Disc Medicine said its experimental drug bitopertin met all primary and secondary endpoints in the Phase 3 APOLLO trial in adults and adolescents with erythropoietic protoporphyria, including X-linked protoporphyria.
The company plans to resubmit a New Drug Application to the U.S. Food and Drug Administration by the end of 2026 and anticipates a decision by mid-2027.
The randomized, double-blind trial enrolled 183 patients aged 12 or older across the United States, Canada, Europe and Australia. Participants received either 60 milligrams of oral bitopertin or placebo once daily for six months.
Bitopertin met both co-primary endpoints, producing a 41.4% reduction in whole-blood metal-free protoporphyrin IX, or PPIX, versus placebo and adding 12.2 hours of pain-free light exposure during month six. The respective p-values were below 0.0001 and 0.0010.
Secondary results showed statistically significant reductions in phototoxic reactions and increases in cumulative pain-free light exposure over six months. Adult participants also experienced improved sunlight tolerance before early warning symptoms developed.
Exploratory measures showed improvements in patients’ assessments of their condition and changes in disease impact.
Disc said bitopertin was generally well tolerated, with no new safety signals. Dizziness occurred in 50% of treated participants and was generally transient and mild or moderate. No treatment-emergent adverse events exceeded Grade 3.
Bitopertin inhibits glycine transporter 1 and is designed to alter heme production, reducing PPIX accumulation.
The drug remains investigational and is not approved anywhere. Disc licensed global rights from Roche in May 2021 and plans to present detailed APOLLO findings at a future medical conference.
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