FDA issues Complete Response Letter for Disc Medicine’s bitopertin
The FDA issued a Complete Response Letter for Disc Medicine’s bitopertin NDA in EPP, saying additional evidence is needed. The agency wants Phase 3 APOLLO data before deciding.
The U.S. Food and Drug Administration has issued a Complete Response Letter for Disc Medicine’s New Drug Application for bitopertin, a treatment for erythropoietic protoporphyria (EPP). The FDA stated they could not approve Disc Medicine’s new drug application as there were uncertainties in the NDA that would need additional evidence. On this news, Disc Medicine’s stock price fell 22% on February 13, 2026.
The FDA acknowledged that Disc’s AURORA and BEACON trials demonstrated bitopertin significantly lowers whole blood metal-free PPIX, a biomarker for the condition. However, regulators concluded the trials did not sufficiently show an association between PPIX reduction and sunlight exposure-based endpoints, despite "strong mechanistic and biological plausibility" supporting the biomarker’s use.
The agency indicated it needs to review results from the ongoing Phase 3 APOLLO study before making a decision. This study is now expected to serve as the basis for potential traditional approval rather than the accelerated pathway Disc had pursued.
The company reported that enrollment for the APOLLO trial is proceeding ahead of schedule, with completion expected in March 2026 and topline data anticipated in the fourth quarter of 2026. Following these results, Disc plans to respond to the CRL, with a potential FDA decision expected by mid-2027.
Disc Medicine said it has approximately $791 million in unaudited cash, cash equivalents, and marketable securities as of December 31, 2025, which it expects will provide financial runway into 2029. Bitopertin is an oral inhibitor of glycine transporter 1 designed to modulate heme biosynthesis, and the investigational drug has not yet received approval for use in any jurisdiction worldwide.
A securities class action investigation was announced on behalf of shareholders of Disc Medicine resulting from allegations that Disc Medicine may have issued materially misleading business information to the investing public.