Semustine orally once every 28 days at a dose of 150 mg/m2/day.

Cell lines BE and HT (HT-29), were used for activity evaluation. BE and HT cell cultures were treated with MMeCCNU (Semustine) 50, 100, or 200 mkM. For cell culture experiments, stock drug solutions were prepared immediately before use at a concentration of 12.38 mg/ml (0.05 M) in 95% ethanol. Appropriate dilutions of the stock solution were made so that 20 mkI of drug solution were added to cultures in all experiments. Addition of 20 mkl 95% ethanol had no effect on cell growth or DNA integrity in control cells. The experiments show that line BE is sensitive to MeCCNU treatment in tissue culture, which corresponds with its response in vivo. There is a differential response to 100 mkM MeCCNU between lines BE and HT. At this dose approximately 50% of the cells in the BE cultures were lost from the plate with remaining cells showing little or no proliferation capacity, while line HT showed only a slight initial inhibition of growth with little or no cell loss