A comparison of the tumour concentrations obtainable with misonidazole and Ro 03-8799.

Both Ro 03-8799 and misonidazole were administered to six patients before tumour sampling. Using similar doses, tumour concentrations of Ro 03-8799 were approximately double those of misonidazole. Examination of the data with regard to the relative sensitising efficiencies of these two compounds gives us, as a conservative estimate, a factor of 1.6 in favour of Ro 03-8799. From these observations it is predicted that, when given with radiotherapy in a 25-fraction course Ro 03-8799, is likely to be at least five times more effective as a hypoxic cell sensitiser than misonidazole.