The present invention relates to novel piperidine derivatives having better cell growth inhibitory activities toward PANC-1 cancer cell cultures than FK866. Accordingly, the present invention relates to compounds of formula I, wherein Ar1 is aryl or heteroaryl, which are optionally substituted by one, two or three substituents selected from lower alkyl lower alkoxy formyl hydroxyl lower alkyl substituted by lower alkoxy or hydroxyl A is CnH2n, CnH2n-2 or CnH2n-4, wherein n=4,5,6,7 B is =N-CN, oxo (=O), thio (=S) D is NH, -CH=CH- Ar2 is aryl or heteroaryl which are optionally substituted by one, two or three halogen substituents wherein, if B is oxo (=O), Ar1 and Ar2 are not simultaneously phenyl and pyridine-3-yl B and D are not simultaneously =N-CN and -CH=CH-, or a pharmaceutically acceptable salt, a racemic mixture or its corresponding enantiomers and/or optical isomers. The compounds of formula I and their pharmaceutically usable addition salts possess valuable pharmacological properties. Specifically, it has been found that the compounds of the present invention, alone or in combination with other therapeutic active compounds, have an activity as chemotherapeutic agents against pancreatic cancers.
