Disc Medicine said its Phase 3 Apollo trial of bitopertin in erythropoietic protoporphyria met all primary and secondary endpoints, with the clearest gains showing up in both lab and symptom measures.
The study enrolled 183 patients across the U.S., Canada, Europe and Australia and tested 60 mg of oral bitopertin once daily for six months. On the first co-primary endpoint, bitopertin cut whole-blood metal-free PPIX by 41.4% versus placebo, with p<0.0001. On the second co-primary endpoint, patients gained 12.2 more hours of total time in light without pain in month 6 versus placebo, with p=0.0010.
The secondary results also came in positive. Bitopertin reduced the incidence rate of phototoxic reactions over the six-month treatment period versus placebo, with p<0.0001, and increased cumulative total time in light without pain over the full treatment period, also with p<0.0001. In adults, average daily sunlight exposure time to prodrome improved versus placebo, with p=0.0077.
Patient-reported outcomes moved as well. The drug improved patient global impression of change and patient global impression of severity scores, both with p<0.0001.
Safety data showed bitopertin was generally well tolerated. Dizziness was the most common treatment-emergent adverse event, reported in 50% of patients in the bitopertin group, and it was described as mild or moderate and generally transient. There were no treatment-emergent adverse events above grade 3.
Disc said it plans to resubmit a new drug application to the FDA by the end of 2026 and expects a decision by mid-2027. The market has reacted to these announcements by moving the company's shares 0.34% to a price of $56.84. For more information, read the company's full 8-K submission here.
