Antibody-drug complex containing toll-like receptor 7/8 dual agonist compound

An antibody-drug conjugate of formula (I) or salt thereof:

• wherein
• Ab is an anti-CLDN6 antibody or an antigen-binding fragment thereof,
• X is S or NH,
• R1 is a lower alkyl or —CH2-isoxazoldiyl-CH3, with the caveat that if R1 is —CH2-isoxazoldiyl-CH3, then X is S,
• R2 is halogen or H,
• R3 is CH3 or H,
• R4 is a group of formula (a), (b), or (c):
• wherein
• ring A is a 4- to 6-membered cyclic amine comprising a plurality of C and one N,
• ring B is a 4- to 6-membered cyclic amine comprising a plurality of C, one N, and one G, with G being N or CH,
• RA is —CH2O—, —C(CH3)2O—, —O— or —CH2NH—, with the caveat that if RA is —O— or —CH2NH—, then X is S, R2 is halogen, or R3 is CH3,
• RB is a haloalkyl, CH2OH, C(CH3)2OH, OH, CH2NH2, or H, with the caveat that if RB is OH, CH2NH2, or H, then G is CH, X is S, R2 is halogen, or R3 is CH3,
• RC is a C3-6 cycloalkyl or a —CH2—C3-6 cycloalkyl,
• L is -lower alkylene-, —C(═O) lower alkylene-, —C(═O)NH lower alkylene-, —C(═O) lower alkylene-(OCH2CH2)m—NH—C(═O) lower alkylene-, —(CH2CH2O)m—C(═O) lower alkylene-, or —C(═O)-cyclohexandiyl-lower alkylene-,
• m is an integer in a range of from 1 to 10, and
• n is in a range of from 1 to 16, and
• wherein the antibody-drug conjugate of formula (I) is selected from the group consisting of
• an antibody-drug conjugate comprising Ab bound to 1-{3-[(3S)-4-[(4-{[2-amino-4-(pentylamino)-5H-pyrrolo[3,2-d]pyrimidin-5-yl]methyl}-3-methoxyphenyl)methyl]-3-(fluoromethyl)piperazin-1-yl]-3-oxopropyl}-1H-pyrrole-2,5-dione,
• an antibody-drug conjugate comprising Ab bound to {(2S)-1-[(4-{[2-amino-7-chloro-4-(pentylamino)-5H-pyrrolo[3,2-d]pyrimidin-5-yl]methyl}-3-methoxyphenyl)methyl]pyrrolidin-2-yl}methyl [2-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)ethyl]carbamate,
• an antibody-drug conjugate comprising Ab bound to N-[(4-{[2-amino-4-(pentylamino)-5H-pyrrolo[3,2-d]pyrimidin-5-yl]methyl}-3-methoxyphenyl)methyl]-N-cyclopropyl-3-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)propenamide, and
• an antibody-drug conjugate comprising Ab bound to 1-{3-[(3R)-4-[(4-{[2-amino-4-(pentylamino)-5H-pyrrolo[3,2-d]pyrimidin-5-yl]methyl}-3-methoxyphenyl)methyl]-3-(fluoromethyl)piperazin-1-yl]-3-oxopropyl}-1H-pyrrole-2,5-dione.