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.