Hypoxic cell sensitlzation by misonidazole in vivo and in vitro

The effect of misonidazole (Ro 07–0582, Roche Products Ltd., Welwyn Garden City, Herts.) as a radiosensitizer of hypoxic cells has been reported for several cell lines in vitro and for many tumour lines grown in vivo (Adams et al., 1976a). However, there have been no direct comparisons of the effects of this drug in vivo and in vitro because of a lack of data on the intra-tumour concentration of the drug. Recently Flockhart et al. (1977) have developed a method to measure the concentration of unchanged, misonidazole in tumours by gas-liquid chromatography. This article reports measurements of the ability of misonidazole to sensitize hypoxic cells in four different tumours to radiation as a function of its measured concentration in the tumours at the time of irradiation. These results are compared with those previously obtained for cells in culture.