This invention concerns a compound of formula a N-oxide, a pharmaceutically acceptable addition salt, a quaternary amine and a stereochemically isomeric form thereof, wherein R1 is hydrogen, hydroxy, cyano, amino, mono-or di(C1-4alkyl)amino, formyl, carboxyl, C1-6alkyl, hydroxyC1-6alkyl, polyhaloC1-6alkyl, C2-6alkenyl, C2-6alkynyl, C3-7cycloalkyl, C1-6alkyloxy, C1-6alkylcarbonyl, aminocarbonyl, —S(═O)m—NH2, mono-or di(C1-4alkyl)aminocarbonyl, C1-6alkyloxycarbonyl, C1-6alkylcarbonyloxy, aryl, arylC1-6alkyl or aryloxy; R2 is hydrogen; halo; mercapto; formyl; cyano; carboxy; azido; hydroxy; oxiranyl; amino; mono- or di(C1-4alkyl)amino; formylamino; R5R6N—C(═O)—; R7—N═C(R8)—; C1-6alkyl-S(═O)m; aryl-S(═O)m; optionally substituted C2-6alkenyl; optionally substituted C2-6alkynyl; C1-6alkyloxy; hydroxyC1-6alkyloxy; aminoC1-6alkyloxy; mono- or di(C1-4alkyl)amino-C1-6alkyloxy; C1-6alkylcarbonyl; arylcarbonyl; Het1carbonyl; C1-6alkyloxycarbonyl; C1-6alkylcarbonyloxy; aryl; aryloxy; arylC1-6alkyloxy; arylthio; arylC1-6alkylthio; mono- or di(aryl)amino; Het1; Het1oxy; Het1thio; Het1C1-6alkyloxy; Het1C1-6alkylthio; mono- or di(Het1)amino; C3-7cycloalkyl; C3-7cycloalkyloxy; C3-7cycloalkylthio; C1-6alkylthio; hydroxyC1-6alkylthio; aminoC1-6alkylthio; mono- or di(C1-4alkyl)aminoC1-6alkylthio; optionally substituted C1-6alkyl; R3 or R4 each independently represent optionally be substituted phenyl, pyridyl, pyrimidinyl, pyrazinyl or pyridazinyl; —X— is a bivalent radical selected from —NR14—, —NH—NH—, —N═N—, —O—, —C1-6alkanediyl-, —C(═O)—, —CHOH—, —S—, —S(═O)m—; aryl is optionally substituted phenyl; Het1, Het2 or Het3 represent an optionally substituted monocyclic or bicyclic heterocycle; their use as a medicine, their processes for preparation and pharmaceutical compositions comprising them.