-adjusted weight loss was 18.3%. Roche said treatment for a longer duration would likely yield improved outcomes, and the data did not show a weight loss plateau at the 48-week mark.
More than 95% of patients receiving CT-388 achieved weight loss of more than 5% at week 48, while more than a quarter of participants lost 30% or more of their body weight. In addition, more than half of treated participants achieved resolution of obesity, compared with 13% of patients in the placebo group.
The study also examined outcomes among patients with pre-diabetes at enrollment. Roche reported that 73% of these patients receiving CT-388 had normal blood glucose levels at week 48, compared with 7.5% in the placebo arm.
Roche said the treatment was well tolerated, with mild to moderate gastrointestinal side effects consistent with other incretin-based medicines. The discontinuation rate was 5.9% among patients receiving CT-388, compared with 1.3% in the placebo group. Roche did not provide detailed reasons for discontinuations but said additional data would be presented at an upcoming medical meeting.
Roche said the Phase II results help build the case for advancing CT-388 into late-stage testing, which is scheduled to begin this quarter. The company said the results were based on the highest of five doses tested and validated decisions made in late 2025 to design two larger Phase III trials.
CT-388 was one of several obesity-related assets acquired in the Carmot Therapeutics transaction. Roche has since moved to accelerate development of these molecules, with CT-388 flagged for fast-track development within the company’s pipeline.
The drug is also being studied in combination with petrelintide, an amylin analog developed by Zealand Pharma that works through a different mechanism than GLP-1 therapies. Roche and Zealand are expected to initiate a combination study in the first half of this year. The aim of the combination is to provide a weight loss treatment without the gastrointestinal side effects commonly associated with GLP-1 medicines.
Commenting on the trial results, Manu Chakravarthy, Roche’s head of development for cardiovascular, renal, and metabolic diseases, said: “To see no plateau and this very steep linear trajectory is likely a reflection of this potential for higher efficacy.”
Roche said CT-388 is expected to launch in 2029. The company currently has six drug candidates in clinical trials for obesity and related conditions, including type 2 diabetes and hypertension, and forecasts that three of them could achieve annual sales of more than $1 billion.
Roche Shares Phase II Trial Results
New Phase II clinical trial results for the investigational obesity drug CT-388 demonstrated substantial and sustained weight loss among participants, with some patients achieving up to 22.5% average weight reduction. The findings highlight the drug’s strong efficacy profile and its potential role in addressing the growing global obesity burden.
The study showed consistent performance across multiple dosing groups, with participants experiencing steady weight loss throughout the trial period. These results suggest that the therapy may offer durable benefits when used over time, an important factor for long-term obesity management.
In addition to weight reduction, trial data indicated improvements in key metabolic health markers, including insulin sensitivity and lipid levels. Such changes are considered important for reducing the risk of obesity-related complications such as cardiovascular disease and type 2 diabetes.
