NOVEL INDOLOCARBAZOLE COMPOUND INDOLO[2,3-A]PYRROLO[3,4-C]CARBAZOLE-5,7(6H)-DIONE (NB-506) - ITS POTENT ANTITUMOR ACTIVITIES IN MICE

NB-506 ndolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione] is a new ant itumor indolocarbazole compound. The growths of murine M5076 and Ehrli ch solid tumors were inhibited 76 and 96%, respectivelv, by i.v. injec tion at doses of 300 mg/m(2). Furthermore, NB-506 caused regression of nodules of human PC-13 lung cancer and MKN-45 stomach cancer cells at i.v. doses of 90 mg/m(2). Human HCT 116 and LS 180 colon cancers also regressed with injections of NB-506. Repeated injections of NB-506 ha d a stronger antitumor effect than intermittent injections in mice,wit h MKN-45. The cumulative toxicity of NB-506 was low in terms of lethal ity in mice, i.e., the LD(50)s on single and 10 repeated i.v. injectio ns into CDF1 mice were 990 and 810 mg/m2/injection, respectively. In c onclusion, NB-506 is considered to be an interesting possible candidat e as an anti-cancer drug for treatment of solid tumors in humans.