A compound of formula: wherein - R 1 represents a five-membered heteroaryl ring selected from pyrazole, thiazole, or triazole rings optionally substituted by one or two halogen atoms or by one or two methyl or trifluoromethyl groups - R 2 represents hydrogen atom - R 3 represents a bromine atom, a chlorine atom or a cyano group - R 4 represents independently: a) a five-membered heteroaryl group optionally substituted by one or more halogen atoms or by one or more groups C 1 -C 8 alkyl, cycloalkyl, C 1 -C 8 alkoxy, C 1 -C 8 alkylthio, amino, mono- or di-C 1 -C 8 alkylamino b) a group -N(R 5)(R 6) in which R 5 and R 6 represent independently: - a hydrogen atom - an alkyl or cycloalkyl group of 3 to 6 carbon atoms, linear or branched, optionally substituted by one or more halogen atoms or by one or more groups cycloalkyl, hydroxy, C 1 -C 8 alkoxy, amino, mono- or di-C 1 -C 8 alkylamino - or R 5 and R 6 form together with the nitrogen atom to that they are attached a saturated heterocyclic group of 4 to 6 members in which further heteroatom may be inserted, which is optionally substituted by one or more halogen atoms or by one or more C 1 -C 8 alkyl groups, hydroxy, C 1 -C 8 alkoxy, amino, mono- or di-C 1 -C 8 alkylamino, or c) a group -OR 7 or -SR 7, where R 7 represents independently: - an C 1 -C 8 alkyl or cycloalkyl group, linear or branched, optionally substituted by one or more halogen atoms or by one or more groups C 1 -C 8 alkyl, C 1 -C 8 alkoxy, amino, mono- or di-C 1 -C 8 alkylamino - a Phenyl ring optionally substituted with one or more halogen atoms or a pharmaceutically acceptable salt thereof - R 1 represents a five-membered heteroaryl ring selected from pyrazole, thiazole, or triazole rings optionally substituted by one or two halogen atoms or by one or two methyl or trifluoromethyl groups - R 2 represents hydrogen atom - R 3 represents a bromine atom, a chlorine atom or a cyano group - R 4 represents independently: a) a five-membered heteroaryl group optionally substituted by one or more halogen atoms or by one or more groups C 1 -C 8 alkyl, cycloalkyl, C 1 -C 8 alkoxy, C 1 -C 8 alkylthio, amino, mono- or di-C 1 -C 8 alkylamino b) a group -N(R 5)(R 6) in which R 5 and R 6 represent independently: a) a five-membered heteroaryl group optionally substituted by one or more halogen atoms or by one or more groups C 1 -C 8 alkyl, cycloalkyl, C 1 -C 8 alkoxy, C 1 -C 8 alkylthio, amino, mono- or di-C 1 -C 8 alkylamino b) a group -N(R 5)(R 6) in which R 5 and R 6 represent independently: - a hydrogen atom - an alkyl or cycloalkyl group of 3 to 6 carbon atoms, linear or branched, optionally substituted by one or more halogen atoms or by one or more groups cycloalkyl, hydroxy, C 1 -C 8 alkoxy, amino, mono- or di-C 1 -C 8 alkylamino - or R 5 and R 6 form together with the nitrogen atom to that they are attached a saturated heterocyclic group of 4 to 6 members in which further heteroatom may be inserted, which is optionally substituted by one or more halogen atoms or by one or more C 1 -C 8 alkyl groups, hydroxy, C 1 -C 8 alkoxy, amino, mono- or di-C 1 -C 8 alkylamino, or c) a group -OR 7 or -SR 7, where R 7 represents independently: - an C 1 -C 8 alkyl or cycloalkyl group, linear or branched, optionally substituted by one or more halogen atoms or by one or more groups C 1 -C 8 alkyl, C 1 -C 8 alkoxy, amino, mono- or di-C 1 -C 8 alkylamino - a Phenyl ring optionally substituted with one or more halogen atoms or a pharmaceutically acceptable salt thereof c) a group -OR 7 or -SR 7, where R 7 represents independently: - an C 1 -C 8 alkyl or cycloalkyl group, linear or branched, optionally substituted by one or more halogen atoms or by one or more groups C 1 -C 8 alkyl, C 1 -C 8 alkoxy, amino, mono- or di-C 1 -C 8 alkylamino - a Phenyl ring optionally substituted with one or more halogen atoms or a pharmaceutically acceptable salt thereof - an C 1 -C 8 alkyl or cycloalkyl group, linear or branched, optionally substituted by one or more halogen atoms or by one or more groups C 1 -C 8 alkyl, C 1 -C 8 alkoxy, amino, mono- or di-C 1 -C 8 alkylamino - a Phenyl ring optionally substituted with one or more halogen atoms or a pharmaceutically acceptable salt thereof