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.

Roche paid $3.1 billion for Carmot Therapeutics in 2023, acquiring the programme that became enicepatide and signalling its determination to challenge the companies that currently dominate obesity treatment.

Novo Nordisk built the first major modern market around GLP-1 medicines, while Eli Lilly has gained ground with drugs that target GLP-1 and GIP. Roche is entering with a similar once weekly approach and must compete on efficacy, tolerability, manufacturing capacity, supply reliability and price.

Analyst estimates show why the company is willing to invest. Vontobel’s Stefan Schneider described enicepatide as having a competitive profile in people with both type 2 diabetes and obesity. He expects a possible launch as early as 2028 and peak sales of CHF 2.5 billion. Bloomberg Intelligence analysts Michael Shah and Christos Nikoletopoulos previously assessed the drug as broadly comparable with rivals on weight loss and forecast possible approval by 2030, with peak sales of $4 billion.

Those forecasts remain contingent on clinical and regulatory milestones. Roche must demonstrate that the benefit persists, that side effects remain manageable and that the product works across the wider patient groups it hopes to serve.

Roche plans to broaden enicepatide testing from obesity and type 2 diabetes to cardiovascular disease, heart failure and other serious conditions. Manu Chakravarthy said the company wants to cover patients ranging from those without major coexisting illnesses to people with significant cardiovascular complications.

That expansion could determine whether the medicine becomes a niche competitor or a major product for Roche. Obesity treatments increasingly sit at the intersection of endocrinology, cardiology and primary care. Evidence of cardiovascular benefit could influence prescribing decisions and reimbursement discussions in Switzerland, where mandatory health insurance coverage depends on indication, clinical value and policy decisions.

The immediate milestone is the next round of trial data. Roche still needs to publish the detailed placebo adjusted results behind its headline findings and complete larger studies before seeking broad approval. It also plans to test higher doses and combinations, potentially addressing patients who need additional weight reduction or tighter blood sugar control.

For now, enicepatide has cleared an important development hurdle. The 48 week results place Roche inside the leading group of obesity drug developers, while the next trials will determine whether the Basel company can convert a promising mid stage signal into a treatment available to patients in Switzerland and beyond.