Schedule-dependent effectiveness of ADM and multiple cycles of DDP on a murine reticulum sarcoma

The therapeutic index of adriamycin (ADM) and cisplatin (DDP) combination versus repeated sequences of the more active drug (DDP) was investigated on a murine reticulum cell sarcoma of ovarian origin (M5) implanted i.m. in C57BL/6 mice. The antitumor efficacy of multiple cycles of DDP according to different regimens at a prefixed time (every 7 days) or at tumor regrowth was also evaluated. Our data demonstrate that the ADM-DDP combination did not improve the antitumoral efficacy of DDP as single agent, while repeated cycles of DDP led to a significant increase in the host life span. Differences in therapeutic effect were elicited by the two schedules: the regimen at a prefixed time showed a major effect on local tumor control, although the regimen at tumor regrowth was better tolerated.