Percentage of Philadelphia chromosome (Ph)-negative and Ph-positive cells found after autologous transplantation for chronic myelogenous leukemia depends on percentage of diploid cells induced by conventional-dose chemotherapy before collection of autologous cells

We collected peripheral blood mononuclear cells and bone marrow cells soon after recovery from conventional-dose chemotherapy-induced myelosuppression and transplanted these cells into advanced chronic myelogenous leukemia (CML) patients after treating these patients with 120 mg/kg cyclophosphamide, 750 mg/m² VP-16, and 1,020 cGy of total body irradiation (TBI). Of the 10 late chronic-phase patients and the eight accelerated-phase CML patients evaluable posttransplant, 90% and 87%, respectively, remain alive posttransplant, whereas none of the three blast crisis CML patients given this therapy remain alive posttransplant. We measured the percentage of Philadelphia chromosome (Ph)-negative cells in the autologous cells collected after conventional- dose chemotherapy-induced myelosuppression before autologous transplant and in the marrow of these same CML patients after autologous transplantation of these cells into recipients treated with the cyclophosphamide, VP-16, and TBI. A direct correlation (correlation coefficient = 0.91) was observed between the level of Ph⁺ cells in the transplanted cells and the percentage of Ph⁺ marrow cells after transplant in 21 patients so transplanted. The data show that the chance of generating cytogenetic remissions posttransplant depends on the percentage of diploid cells in the preparations of autologous cells used for transplant and the stage of disease of the patients at the time of collection of the autologous cells.