Beschreibung:
<jats:title>Abstract</jats:title><jats:p>As a result of the excellent responses achieved in chronic phase chronic myeloid leukemia since the introduction of imatinib, sensitive techniques such as reverse transcriptase real‐time PCR are warranted to monitor patients receiving tyrosine kinase inhibitors (TKI). Our objective was to determine the value of molecular monitoring Ph‐positive leukemias under dasatinib treatment. We used real‐time PCR and <jats:italic>ABL1</jats:italic> kinase domain sequencing on sequential samples from 11 patients with Philadelphia‐positive leukemias who received dasatinib. We were able to detect pre‐existing mutations in the kinase domain of <jats:italic>BCR‐ABL1</jats:italic> in four patients, particularly in patients with high <jats:italic>BCR‐ABL1</jats:italic> transcript levels. Most mutations disappeared with dasatinib, however, in five patients a clone with T315I appeared during dasatinib treatment. We conclude that sensitive molecular monitoring with real‐time PCR for <jats:italic>BCR‐ABL1</jats:italic> transcripts and mutation screening of the <jats:italic>ABL1</jats:italic> kinase domain of patients with Philadelphia‐positive leukemias are valuable for patient management, however, mutation findings should be interpreted with caution, as mutant clones not always behave <jats:italic>in vivo</jats:italic> as predicted by <jats:italic>in vitro</jats:italic> assays.</jats:p>