A COMPARISON OF PERIPHERAL-BLOOD STEM-CELL MOBILIZATION AFTER CHEMOTHERAPY WITH CYCLOPHOSPHAMIDE AS A SINGLE AGENT IN DOSES OF 4 G/M2 OR 7 G/M2 IN PATIENTS WITH ADVANCED CANCER

We used cyclophosphamide at a dose of 7 g/m2 in patients with advanced cancer and compared the efficacy of this treatment to generate peripheral blood stem cells (PBSC) with the previously reported regimen of cyclophosphamide 4 g/m2 in a similar group of patients. None of these patients received haemopoietic growth factors. Twenty-two patients received 7 g/m2 and 37 received 4 g/m2. PBSC were collected by apheresis after the leukocyte count recovered to 1.0 x 10(9)/L. The yield of colony forming unit-granulocyte macrophage (CFU-GM) was higher for the 7 g/m2 group with a median of 35 x 10(4)/kg versus 15 x 10(4)/kg body weight (BW) (p < 0.05) and higher mononuclear cell yield with medians of 4.2 x 10(8)/kg compared with 3.1 x 10(8)/kg BW (p < 0.001). The percentage of patients achieving the minimum safe level of > 15 x 10(4) CFU-GM/kg BW was higher in the 7 g/m2 cyclophosphamide group (82%) than the 4 g/m2 cyclophosphamide group (51%). The duration of significant neutropaenia was a median of 11 compared with nine days (p < 0.004) and all patients receiving 7 g/m2 required admission to hospital and intravenous antibiotic therapy compared with 44% in the 4 g/m2 group. There was one death during the period of neutropaenia after cyclophosphamide in each group. Nineteen per cent of patients required platelet transfusions after cyclophosphamide 7 g/m2 compared with 18% after 4 g/m2. We conclude that the 7 g/m2 cyclophosphamide gives a higher yield of haemopoietic progenitor cells than the 4 g/m2 but at increased clinical toxicity.