Improved therapeutic index of cisplatin analogue: B-85-0040 by circadian timing

1. B-85-0040 is a new cisplatin analogue with dose limiting myelosuppression. 2. The maximum tolerated dose ranges between 300 and 525 mg/kg for single i.p. bolus injection in mice. 3. Its toxicity is circadian-stage dependent with optimal tolerance between 16 and 17 hours after lights on. 4. B-85-0040 is active in L1210 leukemia. Anti-tumor activity seems to be unrelated to the circadian stage of treatment. Optimal drug timing can therefore increase its therapeutic index.