Roche obesity drug cuts weight by 15.5% in mid-stage trial

Roche’s experimental obesity injection reduced average body weight by 15.5% in 48 weeks, giving the Basel based pharmaceutical group a strong early result in one of the industry’s fastest growing markets.

The result came from patients who were overweight or obese and also had type 2 diabetes. Participants receiving the highest 24 milligram dose of enicepatide, formerly known as CT-388, also recorded a 2.65% reduction in HbA1c, the standard measure of longer term blood sugar control. Roche said weight loss had not reached a plateau by the end of the 48 week study.

The company is positioning enicepatide against products from Eli Lilly and Novo Nordisk, whose medicines have reshaped treatment for obesity and diabetes. Roche’s candidate is a once weekly injection that activates both GLP-1 and GIP, two hormones involved in appetite, metabolism and glucose regulation. Lilly’s Zepbound uses the same broad hormone pathway.

The early findings arrive as analysts estimate that the global weight loss drug market could eventually reach $150 billion. Roche shares closed 0.19% lower in Zurich on September 23, 2026, suggesting investors are waiting for more detailed evidence before changing their expectations.

The highest enicepatide dose lowered HbA1c by 2.65%, alongside the 15.5% average weight reduction. That combination matters for the patients Roche studied, since excess weight and poorly controlled type 2 diabetes often reinforce each other.

Roche said about 62% of participants reached the normal glycemic range within 48 weeks. Manu Chakravarthy, Roche’s senior vice president and global head of cardiovascular, renal and metabolism product development, said the treatment produced weight loss without hypoglycemia, a potentially dangerous drop in blood sugar.

The trial’s safety signal also attracted attention. Roche reported that 2% of patients stopped treatment because of side effects after 48 weeks. In a shorter mid stage trial of Lilly’s Mounjaro in patients with diabetes, reported discontinuation rates ranged from 5% to 24.5%, according to the source report. The studies were not identical, so the figures cannot establish a direct head to head comparison.

For Swiss patients and clinicians, the practical value will depend on more than a headline percentage. Doctors will need to assess sustained weight loss, glucose control, gastrointestinal side effects, dosing, access and reimbursement. Roche has yet to show the full placebo adjusted data needed to answer those questions.

Goldman Sachs analysts called the data competitive, while warning that Phase 3 trials must confirm the benefit. James Quigley and colleagues said the available results compare favourably with outcomes reported for rival medicines in late stage studies, but they want to see detailed placebo adjusted figures before drawing firm conclusions.

That caution reflects the stage of Roche’s programme. A mid stage trial can identify a promising dose and reveal important safety signals, yet larger Phase 3 studies provide the evidence regulators usually require on effectiveness, risks and consistency across broader patient groups. The current findings came from a defined population of people with type 2 diabetes who were overweight or obese.

Roche already has two late stage obesity trials underway. The company plans to expand testing in early 2027 to diabetes and cardiovascular outcomes. It is also studying higher doses and combinations with other weight loss medicines.

Teresa Graham, Roche’s pharmaceuticals chief, said the company wants to develop enicepatide both as a standalone treatment and in combinations for people who need greater weight loss or improved glycemic control. That strategy could widen the drug’s potential use, but it also raises the complexity of future trials and regulatory review.