Fludarabine, amsacrine, high-dose cytarabine and 12 Gy total body irradiation followed by allogeneic hematopoietic stem cell transplantation is effective in patients with relapsed or high-risk acute lymphoblastic leukemia.

In this prospective study, we examined the toxicity and efficacy of an intensified conditioning regimen for treatment of patients with relapsed or high-risk acute lymphoblastic leukemia who undergo allogeneic hematopoietic stem cell transplantation. Fifteen patients received fludarabine 30 mg/m(2), cytarabine 2000 mg/m(2), amsacrine 100 mg/m(2) on days -10, -9, -8 and -7, anti-thymocyte globulin (ATG-Fresenius) 20 mg/kg body weight on days -6, -5 and -4 and fractionated total body irradiation 2 x 2 Gy on days -3, -2 and -1 (FLAMSA-ATG-TBI) before allogeneic hematopoietic stem cell transplantation. At the time of hematopoietic stem cell transplantation, 10 patients were in complete remission (8 CR1; 2 CR2), 3 with primary refractory and 2 suffered from refractory relapse. All patients achieved a complete remission after hematopoietic stem cell transplantation; and after a median follow-up time of 1091 days (range, 334-1554 days), nine patients (60%) are alive and free from disease, including three patients with prior refractory disease. Three patients died due to treatment-related mortality. The most frequent and severe conditioning-related toxicities observed in 9 out of 15 patients were grade III/IV infections according to common toxicity criteria. Thus, conditioning with the FLAMSA-ATG-TBI regimen is a feasible and effective alternative for patients with relapsed or high-risk acute lymphoblastic leukemia.