Dose-Intensive CK0804 Regimen Reduces Spleen Volume and Transfusion Needs in JAK Inhibitor-Resistant/ Suboptimal Myelofibrosis with Thrombocytopenia

• Dose-intensive CK0804 Treg regimen appears to overcome JAK inhibitor treatment resistance
• Durable spleen volume reduction and decreased transfusion burden are associated with reduced inflammatory biomarkers following CK0804 Treg therapy
• Cellenkos will initiate phase 2 trial of CK0804 in JAK ihnibitor resistant/ suboptimal myelofibrosis

ORLANDO, Fla., Dec. 10, 2025 /PRNewswire/ -- New data from a dose‑intensive regimen of Cellenkos' CK0804 regulatory T cells (Tregs) in patients with myelofibrosis who had an inadequate response to standard-of-care therapy were presented at the 67th American Society of Hematology (ASH) Annual Meeting & Exposition in Orlando, Florida (Abstract #5602).

Key findings

• Spleen volume reduction (SVR): Among 11 evaluable patients, SVR10 was achieved in 45%, SVR25 in 27%, and SVR35 in 18%.
• Transfusion requirements: All three transfusion‑dependent patients showed a reduction in monthly transfusion needs by the end of the study.
• Symptom improvement: A greater than 50% reduction in total symptom burden was observed in 78% of patients (9 of 11).
• Biomarker profile: Clinical responses correlated with reductions in FGF, sCD40L, PDGF‑AA, and PDGF‑AA/BB.
• Thrombocytopenic subgroup: All three thrombocytopenic patients tolerated the intensive CK0804 regimen; all had a 100% reduction in symptom burden, and two achieved SVR10.

A total of 13 patients received CK0804: nine on a monthly infusion schedule and four on a dose‑intensive regimen consisting of weekly infusions for four weeks followed by monthly infusions for five additional doses, with a fixed number of 100 million Tregs per infusion.

"Patients almost immediately started to feel better, and they do not want to stop CK0804 infusions," said Mehrdad Abedi, MD, Principal Investigator, Professor of Medicine, University of California, Davis. "Even in patients with thrombocytopenia and poor renal function, CK0804 was well tolerated, and patients reported improvements in abdominal distention and early satiety, which paralleled reductions in spleen volume."

"Intensifying the CK0804 Treg regimen appears to counter the high inflammatory burden in myelofibrosis," said Simrit Parmar, MD, MSCI, Founder of Cellenkos. "The depth and durability of responses in thrombocytopenic patients who had failed or had suboptimal benefit from prior JAK inhibitor therapy are particularly encouraging and pave way for phase 2 trial."

About CK0804
CK0804 is an investigational, allogeneic, off‑the‑shelf Treg cell therapy designed to exploit the CXCR4/CXCL12 axis to suppress inflammatory cytokines implicated in the pathogenesis of myelofibrosis. Derived from clinical‑grade umbilical cord blood and manufactured using Cellenkos' proprietary CRANE^® process, CK0804 does not require HLA matching and is supplied cryopreserved with a shelf life of more than two years, enabling rapid, on‑demand use. The product is administered intravenously through a peripheral line in an outpatient setting.

About Cellenkos, Inc.
Cellenkos, Inc. is a clinical‑stage biotechnology company developing allogeneic, off‑the‑shelf T regulatory (Treg) cell therapies for autoimmune and inflammatory diseases. Tregs are key immune cells that resolve pathologic inflammation and maintain immune homeostasis; seminal work on Tregs was recognized with the 2025 Nobel Prize. Cellenkos' proprietary CRANE^® platform isolates highly suppressive, stable Tregs from allogeneic umbilical cord blood, providing several advantages:

• No plasticity: Cord blood–derived Tregs remain stable suppressor cells without converting to pro‑inflammatory phenotypes, even in hostile inflammatory environments
• Tissue targeting: Expression of chemokine receptors such as CXCR3, CXCR4, CXCR7, and LFA‑1 allows precise homing to inflamed tissues
• Off‑the‑shelf availability: No HLA matching or donor conditioning is required; cryopreserved products are ready‑to‑use for outpatient administration
• Scalable manufacturing: A single cord blood unit can yield multiple therapeutic doses

Cellenkos operates an in‑house cGMP manufacturing facility in Houston, Texas, overseeing the full value chain from process development through clinical supply.

For more information about Cellenkos, please visit www.cellenkosinc.com
Contact: [email protected]

SOURCE Cellenkos, Inc.