CAIX-IN-2 (Compound 9o) is an inhibitor of carbonic anhydrase (CA), targeting CAIX, CA XII, and CAII with IC50 values of 5.6, 7.4, and 430 nM, respectively. This compound effectively inhibits the proliferation of cancer cells such as HCT-116, SW480, MDA-MB 231, and MCF-7, with IC50 values ranging from 14.63 to 29.33 µM. CAIX-IN-2 also integrates into DNA, causing cell cycle arrest at the G1/S phase and inducing apoptosis in MDA-MB-231 cells. Furthermore, it disrupts mitochondrial membrane potential (MMP), elevates intracellular ROS levels, leading to mitochondrial damage, and inhibits the migration of MDA-MB-231 cells. In mouse models, CAIX-IN-2 has demonstrated antitumor activity.