Roche's enicepatide cuts HbA1c by 2.65 points and weight by 15.5% in Phase II diabetes trial

Roche announced on September 22, 2026 that its investigational once-weekly dual GLP-1/GIP receptor agonist enicepatide met both primary endpoints in the Phase II CT-388-104 trial, cutting HbA1c by 2.65 percentage points from a baseline of 8.1% and reducing body weight by 15.5% at 48 weeks in 447 adults living with type 2 diabetes and overweight or obesity.

The readout lands in the middle of one of the most fiercely contested races in drug development. Roche said it is racing alongside large drugmakers, including AstraZeneca and Amgen, to break into the lucrative obesity drug market and challenge the current leaders, Eli Lilly and Novo Nordisk. Roche is betting on next-generation treatments in a market that is expected to exceed $100 billion annually within the next decade, a projection that has drawn nearly every large pharmaceutical company into the space.

Enicepatide, also known as CT-388, is a once-weekly injection that mimics the GLP-1 and GIP hormones to reduce appetite and regulate blood sugar. It belongs to the same incretin class that turned obesity into a commercial gold rush, but Roche has positioned it as a potential best-in-disease candidate rather than a fast follower. FierceBiotech reported on September 22 that Roche framed the result as evidence of enicepatide's best-in-disease potential.

The diabetes readout follows an earlier Phase II study reported in June 2026, in which enicepatide helped overweight or obese patients without diabetes lose 22.7% of their body weight. That trial established the drug's weight-loss credentials in a population without dysregulated glucose. The new CT-388-104 study tests whether the same molecule can also deliver meaningful glycemic control in people whose blood sugar is already elevated, a question that matters for how broadly the drug can eventually be prescribed.

Key Facts

Reuters reported on September 22 that the experimental dual-acting obesity drug helped overweight or obese patients with type 2 diabetes lower blood sugar levels and lose an average 15.5% of their body weight in a mid-stage trial. Patients who received 24 milligrams of enicepatide, the highest dose, saw significant reductions in HbA1c at 48 weeks, meeting the two main goals of the study. HbA1c is a measure of blood-glucose levels over time, and clinicians use it to judge how well diabetes is controlled over months rather than days.

According to Roche's September 22 press release, the 24 mg cohort achieved a mean HbA1c reduction of 2.65% from a baseline of 8.1%. Roche said 90% of patients in that cohort reached an HbA1c level of 6.5% or lower, the diagnostic threshold for type 2 diabetes, while 62% achieved normoglycemia, defined as HbA1c below 5.7%, restoring blood glucose levels to a non-diabetic range. In patients who started with a baseline HbA1c above 8.5%, the reduction reached 4.13 points, a figure that speaks to the drug's performance in the hardest-to-treat group.

Weight loss in the 24 mg enicepatide arm averaged 15.5% at 48 weeks without a demonstrable plateau, according to Roche. The company said the safety and tolerability profile was consistent with other established incretin-based therapies, with the most common adverse events being predominantly mild to moderate gastrointestinal effects. The treatment discontinuation rate due to adverse events was 2.0% in the enicepatide arms and 0.0% in the placebo arm.

RTTNews reported on September 22 that Roche shares closed at 364.80 Swiss francs on the SIX Swiss Exchange, up 2.24%. FierceBiotech reported on September 22 that the lack of a plateau suggests deeper weight loss will be possible in longer trials. The same report noted that Lilly reported Week 40 weight loss of up to 15.3% on its own investigational candidate, retatrutide, giving investors a direct reference point for how Roche's numbers compare.

The CT-388-104 study was a 48-week randomized, double-blind, placebo-controlled Phase II trial conducted in adults living with type 2 diabetes and overweight or obesity. Roche said enicepatide met both primary endpoints, delivering dose-dependent and clinically meaningful reductions in blood glucose and body weight at 48 weeks.

Analysis

What this really means is that Roche has moved from a credible challenger to a genuine contender in the incretin field. A 2.65 percentage point HbA1c reduction on the top dose is a large effect for a once-weekly injectable, and the fact that 62% of patients on 24 mg reached a non-diabetic HbA1c range within a year is the kind of outcome that resonates with clinicians who manage type 2 diabetes every day.

The bigger picture here is that the diabetes indication may matter more commercially than the headline weight-loss number. Obesity alone is a vast market, but type 2 diabetes brings in patients, payers and cardiometabolic specialists who evaluate a drug on glycemic control as well as pounds lost. A dual GLP-1/GIP agonist that performs well on both axes can be positioned across a broader patient population than a pure weight-management product, and it gives Roche a second front on which to compete with Eli Lilly and Novo Nordisk.

Roche is framing the result as evidence of best-in-disease potential, and the comparators support that ambition without proving it. Lilly reported Week 40 weight loss of up to 15.3% on retatrutide, a figure that sits close to the 15.5% weight reduction Roche recorded at 48 weeks in a diabetes population. Cross-trial comparisons are always risky because populations, durations and dosing schedules differ, but the two numbers are close enough to make the coming Phase III readouts a real contest rather than a formality.

The cautious note is safety transparency. FierceBiotech reported on September 22 that Roche has yet to share detailed safety and tolerability data. The 2.0% discontinuation rate against 0.0% on placebo is low in absolute terms and consistent with the broader class, where gastrointestinal effects are a well-known trade-off. Even so, investors and regulators will want the full adverse-event picture before treating the efficacy figures as a complete story.

Why It Matters

For patients, the combination of deep HbA1c reduction and substantial weight loss in a single weekly injection points to a future in which type 2 diabetes and obesity are treated with the same molecule rather than separate regimens. Levi Garraway, Roche's Chief Medical Officer and Head of Global Product Development, said the company was highly encouraged by the efficacy demonstrated by enicepatide in the Phase II study, including the meaningful proportion of patients reaching normalised glucose levels within less than a year of treatment.

For the market, the result sharpens competition at the top of a category expected to exceed $100 billion annually within the next decade. Roche is racing alongside AstraZeneca and Amgen to break into that market and challenge Eli Lilly and Novo Nordisk, the two companies that currently define it. A third credible player with a differentiated dual-agonist profile would change pricing dynamics, formulary decisions and the pace of innovation across the sector.

For Roche itself, the readout is a strategic validation. The company has spent years rebuilding its late-stage pipeline, and enicepatide now anchors a cardiometabolic franchise that stretches from chronic weight management into glycemic control and cardiovascular outcomes. A drug that performs across all three would be far more valuable than a single-indication obesity treatment.

Next Up

Roche is advancing a broad late-stage development program for enicepatide, including two ongoing Phase III studies in chronic weight management known as ENITH-1 and ENITH-2. Teresa Graham, CEO of Roche Pharmaceuticals, said the company plans to initiate a Phase III glycemic-control program and cardiovascular outcomes trials in the first half of 2027.

The next milestone will be whether the Phase II encouragement survives the larger, longer and more demanding Phase III setting. Roche said it plans to start late-stage glycemic-control and cardiovascular outcomes studies in the first half of 2027, a timeline that puts the first pivotal data points several years out and keeps the competition with Eli Lilly, Novo Nordisk, AstraZeneca and Amgen firmly in view.