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.
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