Antibody-drug conjugate comprising anti-claudin-18.2 antibody, and therapeutic use thereof for cancer

An antibody-drug conjugate having a structure of following formula 1:

• wherein, Ab is an antibody unit,
• L is a linker unit,
• D is a drug unit,
• n is an integer of 1 to 4,
• the antibody unit is a conjugated anti-claudin18.2 antibody,
• the drug unit is linked to one or more of K246 and K248 of a Fc region of the antibody unit,
• the linker unit has a structure of following formula 2:
• wherein, b is an integer of 0 to 6,
• X′ is NH—, —C(O)—, or —NHC(O)—,
• B′ is a group formed by a click-chemistry reaction between click-chemistry functional groups,
• each of PM1 and PM2 is independently a PEG moiety, wherein the PEG moiety comprises 1 to 10 ethylene glycol units, wherein the ethylene glycol unit is —CH2OCH2—, —OCH2CH2— or —CH2CH2O—,
• 1* represents an attachment site with Ab,
• 2* represents an attachment site with D, and
• the drug unit is a Monomethyl auristatin E (MMAE).