Bortezomib and cyclophosphamide based chemo-mobilization in multiple myeloma

Hematopoietic stem and progenitor cell (HSPC) mobilization regimens in multiple myeloma typically use filgrastim (GCSF) alone or combination of GCSF with plerixafor or high-dose cyclophosphamide. Murine model and human studies have shown HSPC mobilization potential of bortezomib. A total of 37 patients underwent mobilization using bortezomib 1.3 mg/m² on day 1, 4, 8 and 11, cyclophosphamide 1 g/m² on day 8 and 9, and GCSF 10 μg/kg from day 10 (B-Cy-GCSF). This regimen was compared with our earlier cohort of patients where cyclophosphamide was given at dose of 1 g/m² on day 1 and day 2 followed by GCSF 10 μg/kg from day 4 (Cy-GCSF). In B-Cy-GCSF group, median CD34 cells collected were 9.21 × 10⁶/kg (range 4.95-17.1) while in the Cy-GCSF cohort, the median CD34 cell yield was 8.2 × 10⁶/kg (0.4-24.2). Target CD34 cells yield of 5 × 10⁶/kg was achieved with single apheresis in 58.6% of patients after B-Cy-GCSF mobilization as compared to 44.3% in Cy-GCSF group (p = 0.07). Three patients failed mobilization after Cy-GCSF, while no patients failed mobilization in bortezomib group. Addition of bortezomib to Cy-GCSF mobilization showed a trend towards increased CD34 collection and reduced need for apheresis sessions.