Disc Medicine Refines Trial Design for EPP Drug, Targets Accelerated FDA Approval

Disc Medicine has finalized the design for its confirmatory trial of bitopertin, a drug candidate aimed at addressing a rare blood disorder, erythropoietic protoporphyria (EPP). This step comes after discussions with the U.S. Food and Drug Administration (FDA), which resulted in the addition of a co-primary endpoint to the trial. The new design aims to strengthen the case for accelerated approval of the drug.
The biotech company intends to file for accelerated approval of bitopertin in the second half of the year. This decision follows an agreement with the FDA to use the reduction of protoporphyrin IX (PPIX) as a surrogate endpoint for the regulatory process. PPIX, a key indicator of EPP, plays a significant role in the disorder’s characteristic photosensitivity.

Disc’s discussions with the FDA prompted adjustments to the study design to confirm bitopertin’s efficacy. Previously, the FDA approved the use of “average monthly time in sunlight without pain” at the end of a six-month treatment period as the primary endpoint. This measure remains intact but is now joined by a co-primary endpoint, reflecting the FDA’s evolving input.
The additional endpoint focuses on changes from baseline in whole blood metal-free PPIX after six months of treatment. Will Savage, M.D., Ph.D., Disc’s chief medical officer, elaborated on the decision during a conference call with investors.
According to Savage, elevating this measure to a co-primary endpoint underscores its importance in assessing the drug’s impact. “The elevation of this endpoint to co-primary is an indication that regulators understand the importance of the role of PPIX,” he explained. “It is highly objective, and we are optimistic that we can meet this endpoint, so we feel that it strengthens the design of the confirmatory trial favorably.”

To gain approval, Disc must achieve both primary endpoints in its trial. The company noted that enrollment for the 150-patient study would be well underway by the time the FDA reviews the application for accelerated approval.
This confirmatory trial design reflects a collaborative effort between Disc Medicine and the FDA, with an aim to validate bitopertin’s therapeutic potential in addressing EPP. Disc Medicine has finalized the confirmatory trial design for its rare blood disorder drug candidate, bitopertin, after discussions with the FDA. The trial now includes a co-primary endpoint, focusing on metal-free PPIX levels. This strengthens the study’s rigor as the company seeks accelerated approval and aims to validate bitopertin’s efficacy for EPP.