This follows an interim review of the safety and tolerability data from the ongoing trial by an independent Data Monitoring Committee ('DMC') and its support of Summit's plans to extend the clinical trial.
Summit has now applied for regulatory approval to extend PhaseOut DMD from the UK Medicines and Healthcare products Regulatory Agency and Ethics Committee, and has submitted the necessary regulatory updates to the US Food and Drug Administration.
These submissions are intended to facilitate the transition of patients participating in PhaseOut DMD onto an open-label extension phase at the end of the initial 48-weeks of dosing with ezutromid without a cessation in dosing.
The extension phase will be used to gather long term safety and efficacy data and is expected to last until ezutromid either receives marketing approval in the relevant country or its development is discontinued.
Ralf Rosskamp, MD, Chief Medical Officer of Summit commented: "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.
"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."
In addition to the extension phase of the trial, the regulatory submissions also include the addition of a safety arm to allow for the enrolment of patients who have previously taken part in Phase 1 clinical trials of ezutromid, but who did not meet the inclusion criteria for PhaseOut DMD.
Although regulatory approval for the safety arm is being sought, the timing for inclusion of these patients into the trial is to be determined.