NITROGEN-CONTAINING BICYCLIC COMPOUND

PROBLEM TO BE SOLVED: To provide a compound effective for a therapeutic agent or a prophylactic agent of rejection reaction at organ transplantation, autoimmune disease or the like. SOLUTION: There is provided a compound represented by formula (I) or a salt thereof. [In the formula, X1is CR7or nitrogen; X2is CH or nitrogen; X3and X4are a group bonded to each other: -X3---X4- (wherein, the group is -CONR8-, -C(R9)=N- or the like); R1, R2, R3, R4and R7are each independently hydrogen, halogen, 1-6C alkyl or the like; R5is hydrogen or -NHR10; R6is hydrogen, 1-6C alkyl or R10'; R8is hydrogen, 1-6C alkyl which may be substituted, or saturated aliphatic heterocycle; R9is hydrogen, 1-6C alkyl, 1-6C alkoxy or the like; R10and R10'are each 3-8C cycloalkyl, aryl-1-6C alkyl or the like]. COPYRIGHT: (C)2011,JPO&INPIT