Divalent bet decomposition agent and targeting molecule-drug complex

Abstract

Provided are a divalent BET decomposition agent and a targeting molecule-drug complex including the divalent BET decomposition agent as a drug. The present invention uses, as a divalent BET decomposition agent, a compound represented by formula (I) or a pharmaceutically acceptable salt thereof (in the formula, R1 and R2 are identical or different from each other and each represent a hydrogen atom or lower alkyl, R3 represents lower alkyl, R4 represents a halogen, R5 represents a halogen, R6 represents a halogen or lower alkoxy, Y represents -O-CH2-CH2-, -CH2-CH2-CH2-, -CH=CH-CH2-, or -NH-C(=O)-CH2-, and ring A represents a group of (i), (ii), or (iii)).