Comparable engraftment kinetics following peripheral-blood stem-cell infusion mobilized with granulocyte colony-stimulating factor with or without cyclophosphamide in multiple myeloma

Purpose: To compare, in the setting of tandem auto-transplantations for multiple myeloma (MM), two established methods of peripheral-blood stem-cell (PBSC) procurement with chemotherapy or hematopoietic growth factor alone. Materials and Methods: Between June 1994 and July 1995, 44 patients with MM were randomized to PBSC mobilization with either granulocyte colony- stimulating factor (G-CSF) 16 μg/kg (group 1; n = 22) or high-dose cyclophosphamide (HDCTX) 6 g/m² plus G-CSF 5 μg/kg (group 21 n = 22). All 44 patients received melphalan 200 mg/m² with their first autograft and 32 patients proceeded to a second transplantation. Results: Group 2 required a significantly longer time interval for completion of PBSC collection than group 1 (median, 22 v 8 days; P = .0001), greater frequency of hospitalization (100% v 32%; P = .0001), and increased transfusion of platelets (86% v 18%; P = .0001) and packed RBCs (86% v 55%; P = .02). Likewise, the incidence of fever and pneumonia/sepsis were higher in group 2 (P = .02 and P = .04, respectively). Surprisingly, despite greater CD34 cell quantities infused in group 2, median recovery times of granulocytes (both > 500/μL and 2,500/μL) and platelets (both > 50,000/μL and > 100,000/μL) were similar (all P > .7). Posttransplant toxicities were also similar. Conclusion: Compared with HDCTX plus G-CSF, high-dose G-CSF alone is associated with lower morbility, shorter duration of PBSC mobilization, and comparable hematopoietic recovery after transplantation, which should result in significant reduction. Considering the relatively limited antitumor activity of HDCTX (10% with ≤50% tumor cytoreduction), PBSC ohm with HDCTX should be limited to selected patients with persistent MM despite induction chemotherapy.