[Effect of N-ethylenemaleimide on the inhibitory activity of cytostatics]

The cytostatic effect of endoxan, Tiotef, bleomycin and other drugs was increased by addition of a thioloprovic compound of N-ethylenmaleimide (N-EM) to the cultures of cancer cells in doses not affecting the synthesis of nucleic acids in these cultures. The sensibilizing effect of N-EM against the antitumor drugs was due to blocking of SH-enzymes responsible of synthesis or reparation of DNA. Thus, a simultaneous effect of N-EM on the thiol cycle and synthesis of nucleic acids was synergistic for a number of antitumor drugs. It provided an increased effect of the cytostatics in doses having no activity under conditions of routine in vitro tests.