Definition

An antibody-drug conjugate (ADC) composed of a recombinant humanized monoclonal antibody against tumor-associated antigen (TAA) trophoblast cell surface protein 2 (trophoblast antigen 2; calcium signal transducer 2; TROP2; TROP-2; TACSTD2; GA733-1; M1S1) conjugated, via a 2,3-disubstituted long side chain hydrolysis-resistant linker, to the tubulysin B analog Tub196, with potential antineoplastic activity. Upon administration of the anti-TROP2 monoclonal antibody-Tub196 conjugate JS108, the anti-TROP2 antibody targets and binds to TROP2 expressed on tumor cells. Upon cellular uptake, the cytotoxic tubulysin B analog binds to tubulin, thereby affecting microtubule assembly and disassembly dynamics. This inhibits microtubule polymerization, which blocks cell division and results in G2/M phase arrest, tumor cell apoptosis and a decrease in proliferation of TROP2-expressing tumor cells. TROP2 is a transmembrane protein overexpressed in various tumors. Its expression is associated with enhanced tumor aggressiveness, metastasis, drug resistance, increased tumor cell survival and poor prognosis.