Evidence for recruitment and synchronization in leukemia and solid tumors

In malignant cell populations which are sensitive to drug therapy it does not seem necessary to potentiate treatment with perturbation of the proliferative characteristics. However, in some relatively drug-resistant populations significant advantages can be obtained by recruiting resting cells into the drug-sensitive cell cycle. Further studies of growth-regulatory mechanisms for malignant cell populations may help a great deal in designing better methods of recruiting the resting cells back into active cell division. Synchronization of the dividing cells in a specificially drug-sensitive phase of the cell cycle is another method of potentiating chemotherapeutic effectiveness in relatively drug-resistant cell populations. The biochemical changes induced by sequential drug administration may be equally important in sensitizing the malignant cell to subsequent drug administration.