Allografting in patients with severe, refractory aplastic anemia using peripheral blood stem cells and a fludarabine-based conditioning regimen:: The Mexican experience

We studied the effectiveness of a fludarabine/cyclophosphamide-based conditioning regimen without anti-thymocyte globulin in 23 aplastic anemia patients who had no response to previous conventional pharmacologic treatment. Patients received oral busulphan 4 mg/ kg/day/2 days, IV cyclophosphamide 350 mg/m(2)/day/3 days, and fludarabine 30 mg/m(2)/day/ 3 days. For GVHD prophylaxis, patients received MTX 5 mg/m(2) days +1, +3, +6, and +11 and oral cyclosporin A (CyA) 5 mg/kg/day, starting on day -1. Peripheral blood stem cell products were used with a median dose of 5.5 x 10(6) CD34(+)/kg. The patients were followed for an average of 25 months. By a median of day +11, an ANC > 0.5 x 10(9)/L was reached; and by day +12, the platelet count had reached >20,000 x 10(9)/L. Acute grade I-II GVHD occurred in 4 patients, whereas limited chronic GVHD presented in 6 cases. Twenty-one patients (91.3%) achieved engraftment. Two patients failed to engraft, and 4 developed late rejection; 2 of these individuals died, 2 have survived with high transfusion requirements, whereas 2 received a second peripheral blood stem cell infusion and achieved sustained engraftment. Currently 21 (91%) of the 23 patients are alive, whereas 19 of 21 (90%) remain in complete remission. The average cost was about USD 15,000 for this kind of reduced-intensity allotransplant. Reduced-intensity stem cell transplantation represents an affordable alternative to traditional more cytotoxic conditioning for severe aplastic anemia (SAA) patients. Long-term effects however, remain to be evaluated.