Successful treatment of severe aplastic anemia by bone marrow transplantation from HLA nonidentical family members: preliminary results utilizing cyclophosphamide and 600 cGY fractionated total body irradiation.

We have performed bone marrow transplants on four children with severe aplastic anemia who lacked an human leukocyte antigen (HLA)-identical sibling donor. Patients were prepared with cyclophosphamide and 600 cGy fractionated total body irradiation, and then received marrow from a parent donor mismatched for one (two patients), two (one patient), or three (one patient) HLA antigens. All four patients engrafted. One died early of acute graft-versus-host disease. The three others showed sustained complete hematopoietic reconstitution. Two are alive and hematologically normal 43-87 months after transplant. Both have had acute and chronic graft-versus-host disease (CGVHD), and one of the two remains on immunosuppressive drugs. The fourth died at 48 months after transplant of CGVHD. The previous experience with HLA-incompatible marrow transplants is reviewed, and the rationale for this preparative regimen is discussed. Cyclophosphamide and 600 cGy fractionated total body irradiation is an effective preparative regimen for children with severe aplastic anemia receiving transplants from HLA-nonidentical parental donors, allowing engraftment and full hematologic reconstitution.