Taiho's DMD Drug Candidate Fails to Meet Primary Endpoint in Phase 3 Trial

Taiho Pharmaceutical's investigational treatment for Duchenne muscular dystrophy (DMD) has failed to demonstrate significant improvement in functional motor test results, missing the primary endpoint in a phase 3 clinical trial. The study, known as REACH-DMD, was conducted in Japan and involved 82 male patients with DMD aged 5 years and older.

Trial Design and Results

The double-blind study was divided into two cohorts: an ambulatory group and a non-ambulatory group. Participants received either TAS-205 (also known as pizuglanstat), an orally administered candidate, or a placebo twice daily for 52 weeks.

The primary endpoint for the ambulatory cohort measured the mean change from baseline in the time it takes patients to rise from the floor. According to the July 8 release, TAS-205 failed to demonstrate a statistically significant difference compared to placebo in this crucial functional test over the 52-week treatment period.

Mechanism of Action and Drug Development

TAS-205 is designed to selectively inhibit hematopoietic prostaglandin D synthase (HPGDS), an enzyme related to inflammation responses in DMD patients. This approach targets the underlying inflammatory processes associated with the disease, which causes progressive muscle weakness due to the body's inability to produce normal dystrophin protein.

The development of TAS-205 represents Taiho Pharmaceutical's efforts to address the unmet medical needs in DMD, a serious genetic condition that primarily affects young males.

Future Implications and Next Steps

Taiho Pharmaceutical, a subsidiary of Otsuka Holdings, has not yet disclosed its future plans for TAS-205 following this setback. The company stated that further findings from the REACH-DMD study are expected to be presented at an upcoming academic conference.

While the primary endpoint was not met, it's worth noting that in an earlier phase 2 study, no obvious differences in the incidences of adverse events were reported between the treatment and placebo groups. However, detailed safety data from the phase 3 trial, particularly for the non-ambulatory group, have not been released at this time.

This disappointing outcome highlights the ongoing challenges in developing effective treatments for DMD and underscores the complexity of addressing this devastating neuromuscular disorder.