Roche’s dual GLP-1/GIP receptor agonist has been tied to 22.5% weight loss at 48 weeks, validating the company’s decision to move the asset into phase 3 studies this quarter.
The Swiss Big Pharma evaluated three subcutaneous doses of the drug, dubbed CT-388, against placebo in a phase 2 study of 469 people with obesity or who were overweight. The primary endpoint was percent change in placebo-adjusted body weight from baseline to Week 48, with the highest, 24-mg, dose seeing 22.5% weight loss by this point.
On a first look, the readout suggests CT-388 is in the same ballpark as Eli Lilly’s blockbuster GLP-1/GIP agonist Zepbound, for which a 15-mg dose was tied to a (PDF) 20.9% reduction in body weight after 36 weeks.
Roche said that when it came to the treatment-regimen estimand, the placebo-adjusted weight loss achieved with CT-388 was 18.3%. The company didn’t detect weight loss plateauing by the 48-week mark, the company explained in a Jan. 27 release.
A total of 95.7% of patients who received the highest dose achieved weight loss of more than 5%, while 26.1% achieved weight loss of more than 30%, the company noted.
While Roche is holding back the full data for a future medical conference, the company did describe CT-388 as well tolerated, with the “majority of gastrointestinal-related adverse events being mild-to-moderate, generally consistent with the incretin class of medicines.”
A total of 5.9% patients who received CT-388 discontinued treatment compared to 1.3% in the placebo cohort.
“We are pleased to see such meaningful weight loss in people treated with CT-388,” Roche Chief Medical Officer Levi Garraway, M.D., Ph.D., said in a statement. “The robust weight loss combined with a well-tolerated safety profile reinforces our confidence in the clinical development programme as we advance to phase 3 trials.”
The plan is now to take CT-388 into a pair of phase 3 obesity studies this quarter, Roche confirmed today. The company first outlined its phase 3 ambitions for the asset at Roche’s Pharma Day back in September 2025. At that event, the company unveiled a strategy to become a “top three” obesity company, in part by combining assets across Roche’s wider portfolio.
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One of these potential combinations will be allying CT-388 with petrelintide to address nausea, which is the main driver of discontinuation from existing weight loss products. Roche penned a $1.6 billion upfront deal with Zealand Pharma last year to codevelop and co-commercialize petrelintide, a long-acting amylin analog.
CT-388’s origins also lie outside the company, with Roche having acquired the GLP-1/GIP as part of its $2.7 billion buyout of Carmot Therapeutics back in 2023. Earlier this month, Roche also paid $100 million to Structure Therapeutics for a nonexclusive license to certain patents related to CT-996, an oral GLP-1 drug that also came over from the Carmot acquisition.
Roche has been deliberately keeping its options open in the obesity space. In September, the pharma’s global head of cardiovascular, renal and metabolism product development Manu Chakravarthy, M.D., Ph.D., told Fierce that he rejects the idea that “you need to have this one megablockbuster that will make you [an obesity leader].”
“In fact, I would submit that if you only had that, you would be severely handicapped in addressing the complexity and the heterogeneity of what we know the obesity market is,” he said at the time.
Analysts at ODDO BHF welcomed the readout, which they said represented a “material pipeline upgrade for Roche.”
“We have had very limited data on its obesity pipeline ambition in the past,” the analysts noted. “These first data are seen as positive, justifying the investments in the franchise.”
“The combination of depth of response, absence of an early plateau and acceptable tolerability suggests CT-388 could sit in the top efficacy tier if replicated in phase 3,” they added in a Jan. 27 note.