The relevance of cell kinetics for optimal scheduling of 1-beta-D-arabinofuranosyl cytosine and methotrexate in a slow growing acute myeloid leukemia (BNML).

1-beta-D-Arabinosyl cytosine and methotrexate were studied for their antitumor activity in acute myeloid leukemia of the BN rat (BNML), which is characterized by a slow growth rate due to the presence of a high proportion of nonproliferating cells. It was found that the two drugs showed the maximal cytotoxic action when given separately. The effect was highly dependent on the interval between the administration of each drug. The variation of the cell kinetic parameters produced by the recruitment into cycle of the resting population, as determined by labeling indices, correlates well with the antileukemic action of the drug combination.