Stem cell mobilization and autologous stem cell transplantation after pretreatment with bendamustine, prednisone and bortezomib (BPV) in newly diagnosed multiple myeloma.

Introduction: Reliable information on stem cell toxicity and mobilization of stem cells for autologous stem cell transplantation (SCT) after induction treatment with a combination of bendamustine, prednisone and bortezomib (BPV) is missing.

Materials And Methods: A retrospective analysis of peripheral blood stem cell mobilization and autologous SCT was performed in 35 patients with MM who had received at least one cycle of a BPV-induction therapy consisting of bendamustine 60 mg/m(2) on days 1 and 2, bortezomib 1.3 mg/m(2) on days 1, 4, 8 and 11 and prednisone 100 mg on days 1, 2, 4, 8 and 11 between October 2008 and May 2014. The mobilization regimen consisted of cyclophosphamide 4 g/m(2) and G-CSF (2 × 5 μg/kg). Apheresis was started as soon as peripheral CD34(+) counts exceeded 20 × 10(6)/L with a harvest target of 8 × 10(6) CD34(+)/kg. The minimal accepted target was 2 × 10(6) CD34(+)/kg. The transplantation conditioning therapy consisted of melphalan 200 mg/m(2).

Results: A median number of two (range 1-5) BPV cycles were given. The majority of patients (n = 31, 89 %) responded with two sCR, five nCR, 11 VGPR and 13 PR after BPV induction. Three patients had MR, and one SD. Stem cell mobilization and harvest were successful in all patients. In 19 of 35 patients (54 %), a single apheresis was sufficient to reach the target. The median number of aphereses was one (range 1-4), and the median CD34(+) cell-count/kg was 13.5 (range 3.2-33.1)  × 106. All patients received an autologous SCT. Engraftment was successful in 34 of 35 patients. The median time to a leukocyte count >l × 10(9)/L was 11 days, and the time to untransfused platelet count of >50 × 10(9)/L was 13 days. Thirty-four patients (97 %) responded after the autologous SCT with 11 sCR, two CR, seven nCR, seven VGPR and seven PR. The progression-free survival at 18 months was 87 %, and overall survival was 92 %.

Conclusion: Stem cell mobilization and autologous SCT are feasible in MM patients who have received BPV-induction therapy .