MA08.07 Prospective Sequential Counts of Total CTC or cKIT+CTC in Advanced NSCLC with 1st Line Chemotherapy (POLICE)

Abstract

Circulating tumor cells (CTCs) have been reported prognostic and predictive in non-small cell lung cancer (NSCLC) and a few of other cancer types. In 1st line setting, whether EPCAM+CK+CD45- CTC and/or stem cell-like cKIT+EPCAM+ CK+CD45- CTC enumeration and dynamic changes can be prognostic and/or predictive to standard chemotherapy need further investigation in Chinese patients with NSCLC. A prospective study on the CTC enumeration in advanced NSCLC with 1st line chemotherapy (POLICE) was started by China Thoracic Oncology Group (CTONG). Patients with NSCLC naïve for systemic regimens were enrolled since August 2013. CTCs were detected by Cell Search Platform and identified as positive for EPCAM+CK+CD45- phenotype. CD117 (cKIT) marker was added to test the frequency of stem cell-like cKIT+EPCAM+CK+CD45- CTCs. Primary endpoints were CTC counts and its correlation with first line therapy. Totally 180 patients were enrolled. In 174 case total CTC and cKIT+CTC positive (cutoff >=1) rates were 38.5% (67/172) vs 14.3% (24/168), 21.8% (31/142) vs 6.3% (9/142), 13.7% (13/95) vs 6.4% (6/94) and 40.4% (38/94) vs 15.0% (13/93) at time-points of baseline, after first-cycle-chemo, after four-cycles-chemo and disease progression. At time immediately after first-cycle-chemo, patients in CTC=0 group got statistically higher ORR (29.0% VS 7.1%, P=0.017) and DCR (74.2% VS 42.9%, P=0.002) than in CTC>=1 group. At time after four-cycles-chemo, patients in CTC=0 group got statistically higher DCR (88.3% VS 58.3%, P=0.026) than in CTC>=1 group. At time either after first-cycle-chemo or after four-cycles-chemo, patients in CTC>=1 group got worse PFS (5.7m VS 4.0m, P=0.025; 6.3m VS 4.0m, P=0.001 ) than in CTC=0 group. At time after first-cycle-chemo, patients in groups cKIT+CTC>=1 and cKIT-CTC>=1 got worse PFSs (3.1m vs 4.0m vs 5.7m, P=0.001) and worse DCRs (44.4% vs 42.1% vs 73.9%, P=0.009) than in CTC=0 group. For 142 patients categorized into three groups of dynamic CTC decrease (17), CTC unchanged (82), and CTC increase (43), there were significant differences in terms of DCR (71.8% vs 71.6% vs 33.3%, P=0.018) and PFS (5.2m vs 5.6m vs 3.1m, P=0.037). In first line setting of advanced NSCLC, at time-points after first-cycle-chemo other than baseline, total CTC or cKIT+CTC counts could be predictive for worse DCR or PFS. CTC increase from baseline to after-first-cycle-chemo might be a strong signal for the inefficacy of first line chemotherapy in the NSCLC patients.