Dose response relationship of methotrexate in combination with cisplatin in murine bladder cancer

Methotrexate (MTX) has activity in transitional cell carcinoma (TCC) in man and some have suggested an advantage of high-dose methotrexate versus the standard dose in controlling tumor growth and prolonging survival. MBT-2, a poorly differentiated TCC induced by the carcinogen FANFT, is both grossly and histologically similar to human TCC and has been used as an animal model. One hundred twenty C3H/HE female mice were injected in the hind limb with 7.5 X 10(4) MBT-2 tumor cells. When palpable tumors developed in all animals, therapy was initiated. Animals were randomized into a control group and nine treatment groups as follows: cisplatin (DDP), MTX32 mg, MTX50 mg, MTX80 mg, DDP + MTX32, MTX50 + Leucovorin, MTX80 + Leucovorin, DDP + MTX50 + Leucovorin, DDP + MTX80 + Leucovorin. The combination of MTX50 mg with Leucovorin + DDP and DDP alone were the two most effective regimens in controlling tumor growth and prolonging survival. No statistically significant difference was observed between the group treated by high-dose MTX alone and those treated by low-dose MTX. No toxicity was observed even when high doses of MTX were used.