In vitro and in vivo cytotoxicity tests were carried out using the YTS-1 human bladder carcinoma cell line. The lethal effects of a 1-hour treatment with 5 anti-cancer agents (Cisplatin [CDDP], Cytosine arabinoside [ara-C], Adriamycin [ADM], Etoposide and Carboplatin [CBDCA]) on the YTS-1 cells grown as monolyer were examined quantitatively by the regrowth assay methods. In addition, the lethal effects of 3 anti-cancer agents (CDDP, ADM, ara-C) were also examined in vivo. Moreover the effects

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... simultaneous combinations of CDDP and ara-C, and ADM and ara-C were assessed in vitro and in vivo. In vitro studies showed that, of these single agents, ADM and ara-C were cytotoxic judging from the human maximal plasma concentraiton of drugs, whereas CDDP, VP-16 and CBDCA were not. Combinations of CDDP and ara-C, and ADM and ara-C showed more than additive effect. In vivo studies on YTS-1 tumors implanted to athymic nude mice (BALB/c) showed that ADM was the cytotoxic agent. Although CDDP alone or ara-C alone was not cytotoxic to YTS-1 tumors, combination of CDDP and ara-C showed antitumor activity. These results show that combination of CDDP and ara-C is synergistic. The most effective combination was observd to be ADM and ara-C, but severe loss of body weight was also observed.