Allogeneic T-reg therapy CK0804 granted FDA orphan drug designation for the treatment of MF

On January 6, 2026, the U.S. Food and Drug Administration (FDA) granted orphan drug designation to CK0804, an allogeneic regulatory T-cell (T-reg) therapeutic for the treatment of patients with myelofibrosis. This cellular therapy is designed to preferentially bind its ligand, CXCL12, which is overexpressed in the bone marrow and spleen in myelofibrosis. In the target tissue, the T-regs mediate resolution of local and systemic inflammation through a non-major histocompatibility-restricted mechanism.

The designation is based on results from a phase Ib trial (NCT05423691), in 13 patients aged 55–84 years (median, 68 years) with myelofibrosis who had failed a median of 2 prior therapies (range, 1–6), which were presented at the 67th American Society of Hematology (ASH) Annual Meeting and Exposition, December 6–9, 2025, Orlando, US. A spleen volume reduction >10% was observed in 45% of patients (n = 11 evaluable), symptom burden reduction >50% in 78% of patients (n = 9 evaluable), and improvement in transfusion burden was observed in all evaluable patients (n = 3). At median follow-up of 195 days, 10 patients were alive, 3 underwent stem cell transplant, 2 switched therapy, and the remaining patients continued ruxolitinib treatment. Responders showed decreased circulating levels of TGFβ1/2, FGF, PDGF, sCD40L, reduced plasma and bone marrow monocytes, and normalized bone marrow myeloid-to-erythroid ratios.