Successful application of nonmyeloablative transplantation for paroxysmal nocturnal hemoglobinuria

Objective. Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal hematopoietic stem cell disorder that manifests as hemolytic anemia, venous thrombosis, and deficient hematopoiesis. Although allogeneic hematopoietic stem cell transplantation is considered the only curative therapeutic meas ure, transplant-related mortality is not negligible. Several studies suppor ted the use of nonmyeloablative stem cell transplantation (NST) for patient s of advanced age or with organ dysfunction, Hence, we used NST in a PNH pa tient who suffered from acute renal failure due to repeated episodes of hem olysis, Materials and Methods We performed NST using a conditioning regimen consist ing of cladribine 0.11 mg/kg X 6, busulfan 4 mg/kg x 2, and rabbit anti-thy mocyte globulin 2.5 mg/kg x 2. He received peripheral blood stem cells from his human leukocyte antigen-matched brother. Prophylaxis against graft-vs- host disease was performed with cyclosporine A alone, Chimerism of peripher al blood mononuclear cells was evaluated serially using short tandem repeat analysis and flow cytometry, Results. No meaningful regimen-related toxicities were documented. Donor ch imerism of 90 to 100% was achieved on day 14 and thereafter. The patient is doing well, without any recurrence of hemolysis 6 months after transplant, Follow-up chimerism studies confirmed stable and functioning donor-type he matopoiesis, Conclusions. NST may become a safe and curative approach in patients with P NH, Further studies are needed to establish the role of NST for treatment o f PNH. (C) 2001 International Society for Experimental Hematology, Publishe d by Elsevier Science Inc.