Chugai Pharmaceutical is walking away from a weight-loss bet and picking up a shelved nerve-disease one instead. The Tokyo-listed drugmaker said on September 28 that it is stopping clinical development of emugrobart, an antibody designed to clear latent myostatin and delivered by injection under the skin, in obesity, and that its partner Roche is ending development of the molecule altogether. Chugai, whose antibody Roche has been developing under the code GYM329, is set to receive back every license right Roche held on the asset.
The obesity call rests on an interim look at the Phase 2 GYMINDA trial, which tested emugrobart added on top of a GLP-1/GIP receptor agonist in patients who were obese or overweight. That interim analysis found the pre-specified, clinically meaningful weight-loss goal was unlikely to be reached. Chugai says tolerability in the trial was good and no new safety signals turned up, so this is a case of a drug that behaved but didn't move the scale enough, not one flagged for safety.
The rights handover opens a second, separate story: spinal muscular atrophy. Roche announced in March 2026 that it was discontinuing emugrobart development in SMA and in facioscapulohumeral muscular dystrophy. Chugai now says it has found reason to support running a Phase 3 trial in SMA, citing the drug's subcutaneous delivery, its safety profile, its pharmacodynamics, clinical signals including long-term data, and refinements to Phase 3 trial design. The company describes itself as preparing to restart development, with an eye toward possibly out-licensing the program to a third party. Nothing here is a decision to run a new trial, let alone a signed license: Chugai is at the preparation stage, and the FSHD indication that Roche also flagged in that March announcement is not mentioned as part of any restart.
| Indication | Status | Basis |
|---|---|---|
| Obesity | Discontinued by Chugai; Roche ending all development of the drug | Phase 2 GYMINDA interim analysis found the pre-specified, clinically meaningful weight-loss target unlikely to be met; tolerability was good with no new safety signals |
| Spinal muscular atrophy (SMA) | Chugai preparing to restart development, possibly through a third-party license | Subcutaneous delivery, safety profile, pharmacodynamics, clinical signals including long-term data, and an improved Phase 3 trial design |
| Facioscapulohumeral muscular dystrophy (FSHD) | Roche announced discontinuation in March 2026; no restart announced | Roche announced ending development in both SMA and FSHD in March 2026 |
On the money side, Chugai says the obesity discontinuation has no effect on the consolidated earnings forecast for the year ending December 2026 that it published on January 29. The company is not abandoning the broader anti-obesity chase either: it says it is pressing on with drug discovery research across multiple modalities aimed at unmet needs in existing anti-obesity treatment, and plans to move several other development candidates into clinical trials over the next few years.
For now, the concrete change is narrow but clean: one obesity program is over, its licensing partner is walking away entirely, and the rights are due to head back to Tokyo. What happens next in SMA, a self-run Phase 3, a third-party licensee, or something else, is the open question Chugai has put on its own desk, not Roche's.