PMC

AML blast mobilization and phenotype. (a) Clinical trial schema. Patients with relapsed or refractory AML received G-CSF 10 mcg/kg daily for 8 days. Plerixafor (P) IV was administered on days 3–8. On days 4–8, Mitoxantrone 8 mg/m²/day, Etoposide 100 mg/m²/day and Cytarabine 1000 mg/m²/day (MEC) chemotherapy was administered 4 h after plerixafor. Peripheral blood samples were collected at baseline, after G-CSF only on day 3 (pre-P) and at 2, 4, 6 and 24 h after IV plerixafor administration. Complete blood counts including total leukocytes and blast (CD45^dim/SSC^low) counts were determined at each time point by flow cytometry. Mobilization of total CD45⁺ leukocytes (b) and CD45^dimSSC^lo AML blasts (c) to the peripheral blood over time after administration of a single dose of plerixafor at 0.24, 0.32, 0.42, 0.56 or 0.75 mg/kg. Mean fold changes from baseline with SEM are shown. (d) Mobilization of total CD45⁺ leukocytes and CD45^dimSSC^lo AML blasts to the peripheral blood over time from all evaluable patients enrolled in the trial. Mean fold changes from baseline with SEM are shown. Statistical comparisons were performed using a paired parametric Student's t-test. (e) The expression of CXCR4 on peripheral blood AML blasts was determined by flow cytometry using anti-CXCR4 monoclonal antibody clones 12G5 and 1D9. Mean fold changes in CXCR4 relative mean fluorescent intensity (RMFI) from baseline with SEM are shown. Statistical comparisons were performed using a paired parametric Student t-test. (f) Expression of clone 12G5 of CXCR4 (n=29), clone 1D9 of CD184 (n=29), CD114 (G-CSF receptor; n=17), CD49f (n=15) and Ki67 (n=10) on AML blasts. The RMFI or percentage of positive Ki67 cells with SEM are shown. Statistical comparisons were performed using a paired parametric Student's t-test. *P<0.05, **P<0.01 and ***P<0.001.