GADD45A and intrahepatic cholangiocarcinoma: In this study, we preliminarily confirmed that (1) lenvatinib had excellent antitumor effects in ICC cell lines and ICC PDX models; (2) lenvatinib inhibited ICC cell proliferation through induction of cell cycle arrest; (3) Gadd45a, a DNA damage-inducing gene, was the key factor in the regulation of the cell cycle by lenvatinib; and (4) patients with high expression of Gadd45a had a better prognosis.