Effect of 1-methyl-5-sulfonamide-4-nitroimidazole and 1-methyl-5-bromide-4-nitroimidazole on the radiosensitivity of EMT6 tumor cells.

The compounds 1-methyl-5-sulfonamide-4-nitroimidazole and 1-methyl-5-bromide-4-nitroimidazole are extremely effective radiosensitizers of hypoxic cells in vitro. Preincubation of hypoxic cells with these and related drugs produces greater sensitization than is obtained with short incubations or is expected from the electron affinities of the compounds. The experiments reported here were undertaken to determine whether these agents were effective in sensitizing the naturally occurring hypoxic cells of solid tumors in mice. Neither of the 4-nitroimidazoles produced significant radiosensitization of the hypoxic cells of EMT6 mouse mammary tumors in vivo with any of the single- or multiple-injection regimens tested.