Cellenkos has received orphan drug designation from the US Food and Drug Administration (FDA) for its investigational CK0804 regulatory T cell (Treg) therapy to treat myelofibrosis, a rare blood cancer.
The condition has an estimated prevalence of 25,000 patients in the US and an annual incidence of one to three new cases per 100,000 people.
CK0804 is an allogeneic, off‑the‑shelf Treg cell therapy.
In a clinical study involving 13 patients with myelofibrosis (median age 68 years), who had failed a median of two therapies previously, 45% of 11 evaluable patients achieved more than 10% spleen volume reduction.
Symptom burden was reduced by more than 50% in 78% of nine evaluable patients. All three evaluable patients showed improvement in transfusion burden.
These results were presented at the 67th Annual Meeting of the American Society of Hematology in December 2025.
At a median 195-day follow-up, ten patients were alive; two changed therapy class, three underwent stem cell transplant, and others continued initial ruxolitinib treatment.
Responders showed reduced plasma and bone marrow monocytes, decreased inflammatory cytokines (TGFβ1, TGFβ2, FGF, PDGF, sCD40L), and normalisation of bone marrow myeloid to erythroid ratio.
Cellenkos' founder Dr Simrit Parmar said: “Receiving orphan drug designation is an important milestone in the clinical development of CK0804 for myelofibrosis and underscores our commitment to advance CK0804 into Phase II trials to address the unmet need for patients who have not responded to currently available therapies.
“The observed increase in IL-10 and decreases in TGFβ levels in CK0804 responders, together with reductions in pathogenic monocytes in plasma and bone marrow, support the disease-modifying potential of CK0804 Tregs as a distinct and differentiated therapeutic class in myelofibrosis.”
In April 2024, Cellenkos signed a sponsored research agreement with the Icahn School of Medicine at Mount Sinai Hospital, New York, US, to investigate the use of CK0804 for myelofibrosis.
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