Fludarabine, Cyclophosphamide and ATG Based, Reduced Intensity Conditioning for HLA-Match Sibling Donor Transplant in Severe Aplasic Anemia (SAA) - Case Report.

Allogeneic bone marrow transplantation (BMT) from an HLA-identical sibling is a curative form of therapy for patients with acquired severe aplastic anemia.

Survival has significantly improved over the past 3 decades. The actuarial risk of rejection has been reduced to about 7%. Improved results with survival in excess of 90% have been reported. Current preparative therapies are associated with early and late sequelae such as acute and chronic graft-versus-host disease (aGvHD or chGvHD, respectively) and secondary tumors. Two patients (6 years and 11 years old) with SAA, who had an HLA-identical sibling donor could not proceed with myeloablative therapy at the time of transplant due to delay in results of chromosome stability and fragility in one patient and abnormal pulmonary function in the second. Both received reduced intensity preparative regimen with Fludarabine (30 mg/m²×4 doses) Cyclophosphamide (5 mg/kg×4 doses) and rabbit ATG (1.5 mg/kg×4 doses) followed by an unmanipulated allogeneic BMT from their HLA-identical sibling donors. Graft versus host disease prophylaxis consisted of Cyclosporine from day -1 and Methotrexate 15 mg/m² on day +1 and 10 mg/m² on days +3, +6, +11 after transplant. Myeloid engraftment occurred on day +15 and day +28. The time to a platelet count >20,000 unsupported was +11 days and +29 days. No transplant-related toxicities, including mucositis or alopecia, were recorded. There were no signs for aGvHD or chGvHD. The patients continue with full donor chimerism 27 months and 130 days post transplant, respectively. This data suggests that a non-myeloablative, immunosuppressive regimen is sufficient to provide a stable engraftment in the patients with SAA. This approach may be associated with decreased transplant-related short- and long-term toxicities. A larger study is needed to fully evaluate the outcome and the toxicity associated with this conditioning.