Detection of minimal residual disease in Acute Myeloid Leukemia with t(8;21) translocation

by Christina Papadaki

Institution: Ludwig-Maximilians-Universitt
Year: 2017
Posted: 02/01/2018
Record ID: 2222127
Full text PDF: https://edoc.ub.uni-muenchen.de/20967/


Acute myeloid leukemia (AML) with t(8;21) rearrangement, constitutes about 5% of all AML cases and is characterized by the presence of RUNX1-RUNX1T1 fusion gene. Although this subtype, referred as CBF leukemia, belongs to the favorable cytogenetic risk group, 25% to 30% of the patients relapse. Detection of minimal residual disease (MRD) is of major importance since it evaluates the depth of the remission and therefore, risk adapted therapy based on early detection of relapse becomes feasible. RUNX1-RUNX1T1 fusion gene could be used for MRD detection using RQ-PCR. Within this work, a sensitive, specific and easy to perform, calibrator normalized relative quantification with external standards assay for RUNX1-RUNX1T1 transcript levels, was established and has consequently been integrated in the routine diagnostic work-up of RUNX1-RUNX1T1 positive patients. ABL1 was used as a reference gene and cDNA of the Kasumi-1 cell line as a calibrator. Relative quantification was performed by calculating the RUNX1-RUNX1T1/ ABL1 ratio, which was further normalized to the RUNX1-RUNX1T1/ABL1 expression ratio of Kasumi-1 calibrator. Maximum sensitivity of the assays for both target and reference gene, was higher than 10-4 (5x10-4). The sensitivity of 5x10-4 was also confirmed using cDNA dilutions from Kasumi-1 cell line as well as dilutions of patients cDNA. The specificity of the assay was determined when RUNX1-RUNX1T1 negative patients were tested; along with cDNA from negative cell lines and no amplification was observed. 184 samples from 39 patients, were quantified in order to assess the clinical usefulness of the assay. Transcript levels in 12 patients were measured on day 16 and were correlated to the clinical outcome. Moreover in 20 patients, comparison of the RUNX1-RUNX1T1 ratios at diagnosis and before consolidation revealed a 3 log10 decrease, which was also correlated to the disease outcome. 28% (11/39) of the patients in the study relapsed, consistent with previous studies.Very importantly, due to the good correlation of RUNX1-RUNX1T1 transcripts with the disease course, this assay will also be used to monitor MRD of t(8;21) positive patients within the recently launched AMLCG2014 study.Advisors/Committee Members: Spiekermann, Karsten (advisor).