A Better Mobilization Regimen for Newly Diagnosed Multiple Myeloma Patients

Abstract 4051 Introduction: What constitutes an acceptable mobilization regimen for collecting CD34+ cells depends on whether the goal of collection is to obtain a minimum number versus optimal number of cells. When treating patients with high-risk myeloma it may be important to obtain an optimal number. Here we compare retrospectively our earlier mobilization regimen, VTD-PACE, with MVTD-PACE in newly diagnosed, previously untreated multiple myeloma patients. Materials and Methods : We reviewed data for all patients who collected hematopoietic progenitor cells on Total Therapy protocols TT3a/TT3b with VTD-PACE (n=394) from February 2004 to September 2008 (138 females and 256 males, median age 59y; range 31–75), and on TT4/TT5 with MVTD-PACE (n=188) from August 2008 to May 2011 (78 females and 110 males, median age 61y, range 30–76). Based on their predicted first day collection with a large volume leukapheresis (30L processed), using our center's predictive formula (Blood 2010; 116(21):1182a), patients were stratified into 4 mobilizer types: poor (10 to 20×106) and excellent (>20×106). Variables examined included number of CD34+ cells/μl blood on day 1 and day 2 of collection (we have a minimum 2 day collection requirement), number of collection days to reach our minimum goal of 20×106 CD34+ cells/kg, and total CD34+ cells/kg collected for both chemotherapy groups. Variables for both groups stratified by mobilizer type were compared using two-tailed student's t-tests, except for the poor mobilizer group, where population size was too small for formal statistical analyses (VTD-PACE n=7, MVTD-PACE n=4), although averages were calculated. Results : There was no significant difference between VTD-PACE and MVTD-PACE for CD34+ cells/μl blood on day 1 of collection among the excellent [mean 368.9 (n=184) vs. 434.6 x106 (n=92); p-value 0.07], good [mean 138.6 (n=102) vs. 128.6 x106 (n=40); p-value 0.19], and intermediate [mean 60.1 (n=100) vs. 55.9 x106 (n=52); p-value 0.39] groups. A statistically significant difference between VTD-PACE and MVTD-PACE was found for CD34+ cells/μl blood on day 2 of collection for excellent mobilizers [mean 333.8 (n=184) vs. 460 ×106 (n=92); p-value Disclosures: No relevant conflicts of interest to declare.