A compound of formula or a pharmaceutically acceptable salt thereof: wherein: R 1, R 2, R 3 and R 4 are each independently selected from: hydrogen, cyano, CF 3, halogen, an alkyl group optionally substituted with a heterocycle, an alkoxy group optionally substituted with a heterocycle, a solubilising group, a heterocycle, -CO-NRR', -SO 2 -NRR', -NRR', -NR-CO-R' and -NR-SO 2 R' group wherein R and R' are each independently hydrogen or alkyl group; W is pyrimidinyl, unsubstituted or substituted by one or more substituents selected from: cyano, CF 3, halogen, an alkyl group optionally substituted with a heterocycle, a cycloalkyl group, an alkoxy group optionally substituted with a heterocycle, an aryl group, a heteroaryl group, a heterocycloalkyl group, a solubilising group, -CO-NRR', -SO 2 -NRR', -NRR', -NR-CO-R' and -NR-SO 2 R' group, wherein R and R' are each independently hydrogen or alkyl group; the solubilising group is selected from: morpholinyl, piperidinyl, pyrrolidinyl, N-(C 1 -C 6)alkylpiperidinyl, N-(4-piperidinyl)piperidinyl, 4-(1-piperidinyl)piperidinyl, 1-pyrrolidinylpiperidinyl, 4-morpholinopiperidinyl, 4-(N-methyl-1-piperazinyl)piperidinyl, piperazinyl, N-(C 1 -C 6)alkylpiperazinyl, N-(C 3 -C 6)cycloalkylpiperazinyl, pyrrolidinyl, N-(C 1 -C 6)alkylpyrrolidinyl, diazepinyl, N-(C 1 -C 6)alkylazepinyl, homopiperazinyl, N-methyl homopiperazinyl, N-ethyl homopiperazinyl and imidazolyl; X is (CH 2)n wherein n is 0, 1 or 2; Y is (CH 2) m wherein m is 1, 2, 3 or 4; Z is (CH 2) p wherein p is 1 or 2. R 1, R 2, R 3 and R 4 are each independently selected from: hydrogen, cyano, CF 3, halogen, an alkyl group optionally substituted with a heterocycle, an alkoxy group optionally substituted with a heterocycle, a solubilising group, a heterocycle, -CO-NRR', -SO 2 -NRR', -NRR', -NR-CO-R' and -NR-SO 2 R' group hydrogen, cyano, CF 3, halogen, an alkyl group optionally substituted with a heterocycle, an alkoxy group optionally substituted with a heterocycle, a solubilising group, a heterocycle, -CO-NRR', -SO 2 -NRR', -NRR', -NR-CO-R' and -NR-SO 2 R' group wherein R and R' are each independently hydrogen or alkyl group; W is pyrimidinyl, unsubstituted or substituted by one or more substituents selected from: cyano, CF 3, halogen, an alkyl group optionally substituted with a heterocycle, a cycloalkyl group, an alkoxy group optionally substituted with a heterocycle, an aryl group, a heteroaryl group, a heterocycloalkyl group, a solubilising group, -CO-NRR', -SO 2 -NRR', -NRR', -NR-CO-R' and -NR-SO 2 R' group, cyano, CF 3, halogen, an alkyl group optionally substituted with a heterocycle, a cycloalkyl group, an alkoxy group optionally substituted with a heterocycle, an aryl group, a heteroaryl group, a heterocycloalkyl group, a solubilising group, -CO-NRR', -SO 2 -NRR', -NRR', -NR-CO-R' and -NR-SO 2 R' group, wherein R and R' are each independently hydrogen or alkyl group; the solubilising group is selected from: morpholinyl, piperidinyl, pyrrolidinyl, N-(C 1 -C 6)alkylpiperidinyl, N-(4-piperidinyl)piperidinyl, 4-(1-piperidinyl)piperidinyl, 1-pyrrolidinylpiperidinyl, 4-morpholinopiperidinyl, 4-(N-methyl-1-piperazinyl)piperidinyl, piperazinyl, N-(C 1 -C 6)alkylpiperazinyl, N-(C 3 -C 6)cycloalkylpiperazinyl, pyrrolidinyl, N-(C 1 -C 6)alkylpyrrolidinyl, diazepinyl, N-(C 1 -C 6)alkylazepinyl, homopiperazinyl, N-methyl homopiperazinyl, N-ethyl homopiperazinyl and imidazolyl; X is (CH 2)n wherein n is 0, 1 or 2; Y is (CH 2) m wherein m is 1, 2, 3 or 4; Z is (CH 2) p wherein p is 1 or 2.