[Antitumor activity of a new platinum complex (R)-(-)-2-aminomethylpyrrolidine (1,1-cyclobutane dicarboxylato) platinum (II) (DWA2114R) by its serial administration].

Antitumor activity of a newly synthesized platinum complex, DWA2114R, by the serial administration was examined and compared with that of cis-diammine-1,1-cyclobutane dicarboxylato platinum (II) (CBDCA). In mice transplanted s.c. with tumor, the serial i.p. administration resulted in the increases of both maximal tolerated dose (MTD) and growth inhibitory ratio (GIR) of DWA2114R than single administration. Such increases in MTD and GIR were also shown by CBDCA, but the degree of these increases, such as the ratio of MTD or GIR by the serial administration compared to that at the single administration, was higher in DWA2114R than CBDCA. GIR of DWA2114R by the serial administration was higher than that of CBDCA at the doses to induce the same toxicity which was estimated by body weight loss. In addition, in the experiment using ascites tumor-bearing mice, better antitumor activity of DWA2114R was shown by the elongation of survival time. These results indicate that the cumulative toxicity of DWA2114R is lower than that of CBDCA, which causes the therapeutic advantages of DWA2114R in the serial administration.