Edison's orphan drug misses the mark in Phase II

Edison Pharmaceuticals' in-development rare disease treatment missed its primary endpoint in a mid-stage trial, denting the company's plans for an expansive take on CNS R&D.

The drug, EPI-743, is an oral therapy designed to treat disorders of energy metabolism, including Rett syndrome, a neurodevelopmental disorder that affects one in every 10,000 to 15,000 live births, the company said.

In a placebo-controlled Phase II trial on 24 Rett patients, the treatment missed its primary endpoint of significantly improving patient-reported disease scores, but Edison is looking on the bright side, highlighting its performance in secondary measures as signs of promise. Despite missing its main goal, EPI-743 spurred a statistically significant increase in head growth among girls with the disorder, improving one of the established metrics of Rett, the company said.

Edison hasn't decided whether to roll the drug into Phase III for the disorder, but the biotech plans to "engage with health authorities, patient foundations, and the clinical/research community in the next several months to define the next steps that may ultimately lead to new options for children with Rett syndrome and other mitochondrial diseases," Chief Medical Officer Matthew Klein said in a statement.

Despite the setback, the biotech is still chugging along with mid-stage studies to chart EPI-743's potential in its lead indications, the rare CNS ailments Friedreich's ataxia and Leigh syndrome.

Last year, Edison struck a deal with Dainippon Sumitomo under which it handed over Japanese rights to EPI-743 and the Phase I EPI-589 in exchange for $50 million up front and up to $460 million more. The partners kicked off a Phase IIb/III study on EPI-743 in the Leigh indication in January, and the drug picked up the FDA's coveted fast-track status for Friedreich's ataxia in March.

Earlier this year, Edison and Dainippon expanded their partnership to team up on drug discovery, with the latter kicking over another $50 million and promising nearly $4 billion more in milestones.

- read the statement (PDF)