Chronic Myeloid Leukemia Coverage from Every Angle

Sensitivity of Molecular Monitoring in TKI Stopping Trials in CML

By: Melissa E. Fryman, MS
Posted: Wednesday, May 1, 2019

Identification of patients with chronic myeloid leukemia (CML) for treatment-free remission may be optimized by more sensitive molecular monitoring. When discontinuation of tyrosine kinase inhibitors (TKIs) is being considered, the risk of sequelae must be weighed against the risk of relapse, hence the impetus to develop diagnostic assays as sensitive as possible. Birgit Spiess, PhD, of the University Hospital Mannheim, Heidelberg University, Germany, and colleagues reported their methodology establishing a new system to quantify BCR-ABL1 amplicons in PLOS One.

In this study, the peripheral blood mononuclear cell RNA analytes of 92 patients with CML in major molecular remission (or better) were compared with those of 128 patients with CML who had stopped TKI treatment (per the EURO-SKI stopping trial). Quantitative real-time polymerase chain reaction results for BCR-ABL1 obtained with both assays were compared using unpaired and paired analyses. The routinely used LightCycler software was run using ABL1 as a reference gene (LightCycler/ABL1), and the new TaqMan software was run using GUSB as a reference gene (TaqMan/GUSB).

The researchers found that TaqMan/GUSB was consistently more sensitive than LightCycler/ABL1. Of the 92 patients included in the analysis, 34 had significantly higher BCR-ABL1 counts with the new system, with 13 patients being reclassified from BCR-ABL1–negative to BCR-ABL1–positive. Of the 128 patients from the EURO-SKI stopping trial, 14 patients had significantly higher BCR-ABL1 with the new system; 8 patients relapsed, and 2 were reclassified as not meeting the criteria for TKI discontinuation.

“We consider both methods as comparable and interchangeable in terms of achievement of [major molecular remission] and of longitudinal evaluation of clinical courses,” the authors concluded. “We believe that the development of higher sensitive detection methods will positively impact on diagnostics and treatment of CML patients.”

Disclosure: The study authors’ disclosure information may be found at

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