Cell kinetic factors, single drugs and combination

This communication focuses on the problems that exist in the application of cell kinetic information in cancer chemotherapy. From selected historical work, the following conclusions can be drawn. 1) Theoretically optimal drug sequences may fail to show the expected effect. 2) Similar drug sequences cause different effects in different tumors, even when the tumors have similar proliferation characteristics. The unpredictability and the heterogeneity in response make the extrapolation to clinical cancer chemotherapy very difficult. Better prediction may be made from the integration of results from studies combining cell kinetic factors, cellular pharmacokinetics, and biochemistry of drug exposure.