As EV and subpopulations of PD-L1EV/PD-L2EV provide tumor-supporting characteristics within the tumor microenvironment [2–5], their pre- and post-CT levels were analyzed with respect to presence or absence of specific CTC subpopulations including AKT2, ALK, AR, AURKA, BRCA1, KIT, MET, EGFR, ERCC1, ERBB2, ERBB3, KRT4, mTOR, NOTCH 1, PARP1, PIK3CA, SRC. The gene discussed is ERCC1; the disease is neoplasm.