Predicting hematopoietic stem cell mobilization failure in patients with multiple myeloma: a simple method using day 1 CD34+ cell yield

Early and reliable prediction of the likelihood of achieving adequate stem cell collection for autologous stem cell transplantation (ASCT) in patients with multiple myeloma (MM) would improve collection efficiency, prevent unnecessary aphereses, and permit appropriate treatment alterations. No previous study has reported a threshold CD34+ cell collection quantity on Day 1 or 2 of leukapheresis that could predict successful stem cell collection. We performed a retrospective analysis of all MM patients undergoing first attempt of stem cell collection at our institution from 2001 through 2008. Recursive partitioning analysis was used to identify Day 1 or Day 1+2 CD34+ collection quantity that predicted failure to reach target ≥ 2 × 10(6) CD34+ cells/kg within five days of collection. Totally, 172 patients were included in the analysis. Patients underwent mobilization with G-CSF or G-CSF+ chemotherapy. 23 of 172 patients (13.4%) failed to collect sufficient (≥ 2 × 10(6) CD34+ cells/kg) CD34+ cells after five days of apheresis: 22 of 29 who collected ≤ 0.70 × 10(6) CD34+ cells/kg and 1 of 143 who collected > 0.70 × 10(6) CD34+ cells/kg (75.9% vs. 0.7%, P < 0.001) on Day 1. Collection failure occurred in 23 of 30 patients who collected ≤ 1.54 × 10(6) CD34+ cells/kg and 0 of 142 who collected >1.54 × 10(6) CD34+ cells/kg (76.7% vs. 0%, P < 0.001) on Days 1 + 2. Day 1 CD34+ cell collection quantity identifies patients unlikely to achieve adequate collection for ASCT. Patients who collect ≤ 0.70 × 10(6) CD34+ cells/kg on day 1 could be considered for treatment modifications to improve CD34+ collection, such as early administration of plerixafor or large volume apheresis.