Enhanced cytogenetic and antitumor effects by 9-nitrocamptothecin and antineoplastics

Enhanced sister chromatid exchange (SCE) frequency by either melphalan (Mel ) or epirubicin (Epir) was observed when human lymphocytes were exposed in vitro to 9-nitro-20(S)-camptothecin (9NC). A correlation was observed betwe en the magnitude of the SCE response and the depression of the cell prolife ration index. The antitumor activity of Mel and of 9NC was tested on leukem ia P-388-bearing mice. The two chemicals in combination enhance antitumor a ctivity in a synergistic manner. Therefore, the in vivo antitumor effect of Mel in conjunction with 9NC appears to correlate well with the in vitro sy nergistic effect on SCE induction caused by the combined Mel plus 9NC treat ment. (C) 2000 Wiley-Liss, Inc.