Prediction of sensitivity to 1-β-d-arabinofuranosylcytosine by the plateau level of its 5′-triphosphate in human lymphoblastic cell lines in vitro

Parameters for metabolism of 1-β-d-arabinofuranosylcytosine (ara-C) were examined to know whether the prediction of ara-C sensitivity is possible or not using 9 human lymphoblastic cell lines, 3 T cell lines and 6 B cell lines in vitro. Neither the capacity for synthesis, degradation, of 1-β-d-arabinofuranosylcytosine 5′-triphosphate (ara-CTP), generally lower in the T than B cell lines, nor deamination of ara-C, negligible in the B cell lines, could be correlated to the drug sensitivity. On the other hand, significant correlation was obtained between the sensitivity and the plateau level of ara-CTP. We consider that ara-C sensitivity could be predicted by measuring the plateau ara-CTP level before commencement of chemotherapy.