This invention provides a side-chain coupled compound of a
cell-binding molecule having a branched
linker and an
amanita toxin compound. [Solution] A side-chain conjugated compound of formula (I), TIFF2026097851000286.tif25170 In one embodiment, a side-chain conjugated compound is provided, in which T is a
cell-binding agent / molecule, W is a C1-C18 extension unit, and D is an
amanita toxin, or an
isotope of a
chemical element, or a pharmaceutically acceptable salt,
hydrate, or hydrated salt; or a polymorphic
crystal; or an optical isomer, racemate,
diastereomer, or
enantiomer thereof.