[Chemosensitivity of human gastrointestinal and breast cancer xenografts in nude mice].

Experimental chemotherapies for 15 human cancers xenografted into nude mice were performed using 14 anticancer agents including 6 drugs in clinical use. Treatment with each single agent was performed for every cancer line using the maximum tolerated dose through continuous daily (antimetabolites) or intermittent (cytocidal agents) schedules. Effectiveness of each drug was evaluated by inhibition rate (IR) calculated from mean tumor weights of both treated and untreated groups. Response to a treatment was judged as effective when the IR was higher than 58%. Response rate of each drug was as follows; MMC was 67%, UFT 67%, CPA 47%, FT-207 40%, ACNU 33%, ADR 27%, SOAz 87%, 5'-DFUR 80%, MXT 20%, Leakadine 17%, M-83 17%, CAM 0% and GANU 0%. Generally, the experimental results for each drug on the xenografts was in good accordance with the known clinical effect of each drug on the same type of cancer. On the other hand, individual cancer xenografts showed considerable differences in chemosensitivity. Some tumors were sensitive to a majority of the drugs, whereas some were resistant to many of them. Each cancer line seemed to retain individuality in its spectrum of chemosensitivity irrespective of whether it originated from the same organ or whether it was of similar histologic type. This fact suggests the necessity of selecting drugs effective to the individual tumor when considering a patients chemotherapy regime.