Purpose: The two major factors associated with lack of survival after allogeneic marrow transplant for severe aplastic anemia have been graft rejection and acute graft versus host disease (GVHD). As a result, survival for patients transplanted in the 1970s was similar to 68%. Improved survival during the 1980s was primarily related to the decrease in the incidence of acute GVHD with the use of combination methotrexate and cyclosporine for GVHD prophylaxis. Although the incidence of graft rejection has not changed, the time to graft rejection has been delayed. Patients and Methods: One hundred forty children <18 years of age received a marrow transplant for severe aplastic anemia at the Fred Hutchinson Cancer Research Center between May, 1971 and June, 1991. Four recipients of syngeneic marrow received a simple marrow infusion, 119 recipients of HLA-identical family member marrow received cyclophosphamide (CY), 200 mg/kg; most recipients of alternative donor marrow received CY plus 12.0 Gy fractionated total body irradiation. GVBD prophylaxis was MTX only for 91 recipients of HLA-identical family member marrow, and was MTX plus CSP for all other allogeneic marrow patients. Estimates of graft rejection, acute and chronic GVHD, survival and event-free survival (EFS) were determined by the Kaplan-Meier method. Results: Two recipients of syngeneic marrow achieved engraftment with donor marrow infusion only and two required immunosuppression with CY. Among the 119 recipients of HLA-identical family member marrow the type of GVHD prophylaxis did not influence graft rejection but non-transfused patients had 10% incidence of rejection compared to 22% for transfused patients (p = 0.1). All patients with late graft rejection survive whereas those with early rejection usually do not. The incidence of acute GVHD was 27% and 11% for MTX recipients and MTX plus CSP recipients, respectively (p = 0.11), and the probability of chronic GVHD was 30% and 26%, respectively. Survival is 64% for recipients of MTX and 96% for recipients of MTX plus CSP (p = 0.007), but EFS was 60% and 71%, respectively (p = 0.48). Recipients of partially matched family member or unrelated marrow donor grafts have transplants complicated by infections and GVHD. Growth and development of CY only recipients is normal and several children have been born to these former patients. Conclusions: High dose CY is usually an effective preparative regimen for children with severe aplastic anemia and an HLA-identical family member marrow donor. Additional immunosuppression with anti-thymocyte globulin may result in a further decrease in graft rejection and improved EFS. Identification of a group of children who are unlikely to respond to immunosuppressive treatment could permit earlier transplantation for patients without HLA-identical family member donors available. Children who receive CY only have normal growth and development.
