In Vitro Evaluation of 1-β-D-Arabinofuranosylcytosine-β-2-Deoxythioguanosine Combination Chemotherapy

This study was designed to demonstrate the importance of sequence in the administration of 1-β-Darabinofuranosylcytosine (ara-C) and β-2-deoxythioguanosine in combination chemotherapy. The effects of various sequences of these drugs on the cloning ability of HeLa and Chinese hamster ovary cells were measured. The results indicate that the sequence in which ara-C was followed by β-2-deoxythioguanosine produced the maximum cell kill. The synergistic effect of this sequence was found to be due to the synchronizing effect of ara-C at very low doses. From a clinical point of view, these results suggest that the administration of ara-C in short-pulse infusions at a low dose to set up the tumor cells for therapy with β-2-deoxythioguanosine might be a better alternative to the lengthy infusions of ara-C prescribed for its own effect as an antitumor agent.