Disc Medicine, Inc. announced on October 19, 2026, that the APOLLO Phase 3 trial of its investigational drug bitopertin met all primary and secondary endpoints for the treatment of erythropoietic protoporphyria (EPP), including X-linked protoporphyria (XLP).
The APOLLO trial was a randomized, double-blind study evaluating the safety and efficacy of bitopertin versus placebo. It enrolled 183 patients aged 12 or older across the United States, Canada, Europe, and Australia. Participants were randomized 1:1 to receive 60 mg of oral bitopertin or a placebo once daily for six months.
The trial demonstrated statistical significance on both co-primary endpoints compared to placebo:
- Reduction in whole-blood metal-free protoporphyrin IX (PPIX): A reduction of 41.4% from baseline.
- Increased time in light without pain: An increase of 12.2 hours in average monthly total time during month six.
Bitopertin also achieved statistical significance on all secondary endpoints, including a reduction in the incidence rate of phototoxic reactions and an increase in cumulative total time in light without pain over the six-month period. Additionally, the drug demonstrated improvements in quality of life measures, including Patient Global Impression of Change (PGIC) and Patient Global Impression of Severity (PGIS) scores.
Safety data indicated that bitopertin was generally well-tolerated. Dizziness was the most commonly reported treatment-emergent adverse event in the bitopertin group, occurring in 50% of patients. These events were described as mild or moderate and generally transient, with no adverse events above Grade 3.
Based on these results, the company plans to resubmit a New Drug Application (NDA) to the U.S. Food and Drug Administration by the end of 2026, with an anticipated FDA decision by mid-2027.
