T-2513 is a potent and specific inhibitor of topoisomerase I. It acts by forming covalent bonds with the topoisomerase I-DNA complex, thereby enhancing its stability. This interaction disrupts the normal process of DNA replication and RNA synthesis, ultimately resulting in cellular apoptosis.

SN-38, a metabolite of T-2513[1], demonstrates broad cytotoxic effects across various human tumor cell lines, as shown in a Cell Cytotoxicity Assay of WiDr, HT-29, SK-BR-3, MKN-1, SK-LU-1, LX-1, KB, and HeLaS3 cells[2]. When treated with concentrations ranging from 15.1 to 111.5 ng/mL for 24 hours, SN-38 induced cytotoxicity, with GI 50 values recorded at 32.1 ng/mL for WiDr, 97.6 ng/mL for HT-29, 38.6 ng/mL for SK-BR-3, 15.6 ng/mL for MKN-1, 111.5 ng/mL for SK-LU-1, 15.1 ng/mL for LX-1, 34.0 ng/mL for KB, and 50.9 ng/mL for HeLaS3 cells, respectively.

T-2513, administered at doses ranging from 1 to 100 mg/kg, demonstrates antitumor activity against Walker-256 carcinoma in a rat model. This activity was observed in rats bearing Walker-256 carcinoma, with the study utilizing dosages of 1, 10, and 100 mg/kg. The effective dose 50 (ED50), indicating the dose at which 50% of the maximum effect is observed, was determined to be 23 mg/kg.