Background: Increased cell-free DNA (cf-DNA) and the integrity of cf-DNA in plasma of patients with cancer has been described. We investigated the clinical utility of cf-DNA in the detection and monitoring of progression of leukemia.
Methods: Plasma samples from 60 patients with acute leukemia were analyzed in comparison to plasma from 30 healthy controls. Plasma DNA was determined by quantitative PCR (qPCR) by amplifying the β-actin gene (ACTB). The DNA integrity index was calculated as the ratio of qPCR results (ACTB384/106). Paired diagnostic/complete remission (CR)/relapse samples from eight of 60 patients were analyzed, and the minimum residual disease (MRD) situations were monitored.
Results: DNA concentrations (median: 8.80 ng/mL, p=0.004) and DNA integrity (median: 0.51, p<0.001) in cancer patients were significantly higher. Receiver operating characteristic (ROC) curve analysis showed that the area under the ROC curve of DNA and DNA integrity were 0.79 and 0.88, respectively. DNA integrity at CR had a distinct reduction and then an increase at relapse. DNA integrity in CR cases was higher than that observed in healthy controls.
Conclusions: Our preliminary data suggest that plasma DNA integrity is increased in acute leukemia and may be a potential biomarker for monitoring MRD. However, more work is needed.