Our data suggest that the ATM-mediated DNA damage signaling pathway might be involved in T-DXd-induced mRNA expression of CXCL9/10/11 in HER2-positive GC cells, because an ATM inhibitor (KU-55933), but not ATR and Chk1 inhibitors (VE-821 and UCN-01), selectively inhibited T-DXd-induced mRNA expression of CXCL9/10/11 (Fig. 4B). The gene discussed is CHEK1; the disease is gastric cancer.