The present invention relates to the use of a sulfonamide compound of formula (I): wherein R1 is selected from the group consisting of H, CN, halogen, trifluoromethyl, methyl, ethyl, hydroxy, methoxy, ethoxy, morpholino, R2 is selected from H, phenyl, substituted phenyl, CN, —SO2R, wherein R is phenyl or morpholino, —NC(O)Me, —NC(O)Et, —CH2C(O)OMe, CH2C(O)OEt, R3 is selected from the group consisting of H, NO2, NH2, halogen, —COOMe, —COOEt, RC(O)N—, morpholino, R4 is selected from the group consisting of H, a branched or unbranched methyl, ethyl, propyl, butyl, pentyl, methoxy, ethoxy, propoxy, butoxy, a substituted or unsubstituted phenyl, alkinyl, Me2SO2—, COOR, wherein R is a branched or unbranched methyl, ethyl, propyl, butyl, pentyl, -MeOC(O)—, a substituted or unsubstituted five or sixmembered aromatic or non-aromatic heterocyclic system with one, two or three heteroatoms, a hetaryl system, a condensed benzoheterocyclic system, X is a linker comprising 2 or 3 atoms, selected from the group consisting of —NH—NH—, —NH—NH—CH2—, ethinyl, —NH—C(O)—CH2—, —NH—NH—SO2—, —C(O)—NH—CH2—, —NH—N═CH—, —NH—N═C(Me)-, a —NH—N═CH— motif being part of a heterocyclic system, preferably a substituted or unsubstituted pyrazole or pyridazine system, and pharmaceutically active salts thereof. Further, the invention relates to the use of these compounds as a medicament, especially for the treatment of cancer.