As Porter et al. pointed out that vigorous expansion and persistence of CART cells in vivo is a critical determinant of therapeutic efficacy [18], in this case, the CAR transgene copy number in PB ascended to peak level immediately after the beginning of CART-EGFR cell infusion, illustrating that CART-EGFR cells underwent a robust expansion in vivo, which is one of the premises of CART-EGFR cells eliminating EGFR-expressing CCA cells. Here, EGFR is linked to cholangiocarcinoma.