Roche has reported mid-stage results that put its lead obesity candidate closer to the front of a fast-moving race dominated by Eli Lilly and Novo Nordisk. The Swiss group said its once-weekly injectable Roche CT-388 obesity drug achieved up to 22.5% placebo-adjusted weight loss at 48 weeks in a phase 2 trial among participants who adhered to the treatment regimen.
When the analysis included participants who did not fully adhere to the plan, the placebo-adjusted effect was 18.3%. Roche added that a longer treatment period is likely to further improve outcomes.
CT-388 is a dual GLP-1/GIP receptor agonist, designed to regulate blood glucose and reduce appetite. That places it in the same class as Lilly’s blockbuster Zepbound (tirzepatide, also sold as Mounjaro for diabetes), not Zyprexa (an unrelated antipsychotic).
Roche CT-388 Obesity Drug Data Supports Phase 3 Push
Roche said the phase 2 readout supports the design choices behind two larger phase 3 trials, which are due to start this quarter. The company noted that the weight-loss curve had not plateaued by week 48. Roche executives framed the continuing downward trajectory as a potential differentiator if it holds up in larger studies.
Analysts also noted the competitive positioning. Jefferies said the “headline” efficacy looks broadly in line with Zepbound’s performance range, based on what has been released so far.
For healthcare leaders and payers, the key questions will go beyond weight-loss percentages. The phase 3 programme will need to clarify tolerability, discontinuation rates, cardiometabolic outcomes, and real-world persistence, all of which influence formulary decisions and total cost of care.
Carmot Deal and a Broader Metabolic Pipeline
CT-388 entered Roche’s portfolio through its $2.7 billion acquisition of Carmot Therapeutics in late 2023, a deal that signalled Roche’s intent to build scale quickly in metabolic disease.
Roche has said it now has six candidates in clinical trials for obesity and related conditions such as type 2 diabetes and hypertension, with ambitions to bring multiple products to market by 2030. The company has also pursued partnerships to broaden its metabolic franchise, including a high-value collaboration with Zealand Pharma on an obesity candidate, reflecting a strategy of combining internal R&D with external innovation.
The commercial stakes remain enormous. Analysts continue to project the obesity market could approach $150 billion a year in the early 2030s, driven by rising demand, expanding indications, and competition over pricing and access. For Roche, CT-388 is now a pivotal asset in a catch-up effort that will be judged on phase 3 execution, supply readiness, and differentiation in a crowded GLP-1 landscape.