Heterocyclic compounds as protein kinase inhibitors

A compound having the structure of formula (I),

• a pharmaceutically acceptable salt thereof, a prodrug thereof or a hydrate thereof, wherein:
• A and B independently represent N or CR, with the proviso that both A and B are not N;
• R, R′ and R″ independently represent H, (C1-C6) alkyl, halogen, —CN, —NRaRb, —NRaCORb or —CONRaRb, with the proviso that R′ represents H, halogen or —NRaCORb when A is N and R″ represents H, halogen or —NRaCORb when B is N;
• R1 represents H, (C1-C3) alkyl or —COR4;
• R2 represents H, (C1-C3) alkyl, halo or —CN;
• R3 represents H, (C1-C3) alkyl, halo, —CN or —COR4;
• R4 represents optionally substituted phenyl, with the proviso that R1 represents —COR4 when A is N and R3 represents —COR4 when B is N;
• Ra and Rb independently represent H, (C1-C8) alkyl, (C3-C8) cycloalkyl or OR′″;
• Ra and Rb are taken together with the N atom to which they are attached to form 3-8 membered heterocyclyl, optionally containing additional heteroatom(s) selected from N, O or S, wherein heterocyclyl is optionally substituted;
• and
• R′″ represents H or (C1-C3) alkyl.