Circulating Immature Myeloid Cells (ImC) Levels Correlate with Clinical Cancer Stage and Cyclophosphamide (CTX) Treatment (49.15)

Tumor-associated immune suppression is known to be an important contributor to cancer progression. One such mechanism is the abnormal accumulation of ImC in the peripheral blood. Although both tumor burden and CTX-induced accumulation of ImC are well described in animal studies, human studies have been limited. Thus, the goal of our study was to determine whether levels of ImC in whole blood correlate with clinical cancer stage in cancer patients (pts). Flow cytometry analyses were performed on whole peripheral blood from newly diagnosed solid tumor pts. ImC population was defined as lineage−CD33+HLA-DR−CD11b+. Peripheral blood specimens from 14 normal healthy controls and 35 cancer pts (stages: I, n=3; II, n=9; III, n=9; IV, n=14), revealed greater ImC in cancer pts vs. normal (3.21% vs. 1.47%; p=.002). Stage IV pts had the highest percentage of ImC (4.39%). Initial results from stage II-III breast cancer pts (n=10) treated with preoperative chemotherapy showed that CTX treatment was associated with significant increases in circulating ImC compared with baseline (2.91% vs. 10.57%; p=0.001), and also when compared to taxane chemotherapy independent of G-CSF (10.57% vs. 3.25%; p=0.00025). In conclusion, overall ImC levels correlate with clinical cancer stage and CTX treatment leads to transient increases in ImC in breast cancer pts.