Advantages in combination chemotherapy using cisplatin and its analogues for human testicular tumor xenografts

The antitumor effects and toxicities of combination chemotherapies using cisplatin (CDDP) and its analogues were compared with those of single drug therapies. Congenitally athymic nude BALB/c (nu/nu) mice were used to estimate antitumor activities of these compounds against human testicular tumor (Ht-14) xenografts and hetero-BALB/c (nu/+) mice were used to evaluate the toxic effects of the drugs. Combination therapy with half dosages of CDDP and carboplatin (JM8) (CDDP: 2, JM8: 20 mg/kg/day for 5 days), or of CDDP and (glycolato-O,O')-diammineplatinum (II) (254S) (CDDP: 2,254S: 4 mg/kg/day for 5 days), resulted in significant tumor regression. The combination of CDDP and JM8 had the highest therapeutic efficacy while the CDDP and 254S combination had a lower antitumor potency. In addition, the toxicities of the combination therapies were lower than what was produced by the highest dosage of CDDP (4 mg/kg/day for 5 days). These results demonstrated that the antitumor activities of these combination chemotherapies were equal or superior to the activity of CDDP or an analogue alone, and that the toxicities produced by these combinations were more manageable than those produced by single drug therapies.