TRANSPLANTATION OF THE BONE MARROW FROM A HLA-COMPATIBLE UNRELATED DONOR AFTER IMMUNOABLATIVE CONDITIONING IN CHILDREN WITH ACQUIRED APLASTIC ANEMIA UNRESPONSIVE TO COMBINED IMMUNOSUPPRESSIVE THERAPY: PRELIMINARY RESULTS

Aim. To analyze the efficiency of transplantation of the bone marrow from a HLA-compatible unrelated donor and continued immunosuppressive therapy (IST) in children with aplastic anemia (AA) unresponsive to 2 courses of IST. Subjects and methods. The study enrolled 14 children aged 2-16 years (median 9 years). A control group comprised 26 patients in whom IST was continued. The median interval between the diagnosis of AA and transplantation was 26 months (9-156 months). The conditioning regimen consisted of thoracoabdominal irradiation in a dose of 2 Gy, fludarabin (Flu) 100-150 mg/m(2), cyclophosphamide (Cy) 100-200 mg/kg, antithymocyte globulin (ATG) in 11 patients and Flu, Cy, and ATG in 3. A graft-versus-host reaction was prevented with mycophenolate mefetil in all the patients, tacrolimus in 11, and cyclosporin A in 3. Donors were compatible for high-resolution typing of 10/10 and 9/10 alleles in 8 and 6 patients, respectively; the source of a transplant was bone marrow in 13 patients and granulocyte colony-stimulating factor-mobilized peripheral blood precursors in one case. Results. Thirteen patients achieved primary engraftment after single transplantation; one patient did after repeat transplantation. Grades I to II graft-versus-host reaction (GVHR) developed in 9 patients; post engraftment life-threatening infections in 3, extensive chronic GVHR in 2, circumscribed GVHR in 7. All fourteen hemopoietic cell transplant recipients followed for a median 17.5 months (range 1-71 months) were survivors. Conclusion. The likelihood of good survival after unrelated transplantations in AA is much higher than that after continued IST: 100% versus 15 +/- 11%.