The application relates to novel sulfoximine substituted quinazoline derivatives of formula (I) wherein Ar, R1, R2 and R3 are as defined in the description and claims, and their use as MNK1 (MNK1a or MNK1b) and/or MNK2 (MNK2a or MNK2b) kinase inhibitors, pharmaceutical compositions containing the same, and methods of using the same as agents for treatment or amelioration of MNK1 (MNK1a or MNK1b) and/or MNK2 (MNK2a or MNK2b) mediated disorders.