Optimization of conditioning therapy for leukemia prior to BMT. I. Optimal synergism between cyclophosphamide and total body irradiation for eradication of murine B cell leukemia (BCL1)

Abstract

The doses of chemotherapy and radiotherapy and the sequence-dependent influence of CY administration and total body irradiation (TBI) on the eradication of murine B cell leukemia (BCL1) were investigated. Tumor-bearing BALB/c mice were treated with either CY followed by TBI (CY/TBI) or in the reverse (TBI/CY) at different time intervals after injection of 10(6) BCL1 cells. The presence of residual tumor cells after cytoreduction was assessed in secondary BALB/c recipients by monitoring leukemia-free survival. The anti-leukemic effect of CY followed by TBI was significantly better than TBI followed by CY. The survival of secondary adoptive recipients inoculated with 10(5) spleen cells obtained from mice treated with CY/TBI was 54% (57 of 105) compared with 25% (25 of 98) of recipients inoculated with 10(5) spleen cells obtained from mice treated with TBI/CY (p = 0.0001).