A 21-year-old woman diagnosed with a rare mature γδ T-cell leukemia achieved a continuous complete remission lasting more than four years following an allogeneic umbilical cord blood transplantation, according to a case report detailed by researchers at Tohoku University Hospital and Tohoku Medical and Pharmaceutical University Faculty of Medicine in the Journal of Clinical and Experimental Hematopathology.
The patient initially presented with severe neutropenia and abnormal lymphocytes carrying a complex genetic profile, including a KMT2A::AFDN translocation and a BCL11B mutation. Hematologists at Tohoku University Hospital administered six cycles of a CHOP chemotherapy regimen—consisting of cyclophosphamide, doxorubicin, vincristine, and prednisolone—which successfully induced an initial complete remission.
Relapse and Salvage Therapy
Approximately one year after completing the initial chemotherapy course, the patient experienced a hematological relapse characterized by the reappearance of abnormal γδ T cells in both her bone marrow and peripheral blood. To counter the disease progression, clinicians administered salvage chemotherapy using the CHASE regimen, which includes cyclophosphamide, cytarabine, a steroid, and etoposide. According to the medical report, this salvage therapy successfully achieved a second complete remission after three cycles.
Given the patient’s young age and the high-risk, aggressive nature of this specific T-cell neoplasm, the clinical team pursued an allogeneic hematopoietic stem cell transplantation with curative intent. Because human leukocyte antigen (HLA) matched sibling or unrelated donors were unavailable, physicians selected a single unit of umbilical cord blood as the graft source.
Transplantation and Recovery
The transplant procedure utilized a graft with alleles mismatched at one of the eight HLA loci in both directions. The myeloablative conditioning regimen comprised cytarabine at 8 g/m², cyclophosphamide at 120 mg/kg, and total body irradiation administered at 12 Gy in six fractions. The infused cell dose measured 3.1 × 10⁷ per kilogram of total nucleated cells and 0.76 × 10⁵ per kilogram of CD34⁺ cells. Graft-versus-host disease prophylaxis relied on a combination of tacrolimus and short-term methotrexate.
The post-transplantation recovery proceeded largely without major complications. Neutrophil engraftment was documented on day 20, and complete donor chimerism was confirmed on day 38. The patient experienced Grade I acute graft-versus-host disease, which manifested as a limited stage 2 skin rash that resolved successfully with corticosteroid treatment. She was discharged from the hospital on day 80 in good overall condition.
Physicians gradually tapered the tacrolimus regimen until completely discontinuing it on day 578. According to the published findings, the patient has maintained continuous complete remission for more than four years post-transplantation, exhibiting sustained full donor chimerism and no clinical evidence of disease recurrence.