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Factors that predict successful remobilization after autologous hematopoietic progenitor cell transplant (aHCT) for multiple myeloma.
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: aHCT is a proven therapeutic modality in treating relapsed multiple myeloma (MM). However, previously transplanted patients may have no hematopoietic progenitor cells (HPC) left in storage. Methods: Collection of HPC after aHCT was studied in 221 MM patients who underwent 333 mobilization attempts between 10/2000 and 06/2012. Results: The median number of CD34+ collected was 4.7 ×106/kg, with 74% of collections yielding at least 2.5×106/kg. Mobilization with chemotherapy and G-CSF was most efficient, yielding a median of 6.84×106/kg (p<0.001). Growth factor-only mobilization was least effective, with a median of 3.01×106/kg (p<0.001). The addition of plerixafor yielded a significant increase if there was a previous “poor” (<2.5×106/kg) collection (1.83 vs. 3.43×106/kg, p<0.001). In univariate statistical analysis female sex (p=0.048), platelets (PLT) ≤100×106/L (p<0.001), hemoglobin ≤11g/dL (p=0.032), and albumin ≤3.5 g/dL (p=0.003) prior to mobilization correlated with a “poor” collection. In multivariate analysis only PLT ≤100×106/L was significant (p<0.001). Of the 221 patients collected, 154 underwent subsequent aHCT. Infusion of HPC procured after previous aHCT did not yield a difference in treatment-related mortality (p=0.766). Use of only cells collected after aHCT was related to a delayed platelet engraftment ≥50×106/L (p<0.001). Conclusions: Remobilization and collection of an adequate number of HPC after previous aHCT is feasible. PLT ≤100×106/L suggest the need for plerixafor for a successful collection. Infusion of the graft procured is safe and effective, but use of only cells collected after aHCT is associated with delayed platelet engraftment >50×106/L.