Cellenkos' allogeneic T regulatory cell therapy CK0801 has received Orphan Drug Designation from the U.S. Food and Drug Administration (FDA) for the treatment of aplastic anemia, a rare and life-threatening bone marrow failure disorder.
The designation, announced on April 14, 2025, provides Cellenkos with several incentives, including tax credits, exemptions from certain FDA fees for clinical trials, and the potential for seven years of market exclusivity following approval. Aplastic anemia affects approximately 1.0-2.3 per million people in the U.S., with a projected prevalence of about 5,000 patients.
"Receiving Orphan Drug Designation for CK0801 in aplastic anemia underscores the importance of bringing novel, transformative treatment options to patients suffering from this rare disease," said Dr. Simrit Parmar, Founder of Cellenkos and faculty member at The College of Medicine at Texas A&M University. "We aim to deliver a transformative therapeutic that can reduce the burden of blood and platelet transfusions in patients with aplastic anemia who have failed to respond to standard-of-care treatment."
Promising Phase 1 Results
The Orphan Drug Designation follows the publication of Phase 1 clinical trial results in NEJM Evidence last year. The trial (NCT03773393) demonstrated that CK0801, an allogeneic T regulatory (Treg) cell therapy derived from umbilical cord blood, led to durable transfusion independence lasting up to 3.5 years in patients with aplastic anemia.
The study included nine patients with bone marrow failure syndromes and found that a single infusion of CK0801 Tregs resulted in a 67% overall response rate at the one-year follow-up. Notably, 75% of aplastic anemia patients achieved partial responses, with two individuals becoming transfusion-independent within months of treatment and maintaining this independence for up to 41 months.
A key advantage of CK0801 is its administration protocol. Patients received infusions in an outpatient setting through a peripheral intravenous line without requiring hospitalization or conditioning chemotherapy.
Key Clinical Findings
The Phase 1 trial revealed several significant outcomes:
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Durable Transfusion Independence: Two out of three transfusion-dependent patients with aplastic anemia achieved complete and durable transfusion independence lasting up to 3.5 years.
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Favorable Safety Profile: CK0801 was well-tolerated with no infusion reactions or severe adverse events, and no dose-limiting toxicities were observed. The therapy does not require any additional conditioning regimen or IL-2 supplementation.
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Immunologic Impact: Infusion of CK0801 increased circulating Tregs and promoted Treg expansion within bone marrow, suggesting the therapy's potential to modulate the immune system and improve bone marrow function in patients with aplastic anemia.
Broader Applications in Bone Marrow Failure Syndromes
Beyond aplastic anemia, the Phase 1 study also included patients with myelofibrosis and myelodysplastic syndromes. In these patients, CK0801 induced meaningful improvements, including symptom relief, transfusion independence, and in one case, complete remission following an allogeneic stem cell transplant.
"These results represent a significant milestone in the treatment of aplastic anemia and potentially other bone marrow failure disorders," noted Dr. Parmar. "The durable responses we've observed suggest that CK0801 may address a critical unmet need for patients who have limited treatment options."
Current Treatment Landscape
Aplastic anemia is characterized by the bone marrow's failure to produce sufficient blood cells, leading to severe complications such as bleeding, infection, and fatigue. Current treatments include immunosuppressive therapy, growth factors, and stem cell transplantation, but these approaches are often inadequate or unsuitable for many patients.
CK0801 offers a promising new approach by using Tregs to restore immune balance and promote bone marrow function. Unlike conventional therapies, it does not require donor matching, making it potentially accessible to a broader patient population.
Path Forward
Cellenkos is advancing CK0801, its lead asset, toward a registration trial intended to support regulatory approval for the treatment of transfusion-dependent aplastic anemia. The company plans to initiate this pivotal trial in the second half of 2025.
As a clinical-stage biotechnology company based in Houston, Texas, Cellenkos focuses on developing off-the-shelf Treg cell therapies for rare inflammatory diseases and autoimmune disorders. Their Treg therapies are designed to provide powerful anti-inflammatory effects and long-lasting immune modulation without the need for donor matching.
The advancement of CK0801 represents a significant step forward in the development of novel cell therapies for rare diseases with high unmet medical needs, potentially offering new hope to patients with aplastic anemia who have exhausted conventional treatment options.
