Stem cell factor in combination with filgrastim after chemotherapy improves peripheral blood progenitor cell yield and reduces apheresis requirementsin multiple myeloma patients: A randomized, controlled trial

Stem cell factor (SCF) has been shown to synergize with filgrastim to mobil ize CD34(+) cells into the peripheral blood. To determine if addition of SC F to chemotherapy and filgrastim reduces the number of leukaphereses requir ed to achieve a target yield of 5 x 10(6) CD34(+) cells/kg, 102 patients wi th multiple myeloma were randomized to receive mobilization chemotherapy wi th cyclophosphamide (4 g/m(2)) and either SCF (20 mu g/kg/d) combined with filgrastim (5 mu g/kg/d) or filgrastim alone (5 mu g/kg/d), administered da ily until leukaphereses were completed. After collection, patients were tre ated with myeloablative therapy supported by autologous peripheral blood pr ogenitor cell (PBPC) infusion and filgrastim (5 mu g/kg/d). There was a sig nificant difference between the treatment groups in the number of leukapher eses required to collect 5 x 10(6) CD34(+) cells/kg (median of 1 v 2 for SC F + filgrastim and filgrastim alone, respectively, P = .008). Patients rece iving the combination of SCF plus filgrastim had a 8-fold greater chance of reaching 5 x 106 CD34(+) cells/kg in a single leukapheresis compared with patients mobilized with filgrastim alone, The median CD34(+) cell yield was significantly increased for the SCF group in the first leukapheresis (11.3 v 4.0 x 10(6)/kg, P = .003) and all leukaphereses (12.4 v 8.2 x 106/kg, P = .007). Total colony-forming unit-granulocyte-macrophage (CFU-GM) and mono nuclear cell counts were also significantly higher in the SCF group in the first leukapheresis and in all leukaphereses. As expected for patients mobi lized to an optimal CD34(+) cell yield, the time to engraftment was similar between the 2 treatment groups. Cells mobilized with the combination of SC F plus filgrastim were thus considered effective and safe for achieving rap id engraftment Treatment with SCF plus filgrastim was well tolerated, with mild to moderate injection site reactions being the most frequently reporte d adverse events. There were no serious allergic-like reactions to SCF. The addition of SCF to filgrastim after cyclophosphamide for PBPC mobilization resulted in a significant increase in CD34(+) cell yield and a concomitant reduction in the number of leukaphereses required to collect an optimal ha rvest of 5 x 10(6) CD34(+) cells/kg. (C) 1999 by The American Society of He matology.