Effect of treatment schedule on antitumor activity of glycolate-0,0'-diammineplatinum(II), a new platinum derivative: comparison with cis-diamminedichloroplatinum(II).

The effect of treatment schedule on the antitumor activity of a new platinum derivative, glycolate-0,0'-diammineplatinum (II) (254S) compared with cis- diamminedichloroplatinum (II) (CDDP) was investigated using ascites L1210 leukemia and solid Lewis lung carcinoma. The drugs were given i.p. by three treatments: as a single injection, as three injections at 4 day intervals and as 9 daily continuous injections. 254S produced a marked increase of lifespan in mice by all three treatment schedules (about 100% ILS), although the consecutive treatment of 254S needed more total doses against L1210 leukemia. The antitumor activity of 254S was, however, inferior to that of CDDP. Moreover, 254S did not show certain dependence on treatment schedule, while CDDP was rather dependent on treatment schedule. The single injection (day 1) of CDDP exhibited the most potent antitumor activity. On the other hand, although the single injection of CDDP showed more host toxicity than the other treatment schedules and the consecutive treatment needed more total doses, neither drug showed any definite schedule dependency against Lewis lung carcinoma. Moreover, the tumor growth inhibitory activity of 254S was almost the same as or slightly superior to that of CDDP. Both drugs produced about 70% (days 14-17) and 50% (day 20) tumor weight inhibitions against early and advanced Lewis lung carcinoma, respectively.