CD8A and neoplasm: Among the TOP2 poisons tested (Fig. 5a, red highlighted), we chose etoposide as a candidate to inhibit the EMT/β-catenin/STT3/PD-L1 axis in both CSCs and non-CSCs for the following reasons: (1) etoposide is one of the few cytotoxic compounds with CSC-targeting ability39; (2) etoposide treatment does not induce significant changes in the number of CD8+ lymphocytes in vivo40,41, the major immune cell population in the body’s defense against cancers1,7; (3) etoposide, especially at lower doses, induces tumor-specific immunity in preclinical models42,43.