Safety and efficacy of total body irradiation, cyclophosphamide, and cytarabine as a conditioning regimen for allogeneic hematopoietic stem cell transplantation in patients with acute lymphoblastic leukemia

Disease relapse still greatly interferes with the success of allogeneic hematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukemia (ALL). This study retrospectively evaluated the long-term safety and efficacy of a conditioning regimen consisting of total body irradiation (TBI; 12 Gy), cyclophosphamide (CY; 60 mg kg ^-1, two doses), and high-dose cytarabine (Ara-C; 2 g m ^-2; four doses) for patients with ALL. Fifty-five patients (median age: 31-years old) were evaluated. Stem cells were from human leukocyte antigen-identical siblings in 22 patients and from alternative donors in 33. There were no cases of early death before engraftment, and 100-day transplant-related mortality was 7.3%. With a median follow-up period of 9.6 years, 5-year overall and disease-free survival were 63.2% (95% CI: 46.5-79.9%) and 63.6% (95% CI: 47.1-80.1%) in patients with complete remission, respectively, both of which were significantly higher than the values of 27.3% (95% CI: 8.7-46.0%) and 22.7% (95% CI: 5.3-40.1%) for patients in advanced stages (P < 0.01). These results suggest that TBI and CY (TBI-CY) plus Ara-C could be a feasible and effective conditioning regimen for adult patients with ALL both in remission and in advanced stages, and a future study to compare this combination therapy with TBI-CY is required.