[Effect of administration schedules on the antitumor activity of CPT-11, a camptothecin derivative].

Effect of administration schedules on the antitumor activity of CPT-11, a novel derivative of camptothecin, against mouse L 1210 leukemia and Meth A fibrosarcoma was investigated. At the same total dose, CPT-11 showed more significant antitumor activity by repeated administration. The most effective administration intervals were 5 days for L 1210 and 1 to 3 days for Meth A. CPT-11 showed a considerable antitumor activity by the repeated treatments for 2 or 3 times of continuous administration for 3 or 5 days.