N-((1S,9S)-9-Ethyl-5-fluoro-2,3,9,10,13,15-hexahydro-9-hydroxy-4-methyl-10,13-dioxo-1H,12H-benzo(de)pyrano(3',4':6,7)indolizino(1,2-b)quinolin-1-yl)-2-hydroxyacetamide

CAS 1599440-33-1

N-((1S,9S)-9-Ethyl-5-fluoro-2,3,9,10,13,15-hexahydro-9-hydroxy-4-methyl-10,13-dioxo-1H,12H-benzo(de)pyrano(3',4':6,7)indolizino(1,2-b)quinolin-1-yl)-2-hydroxyacetamide (CAS 1599440-33-1) has a chemical story that connects molecular identity with practical chemistry. CAS 1599440-33-1 is DXd, an exatecan-derived DNA topoisomerase I inhibitor best known as the cytotoxic payload of trastuzumab deruxtecan, originally DS-8201a. DXd belongs to the camptothecin/exatecan lineage. Topoisomerase I normally relieves torsional stress through transient DNA breaks; inhibitors stabilize cleavage complexes so replication converts a reversible event into damaging lesions. DXd's modern significance comes from antibody-drug-conjugate engineering: a potent payload is connected through a cleavable linker to a targeting antibody, separating target recognition, intracellular release and cytotoxic action into coordinated molecular functions.

The exact CAS identity matters because related salts, stereoisomers, intermediates and finished medicines can play very different roles even when their names look closely related.