Disc Medicine's erythropoietic protoporphyria drug succeeds in late-stage trial

Disc Medicine announced on October 19, 2026, that its oral drug bitopertin met all primary and secondary goals in a Phase 3 trial for erythropoietic protoporphyria (EPP), driving shares up 65% in premarket trading. In the 183-patient trial, bitopertin reduced protoporphyrin IX blood levels by 41.4% compared to placebo and was well tolerated. The success follows a prior 2026 FDA rejection of the drug. EPP is a rare blood disorder causing severe sunlight sensitivity, currently managed mainly by sun avoidance or Scenesse implants.

Phase 3 trial results for bitopertin

• ▪In a 183-patient Phase 3 trial for erythropoietic protoporphyria, Disc Medicine reported that bitopertin was generally well tolerated with no new safety concerns in patients aged 12 and older
• ▪In Disc Medicine's Phase 3 study involving 183 patients aged 12 and older, patients taking bitopertin achieved a 41.4% reduction in blood protoporphyrin IX levels compared to those on placebo
• ▪On October 19, 2026, Disc Medicine announced that its experimental oral drug bitopertin met all primary and secondary endpoints in a Phase 3 study for treating erythropoietic protoporphyria

Overview and management of erythropoietic protoporphyria

• ▪Avoiding sunlight by remaining indoors and wearing protective clothing represents the primary method used to manage erythropoietic protoporphyria
• ▪Scenesse, an under-the-skin hormone implant, is the only treatment approved in the United States for erythropoietic protoporphyria
• ▪Erythropoietic protoporphyria is a rare blood disorder causing protoporphyrin IX to accumulate in the blood, resulting in extreme sensitivity and painful skin reactions when patients are exposed to sunlight