Disclosed is a compound of formula (I) where the substituents are as disclosed in the description wherein, R1 is hydrogen, fluoro, cyano, trifluoromethyl or methoxy R2 is hydrogen, fluoro or trimethylfluoro R3 is hydrogen or chloro, provided that at least one of R2 and R3 is hydrogen R4 is chloro, fluoro, cyano, trifluoromethyl, difluoromethoxy, methoxy or trifluoromethoxy and the N-N heterocycle represents a substituted piperazine-1,4-diyl. Examples of the compounds of formula (I) are: N-(4-Fluorophenyl)-4-(4-(4-fluorophenyl)phthalazin-1-yl)-trans-2,5-dimethylpiperazine-1-carboxamide hydrochloride N-(4-Fluorophenyl)-4-(4-(4-fluorophenyl)phthalazin-1-yl)-2-(hydroxymethyl)piperazine-1- carboxamide hydrochloride and N-(4-Cyanophenyl)-2-methyl-4-(4-phenylphthalazin-1- yl)piperazine-1-carboxamide hydrochloride. The compounds are suitable for use in treating cancer such as brain cancer, basal cell carcinoma, esophagus cancer, gastric cancer, pancreatic cancer, biliary tract cancer, prostate cancer, breast cancer, small-cell lung cancer, non-small cell lung cancer, B-cell lymphoma, multiple myeloma, ovarian cancer, colorectal cancer, liver cancer, kidney cancer and melanoma. Also disclosed is a pharmaceutical compositions comprising compounds of formula (I).
