Addition of high-dose Ara-C to the BMT conditioning regimen reduces leukemia relapse without an increase in toxicity

The optimal conditioning regimen for allogeneic BMT for hematological malignancies is still to be determined. We used a conditioning regimen including high-dose Ara-C (HDAC)/CY/TBI for patients at high risk for leukemic relapse (regimen A, Ara-C 3 g/m² every 12 h for six doses followed by CY 45 mg/kg for 2 days and TBI 13.2 Gy in eight fractions) and a standard CY/TBI conditioning regimen for patients at low risk (regimen B, CY 60 mg/kg for 2 days and TBI 13.2 Gy in eight fractions). We analyzed 55 patients treated with regimen A (group A) and 36 patients with regimen B (group B). Relapse rates (10.9% in group A, 2.9% in group B, P = 0.23), 5-year overall (53.2% in group A and 60.8% in group B, P = 0.26) and disease-free (47.7% in group A and 60.8% in group B, P = O.11) survival rates were not significantly different between these groups. Although group A consisted of high-risk patients. Regimen-related toxicities were not significantly different between the two groups. This result suggests that adding HDAC to CY/TBI conditioning regimen may reduce leukemic relapse and improve survival without increasing regimen-related toxicities.