Disclosed is a compound of formula I wherein Ra is the same or different and each: (1) C1-6 alkyl, or (2) halogen atom, n1 is an integer selected from 0 to 4, Rb is the same or different and each: (1) C1-6 alkyl, or (2) halogen atom, n2 is an integer selected from 0 to 4, M1 is an integer selected from 0 to 3, m2 is an integer selected from 1 to 4, Xa=Xb is: (1) CH=CH, (2) N=CH, or (3) CH=N, X is: (1) nitrogen atom, or (2) C-Rd wherein Rd is hydrogen atom or halogen atom, RC is a group selected from the following (1) to (6): (1) hydrogen atom, (2) C'-6 alkyl optionally substituted by the same or different 1 to 5 substituents selected from the following Group A, (3) -C(=O)-Rc1,(4) -C(=O)-O-Rc2, (5) -C(=O)-NRC3Rc4 in which Rc1, Rc2, Rc3 and Rc4 are the same or different and each: (i) hydrogen atom, or (ii) C1-6 alkyl optionally substituted by the same or different 1 to 5 substituents selected from the following Group A, or (6) a group of formula 2 in which Ya is a group selected from the following (i) to (iii): (i) C1-6 alkylene, (ii) -C(=O)-, or (iii) -C(=O)-O-, Ring T is: (i) C6-10 aryl, (ii) C3-10 cycloalkyl, or (iii) saturated monoheterocyclyl wherein the saturated monoheterocyclyl comprises 1 to 4 heteroatoms selected from nitrogen atom, oxygen atom or sulfur atom as well as carbon atoms and the number of the constituent ring atoms is 3 to 7, Rc5 is the same or different and each: (i) cyano, or nitro, p is an integer selected from 0 to 4, group A is the group consisting of: (a) hydroxyl, (b) C1-6 alkoxy, (c) cyano,(d) C1-6 alkoxycarbonyl, (e) C1-6 alkylcarbonyloxy, and (f) C2-6 alkenyloxy, or a pharmaceutically acceptable salt thereof, or a solvate thereof. The compound is useful for treating organ transplant rejection, autoimmune diseases, allergic diseases and cancers.
