Disc Medicine says bitopertin hit all endpoints in Phase 3 APOLLO trial for EPP

Disc Medicine, Inc. (NASDAQ:IRON) reported on October 19, 2026 that its Phase 3 APOLLO trial of bitopertin in erythropoietic protoporphyria (EPP), including X-linked protoporphyria (XLP), met its goals. The trial met all its primary and secondary endpoints.¹

The study design was described in the company's filing: APOLLO was a randomized, double-blind pivotal Phase 3 trial evaluating bitopertin against placebo in adults and adolescents aged 12 or older with EPP or XLP, enrolling 183 patients across the United States, Canada, Europe, and Australia. Patients were stratified by baseline light tolerance and geography and assigned evenly to a daily 60 mg oral dose of bitopertin or placebo over a six-month period.¹

On results, the company said bitopertin achieved statistical significance on both co-primary endpoints versus placebo, including a 41.4% reduction in whole-blood metal-free PPIX from baseline (p<0.0001) and a 12.2 hour increase in average monthly total time in light without pain during month 6 (p=0.0010).¹ The drug also met all secondary endpoints, including reduced phototoxic reaction rates over six months (p<0.0001), increased cumulative time in light without pain (p<0.0001), and improved sunlight exposure time to prodrome in adults (p=0.0077).¹ Quality of life measures also improved, with better Patient Global Impression of Change and Severity scores (both p<0.0001).¹

On safety, the filing noted dizziness was the most common treatment emergent adverse event in the bitopertin group, affecting 50% of patients, generally mild to moderate and transient, with no adverse events above Grade 3.¹

Based on these results, Disc Medicine plans to resubmit a New Drug Application to the FDA by the end of 2026, with an FDA decision anticipated by mid-2027.¹ Disc obtained global rights to bitopertin under a license agreement from Roche in May 2021.¹