Roche has reported that its dual GLP-1/GIP receptor agonist candidate, CT-388, resulted in a 22.5% weight loss after nearly one year of treatment in a Phase II clinical trial. The results position CT-388 for late-stage testing and may allow Roche to compete with Eli Lilly’s established obesity drug franchise.
According to analysts from William Blair, the available data suggests that CT-388 is comparable to Eli Lilly’s Zepbound. The findings were released following Roche’s announcement on Tuesday.
The Phase II study involved once-weekly injections of CT-388, which led to a placebo-adjusted weight loss of 22.5% at 48 weeks without reaching a plateau. Over 95% of participants experienced more than 5% weight loss, and more than 25% lost at least 30% of their body weight. More than half of the participants achieved resolution of obesity compared to 13% in the placebo group.
Additionally, Roche reported that among patients who started the trial with pre-diabetes, 73% had normal blood glucose levels at week 48 versus only 7.5% in the placebo group.
The company stated that "the treatment was well-tolerated, with mild to moderate gastrointestinal side effects consistent with other incretin medicines." The discontinuation rate was 5.9% in the treatment arm and 1.3% in the placebo group. While specific details about dropouts were not provided, Roche said it would release more information at an upcoming medical meeting.
Roche said these Phase II results will support advancing CT-388 into late-stage trials, which are scheduled to begin this quarter.
Following its acquisition of Carmot Therapeutics and its portfolio for $2.7 billion in 2023, Roche has expedited development efforts for these new obesity drugs. CT-388 has been prioritized within Roche's pipeline and is also being tested in combination with petrelintide, an amylin analog from Zealand Pharma that uses a different mechanism for weight loss compared to existing GLP-1 drugs. This combination aims to provide effective weight loss while minimizing gastrointestinal side effects commonly associated with GLP-1 treatments.
Roche and Zealand plan to start a combination study of these medications within the first half of this year.
Morningstar Equity Research indicated that CT-388 could lead a new generation of obesity treatments offering greater weight loss than current options such as Novo Nordisk’s Wegovy and Eli Lilly’s Zepbound; however, Morningstar does not expect CT-388 to be launched before 2029.
William Blair noted that Zepbound produced about an additional two percent weight loss between weeks 48 and 72—beyond the time frame covered by Roche's data—suggesting CT-388’s efficacy could increase over longer periods as further results become available from ongoing studies.
Eli Lilly is also advancing retatrutide, a triple hormone receptor agonist that reduced body weight by 26.6% on a placebo-adjusted basis at week 68 in trials. Analysts believe retatrutide may be especially useful for patients with severe obesity—a segment where insurers might be more willing to offer coverage.
CT-388 trails Viking Therapeutics’ similar asset VK2735 by approximately one year according to William Blair.
