A novel hematopoietic progenitor cell mobilization regimen, utilizing bortezomib and filgrastim, for patients undergoing autologous transplant

Adequate hematopoietic progenitor cell (HPC) collection is critical for patients undergoing autologous HPC transplant (AHPCT). Historically, 15 − 30% of patients failed HPC mobilization with granulocyte-colony stimulating factor (G-CSF) alone. Bortezomib, a proteasome inhibitor, has been shown to down regulate very late antigen-4 (VLA-4), an adhesion molecule expressed on HPCs. In this pilot study, bortezomib was administered on days −11 and −8 at a dose of 1.3 mg/m² intravenously (IV) or subcutaneously (SQ), followed by G-CSF 10 mcg/kg SQ, on days −4 to −1 prior to HPC collection (Day 1). Nineteen patients, with multiple myeloma (n = 12) or non-Hodgkin lymphoma (n = 7) undergoing AHPCT for the first time, were enrolled. Patients were excluded if they had worse than grade II neuropathy or platelet count less than 100 x 10⁹/L. Bortezomib was well tolerated and all patients had adequate HPC collections with no mobilization failures. One patient (6%) had a CD34⁺ cell count of 3.9 cells/µL on Day 1 and received plerixafor per institutional algorithm. Eleven patients completed HPC collection in 1 day and eight in 2 days. All patients underwent AHPCT and had timely neutrophil and platelet engraftment. Comparison with a historical control group of 70 MM and lymphoma patients, who were mobilized with G-CSF, showed significantly higher CD 34+ cells/kg collected in the bortezomib mobilization study group. Bortezomib plus G-CSF is an effective HPC mobilizing regimen worth investigating further in subsequent studies. J. Clin. Apheresis 31:559–563, 2016.