Cytarabine remains the backbone of
therapy in
acute myeloid leukemia (AML). The ability to assess intracellular
cytarabine triphosphate (
ara-CTP) levels in patients receiving
cytarabine represents a major goal in the prediction of treatment response. This study, conducted within a clinical setting, aimed to assess
ara-CTP levels in circulating peripheral blasts from non-M3 AML patients receiving
cytarabine at one of three dosing levels, using a novel biosensor assay. Results from the initial 72 hours post-commencement were correlated with day 28 remission status, with feasibility parameters concurrently assessed. Intracellular
ara-CTP was detectable in ex vivo blasts post-treatment for standard-dose (SD) and high-dose (HD) patients (p < 0.05), and quantification revealed a 27-fold increase in intracellular steady-state concentration between the two dosing levels. For low-dose
cytarabine, high rates of
patient discharge and low intracellular concentrations limited analysis; however, assessment of intracellular
ara-CTP concentration was achievable in a dwindling population of blasts for SD and HD treatment cohorts, with 4 hours post-treatment commencement potentially being most predictive of clinical response (r = -0.912, p = 0.0113). Concurrent assessment of peripheral
leukemia-associated immunophenotype (LAIP)-positive cells revealed a decline in burden (0-72 hours), which correlated with remission status (p < 0.05). Unexpectedly high rates of night sampling led to challenges associated with sampling rates, but did not have an impact on patient compliance. Additional training of night staff improved feasibility substantially. Multiple peripheral sampling during the initial 72 hours of treatment is feasible in newly diagnosed patients, and
ara-CTP is detectable over the initial 24 hours, facilitating prediction of chemosensitivity of leukemic blasts to
cytarabine.