Determinants of Higher Pre-Apheresis CD34+ Count in Patients Undergoing Autologous Hematopoietic Stem Cell Mobilization
Authors: Chiattone Alexandre , Saliba Rima M , Chiattone Viviane C. , Tang XiaoWen , Hamerschlak Nelson , Maadani Farzaneh , Qazilbash Muzaffar H. , Popat Uday , Kebriaei Partow , Champlin Richard , Hosing Chitra M , DeLima Marcos 
Published: October 2019

Abstract
Abstract 4387
Absolute peripheral blood (PB) pre-apheresis CD34+ count has been shown to predict the CD34+ yield/Kg in patients undergoing autologous stem cell mobilization and apheresis. Determining correlates of PB pre-apheresis CD34+ counts would facilitate identifying patients that may be at high risk of mobilization failure.

Methods.
A total of 851 consecutive autologous apheresis procedures were performed at M.D. Anderson Cancer Center between January 2005 and December 2009. We randomly selected half (N=413) of this study population to serve as a study sample (described in table), and preserved the remaining for validation studies. In this study population, we observed that 96% of patients with PB pre-apheresis CD34+ counts of >40/μL collected >2×106 CD34+cells/Kg on the first day of apheresis. We sought to determine patient and disease characteristics that are associated with higher PB pre-apheresis CD34+ counts (>40/μL). These factors included patient age (quartiles), gender, weight (quartiles), diagnosis (Multiple Myeloma vs. Hodgkin's and Non-Hodgkin's Lymphoma), disease status at transplant (remission vs. active disease), number of prior chemotherapy regimens (< 2 vs. ≥2), blood count on day of collection: hemoglobin level (≤10 vs. >10 g/dL), WBC (<4 vs. ≥ 4 ×109/L), absolute neutrophil count [ANC] (< vs.≥ median), and platelet count (≤150 vs. <150 ×109/L); and number days (≤ vs. > median) from the beginning of mobilization to the first apheresis procedure.

Results.
On univariate analysis, shorter duration from beginning of mobilization therapy to first day of apheresis (odds ratio [OR] =4.7, p <0.001), and weight >95 Kg (OR=1.8, p=0.01), were significantly associated with a PB CD34+count >40/μL; whereas a diagnosis of Multiple Myeloma (OR=0.5, p=0.002), age >60 years (OR=0.6, p=0.009), pre-apheresis WBC <4 × 109/L (OR=0.5, p=0.004) and ANC (< median p=0.003) were significantly associated with PB CD34+ counts of ≤ 40/μL. These factors, with the exception of age, remained significant on multivariate analysis. Shorter duration of mobilization (OR=8.1, p<0.001) had the strongest association with PB CD34+ count >40/μL. A diagnosis of Multiple Myeloma was associated with lower PB CD34+ count in patients who had a shorter mobilization course (OR=0.3, p<0.001), but not in those who took longer to mobilize. Lower WBC and ANC counts were associated with lower PB CD34+ count, and this effect was more pronounced for patients who had both low WBC and ANC (OR=0.4, p=0.001) than for those who had low ANC but high WBC count (OR=0.5, p=0.025). Weight >95 Kg was still associated with higher PB CD34+ count, (OR=1.9, p 0.01). There was no association between PB CD34+ count and any of the remaining factors evaluated.

Conclusion:
Our data suggest that patients who take longer to mobilize, have low WBC and [ANC] pre-apheresis might benefit from early intervention with novel mobilization strategies.
Totals may vary because of missing data.

Disclosures:
Popat: Otsuka: Research Funding.