Disc Medicine reports durable anemia responses in RALLY-MF Phase 2
Disc Medicine has presented updated data from two clinical programmes at the European Hematology Association annual meeting in Stockholm, reporting durable anemia responses in myelofibrosis and sustained disease-marker reductions in a rare photosensitivity disorder.
The headline disclosure centred on RALLY-MF, the company's ongoing Phase 2 open-label study of DISC-0974, a subcutaneous hepcidin-suppressing antibody, in patients with myelofibrosis and anaemia. The dataset, drawn from 50 evaluable patients as of a 27 April cut-off, showed response rates that held up across baseline transfusion status and regardless of whether patients were receiving concomitant JAK inhibitor therapy.
RALLY-MF data
Among the 31 non-transfusion-dependent patients, 55% achieved a haemoglobin increase of at least 1.5 g/dL sustained over 12 or more weeks, meeting the protocol's major response definition, and 68% met the lower overall response threshold. In the transfusion-dependent cohort with a low burden, 64% achieved transfusion independence over a 16-week window; in the high-burden subgroup, 50% reached transfusion independence over 12 weeks and 88% reduced transfusion requirements by at least half.
DISC-0974 also produced reductions in hepcidin exceeding 75% from baseline, with corresponding increases in serum iron, consistent with its mechanism of targeting the hepcidin-ferroportin axis. Clinically meaningful improvements in the FACIT-Fatigue patient-reported outcome scale were observed in non-transfusion-dependent and low-burden patients, correlated with haemoglobin change. Diarrhoea was the only treatment-related adverse event reported in two or more subjects, and the company characterised the overall safety profile as well-tolerated.
Disc also updated investors on the bitopertin programme in erythropoietic protoporphyria. The HELIOS open-label extension, which enrolled 86 adults and adolescents from earlier BEACON and AURORA trials, showed sustained reductions in protoporphyrin IX after more than 2.5 years of exposure and significant improvement in light tolerance and time-to-prodrome measures. A Phase 3 APOLLO readout is expected in the fourth quarter of 2026 and, following a Type A meeting with the FDA, has been confirmed as a potential basis for responding to an existing complete response letter and could support traditional approval if successful.
Regulatory and competitive context
John Quisel, president and chief executive, said the EHA data set the company up for a "catalyst-rich second half of the year," with End of Phase 2 FDA discussions for DISC-0974 targeted before year-end and initial data from the RESTORE-PV Phase 2 trial of DISC-3405 in polycythemia vera also expected in the fourth quarter.
Myelofibrosis anaemia is a crowded and commercially validated segment. Approved JAK inhibitors including ruxolitinib, fedratinib and pacritinib address disease burden but leave anaemia poorly managed in many patients, driving demand for add-on approaches. Luspatercept, marketed by Bristol Myers Squibb and Merck, is the most directly competitive asset, having demonstrated anaemia benefit in myelofibrosis. Disc's data showing responses in patients already on JAK inhibitors, if confirmed in a pivotal study, would be a commercially relevant differentiator, as this population represents the majority of treated patients. The company has not yet disclosed a Phase 3 design for DISC-0974, and investors will watch End of Phase 2 discussions closely for guidance on endpoint selection and trial size.
Bitopertin faces a narrower but less contested path in EPP, a rare condition with no approved therapies targeting the underlying PPIX pathway in many markets. The APOLLO readout will be closely watched by the rare-disease investor community, given the regulatory complexity introduced by the prior CRL.