MOBILIZATION OF CIRCULATING HEMATOPOIETIC STEM-CELLS WITH GRANULOCYTE-COLONY-STIMULATING FACTOR AFTER CHEMOTHERAPY IN PATIENTS WITH MULTIPLE-MYELOMA

Due to the relatively low tumour cell contamination of peripheral bloo d in patients with multiple myeloma, autologous transplantation of cir culating stem cells may have theoretical advantages over autologous bo ne marrow transplantation. In four patients with multiple myeloma who where considered potential candidates for autologous stem cell transpl antation G-CSF (600 mug/day) was administered following chemotherapy i n order to maximally increase the number of circulating progenitor cel ls during haematopoietic rebound and to facilitate progenitor cell har vest by leukapheresis. In two previously untreated patients the admini stration of G-CSF following chemotherapy according to the UVA protocol (ultralan, vincristine, adriamycin) greatly increased circulating hae matopoietic stem cells from 247 to 7552 CFU-GM/ml in patient 1 and fro m 173 to 6361 CFU-GM/ml in patient 2, which by far exceeded the increa se in progenitor cells following chemotherapy alone, namely only to 59 4 and 317 CFU-GM/ml in patient 1 and patient 2, respectively. In two r epeatedly pretreated patients, the combination of UVA and G-CSF was mu ch less effective. Progenitor cells increased from 144 to 735 CFU-GM/m l in patient 3 and only from 222 to 232 CFU-GM/ml in patient 4. In bot h cases, however, mobilization of haematopoietic progenitor cells by G -CSF following cyclophosphamide (50 and 70 mg/kg body weight, respecti vely) led to much higher CFU-GM peak values (5324 in patient 3 and 224 5 in patient 4), thus allowing an adequate harvest of mononuclear cell s and CD 34+ cell numbers to achieve, in all probability, the prompt a nd complete reconstitution of haematopoiesis in case of transplantatio n. The combination of UVA and G-CSF is an effective strategy to mobili ze haematopoietic progenitor cells in previously untreated patients wi th multiple myeloma, but seems to be relatively ineffective in patient s who have received prior chemotherapy. Due to its higher efficacy the combination of cyclophosphamide and G-CSF is the preferred mode of tr eatment in such patients.