Summit Plans to Extend Study of Ezutromid as Treatment for Duchenne Muscular Dystrophy

Summit Therapeutics has confirmed plans for an extension stage of a Phase 2 clinical trial evaluating ezutromid as a treatment for boys with Duchenne muscular dystrophy (DMD). 

The company based its decision on an independent Data Monitoring Committee’s interim review of ezutromid’s safety and tolerability. The extension is subject to regulatory approval.

PhaseOut DMD is a Phase 2 proof-of-concept study (NCT02858362) that will assess the safety of ezutromid and its utrophin protein modulation activity in 40 boys between 5 and 10 years old. Researchers are recruiting patients for the 48-week study. They must be ambulatory, or able to move on their own.

Investigators will use a range of measuring instruments in the study. One will be resonance imaging (MRI) to determine the amount of fat that infiltrates into muscle. Another will be muscle biopsies to determine levels of utrophin and muscle fiber regeneration.

The study, being conducted in the United States and the United Kingdom, will include a screening and baseline period lasting up to 28 days, a 48-week open-label treatment phase, and a 30-day safety follow-up period.

Summit has asked the U.S. Food and Drug Administration and the UK Medicines and Healthcare products’ Regulatory Agency and Ethics Committee to approve an extension. The request proposes that the boys receive continuous dosing of ezutromid. The extension phase, which will assess ezutromid’s long-term effectiveness and safety, will last until regulators approve the drug’s marketing, or its development is halted.

“The proposed extension phase will allow us to gather important long-term safety and efficacy data of ezutromid in patients with DMD that we believe will comprise part of a data package necessary for future applications for regulatory approval of ezutromid,” Ralf Rosskamp, MD, Summit’s chief medical officer, said in a press release. “While the PhaseOut DMD trial continues with the aim of establishing proof of concept for ezutromid, we are pleased to see that the DMC supports the trial’s extension based on their review of the safety and tolerability data to date, which includes data from patients dosed over longer periods of time than have previously been tested.”

Summit’s extension application includes a safety component that allows patients who took part in the Phase 1 trial of ezutromid, but were not eligible for PhaseOut DMD, to participate in the extension.

Ezutromid is an orally administered, small-molecule modulator of utrophin, a protein that is structurally and functionally similar to dystrophin. Dystrophin is a protein crucial to the healthy function of muscles and muscle repair that is missing in Duchenne’s patients.

DMD is a progressive muscle-wasting condition affecting about 50,000 boys and young men in the developed world. Life expectancy for those with the condition is only the late 20s.

The FDA and European Medicines Agency have already given ezutromid orphan drug status.