Antitumor agent-163 (Compound 3) serves as a photosensitizer in molecular-targeted photodynamic therapy (MT-PDT) aimed at carbonic anhydrase IX (CAIX). Under illumination at 540 nm, Antitumor agent-163 inactivates CAIX protein through singlet oxygen generation without affecting internal standard proteins such as α-tubulin, β-actin, and proliferating cell nuclear antigen (PCNA). It induces cell membrane damage and reduces cell viability with IC50 values of 0.2 μM for A549 and 0.05 μM for U87MG. Furthermore, Antitumor agent-163 demonstrates antitumor activity in mouse models.