Low-risk intensive therapy for multiple myeloma with combined autologous bone marrow and blood stem cell support

To improve the safety of autotransplantation for myeloma, peripheral blood stem cell (PBSC) collection was attempted in 75 previously treated patients after the administration of high-dose cyclophosphamide (HD-CTX; 6 g/m2) with or without granulocyte-macrophage colony- stimulating factor (GM-CSF). Sixty patients subsequently received melphalan 200 mg/m2 (57 patients) or melphalan 140 mg/m2 and total body irradiation (850 cGy) (3 patients) supported by both autologous bone marrow and PBSC; 38 patients received GM-CSF posttransplantation. Among 72 patients undergoing PBSC apheresis, “good” mobilization (greater than 50 colony-forming units granulocyte-macrophage [CFU-GM] per 10(5) mononuclear cells) was achieved when prior chemotherapy did not exceed 1 year and when GM-CSF was used post-HD-CTX; similarly, rapid platelet recovery to 50,000/microL within 2 weeks was associated with “good” PBSC mobilization. These same variables also predicted for rapid engraftment after autotransplantation, so that hematologic recovery (granulocytes greater than 500/microL and platelets greater than 50,000/microL) proceeded within 2 weeks among the 37 patients with “good” PBSC collection. As a result of rapid neutrophil recovery (greater than 500/microL) within a median of 2 weeks, infectious complications both post-HD-CTX and posttransplant were readily manageable, resulting in only one treatment-related death post-HD-CTX. The cumulative response rate (greater than or equal to 75% cytoreduction) for all 75 patients was 68%, with 12-month event-free and overall survival projections of about 85%. Using both bone marrow and PBSC together with GM-CSF, autotransplants are safe and appear effective in myeloma, especially when prior therapy had been limited to less than 1 year. More than 80% of transplanted patients achieved complete hematologic recovery within a median of 1 month posttransplant (granulocytes greater than 1,500/microL; platelets greater than 100,000/microL; hemoglobin greater than 10 g%), thus providing sufficient hematopoietic reserve for further chemotherapy in the event of posttransplant relapse.