Optimizing Plerixafor Algorithm For Mobilization Of Peripheral Blood Stem Cells In Patients With Multiple Myeloma Requiring Tandem Transplants

Background Plerixafor is used as an adjuvant to standard G-CSF mobilization to increases CD34+ cell mobilization and decreases the need for multiple days of collection. For patients with multiple myeloma (MM) and a collection goal of ≥5 × 10e6 CD34/kg our center follows an algorithm - if day 4 absolute CD34 is ≤20 cells/µl, patients are given a single dose of plerixafor in addition to G-CSF. For CD34 counts between 20 and 30/ µl, the administration of plerixafor was physician-dependent. Methods To assess the effectiveness of our algorithm we identified 119 consecutive MM patients who had GCSF only mobilization at our center and investigated the relationship between their day 4 absolute CD34, the administration of plerixafor and the number of days of apheresis. The patients were categorized into the following groups based upon day 4 CD34 count and administration of plerixafor (P): CD34 30 noP (n=26). Results In the 30noP group, 23/26 (88%) patients reached goal (range 4.01 × 106 – 9.14 × 106 CD34/kg) on day 1. Patients with Day 4 CD34 count between 20-30/ µl were significantly more likely to collect in one day if they have received Plerixafor (P=0.002). Conclusion This data justifies revision of the threshold for plerixafor administration to patients with a day 4, CD34 count from