Roche AG has reported strong results from a mid-stage clinical trial of its experimental weight loss drug, CT-388, showing that study subjects lost an average of 22.5% of their body weight after 48 weeks of observation. Based on these findings, the company plans to move the drug into large Phase 3 trials later this year.
The highest dose produced the greatest weight loss. Nearly 96% of participants on this dose lost at least 5% of their body weight, and about 26% lost more than 30%. Importantly, researchers did not observe weight loss slowing by the end of the 48-week study, suggesting patients could continue to benefit from the medication over an extended period of time.
The results place CT-388 in a similar effectiveness range to leading GLP-1 weight loss drugs already on the market, including Zepbound from Eli Lilly. Roche also reported that the drug was generally well tolerated; most side effects were mild to moderate digestive issues, which are common with this class of medications. Fewer than 6% of patients stopped treatment due to side effects, compared to just over 1% in the placebo group.
Roche plans to begin two Phase 3 obesity studies soon and is exploring ways to improve tolerability further by combining CT-388 with other treatments. The drug was originally developed by Carmot Therapeutics, which Roche acquired in 2023 as part of its broader push to become a leading researcher and institution in obesity care.
If you’re interested in more content like this, check out our series on GLP-1 agonist medications from 2025. You can access part one of the full series by clicking here.
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