Comparison of the antitumor activity of cisplatin, carboplatin, and iproplatin against established human testicular cancer cell lines in vivo and in vitro.

Cisplatin is a backbone of any combination chemotherapy currently in use for the treatment for nonseminomatous germ cell tumors. Recently new platinum analogs with lower toxicity have been developed. The antitumor activity of two analogs, carboplatin (JM8) and iproplatin (JM9) was compared to cisplatin in vitro and in vivo. The 3thymidine incorporation in three established human testicular cancer cell lines was significantly stronger inhibited by cisplatin than by JM8 or JM9. Cisplatin showed a significantly stronger antitumor activity against heterotransplanted human testicular cancer cell lines in the nude mouse than JM8 or JM9 when given at equitoxic doses. Although both analogs only moderately retarded the tumor growth, cisplatin produced a significant reduction of tumor volume in three of four cell lines. From these data it is concluded that the antitumor activity of cisplatin may be significantly superior to JM8 and JM9, and results of preclinical investigations should be awaited before replacement of cisplatin by JM8 or JM9 in the treatment of nonseminomatous germ cell tumors can be considered.