(P-BT-25) Regimen Specific Mobilization Kinetics During HPC(A) Collection: Time to Collection Readiness and Mobilization Characteristics

Background/Case Studies: Hematopoietic Progenitor Cell (HPC) collection requires significant coordination between service lines.  Understanding mobilization kinetics, including time to collection readiness and median collection days by regimen facilitates these coordination efforts and is valuable for patient counseling.

Study

Design/Methods: Among autologous HPC donors, white blood cell (WBC), peripheral blood CD34 counts (pre-CD34), CD34 collection yields, day 1 of collection readiness (defined as pre-CD34 count >10/μL), and total collection days were extracted and analyzed according to mobilization regimen. For collection day 1, median WBC is compared to median pre-CD34 count.  Results are presented as median (interquartile range - IQR) using relevant units.  Units expressed in days were rounded up to the nearest whole day.

Results/Findings: Key findings are presented in Table 1.  For cyclophosphamide (CTX)+G-CSF (G) (n=10 multiple myeloma) and G-CSF-only (n=14) mobilized donors, there is a close relationship between numeric collection day 1 pre-CD34 (per μL) and WBC (K/μL) counts with median ratios of 0.9 to 1.1, respectively.  Among CTX+G multiple sclerosis (MS, n=10), ifosfamide+etoposide (for patients with lymphoma; n=8) and carfilzomib+dexamethasone – cisplatin, doxorubicin, cyclophosphamide, etoposide (KD-PACE; for patients with myeloma myeloma [MM]; n=10) mobilized donors, the median (IQR) ratios were: 6.0 (4.2,5.8), 3.1 (0.6,8.1), and 4.0 (2.9,4.3), respectively.  For chemo-mobilization regimens, collection readiness in days occurred at median (IQR) 11 (10,12) for CTX-G MM, 10 (10,11) CTX-G MS, 16 (15,16) for ifosfamide+etoposide, and 20 (19,20) for KD-PACE.  Median (IQR) collection courses (in days) were shortest for CTX+G MS at 1 (1,1), KD-PACE at 1(1,2) and longest for G-CSF+plerixafor (P) MM at 3 (3,3) and CTX+G MM at 3 (2,4).  Total collection yields were similar among G-CSF, G-CSF+P, and CTX-G MM groups; day 1 collection yields were lowest among G-CSF+P and CTX-G MM.  For G-CSF based autologous stem cell mobilizations, the sensitivity and specificity of MM as predictor for plerixafor need was 94% and 50%, respectively; the negative predictive value for plerixafor need of a non-MM diagnosis was 92%.

Conclusions: Median time to collection readiness occurred by days 10, 16, and 19 among CTX-G for patients with MS, ifosfamide+etoposide for patients with lymphoma, and KD-PACE for patients with myeloma mobilized donors. Chemomobilization produced more robust pre-CD34 peaks than G-CSF or G-CSF+P mobilization.  Among G-CSF only mobilizations, the absence of MM as an underlying diagnosis was a strong predictor for non-use of plerixafor.  These findings can be utilized to facilitate coordination of services, patient counseling, and to help improve resource utilization.