Contribution of chemotherapy mobilization to disease control in multiple myeloma treated with autologous hematopoietic cell transplantation

In patients with multiple myeloma (MM) undergoing autologous hematopoietic cell transplantation (auto-HCT), peripheral blood progenitor cells may be collected following mobilization with growth factor alone (GF) or cytotoxic chemotherapy plus GF (CC+GF). It is uncertain whether the method of mobilization affects post-transplant outcomes. We compared these mobilization strategies in a retrospective analysis of 968 patients with MM from the Center for International Blood and Marrow Transplant Research database who received an auto-HCT in the US and Canada between 2007 and 2012. The kinetics of neutrophil engraftment (⩾0.5 × 10 9 /L) was similar between groups (13 vs 13 days, P =0.69) while platelet engraftment (⩾20 × 10 9 /L) was slightly faster with CC+GF (19 vs 18 days, P =0.006). Adjusted 3-year PFS was 43% (95% confidence interval (CI) 38–48) in GF and 40% (95% CI 35–45) in CC+GF, P =0.33. Adjusted 3-year OS was 82% (95% CI 78–86) vs 80% (95% CI 75–84), P =0.43 and adjusted 5-year OS was 62% (95% CI 54–68) vs 60% (95% CI 52–67), P =0.76, for GF and CC+GF, respectively. We conclude that MM patients undergoing auto-HCT have similar outcomes irrespective of the method of mobilization and found no evidence that the addition of chemotherapy to mobilization contributes to disease control.