Session: 618. Acute Lymphoblastic Leukemia: Biology, Cytogenetics, and Molecular Markers in Diagnosis and Prognosis: Poster III
Hematology Disease Topics & Pathways:
Diseases, Leukemia, ALL, Technology and Procedures, cytogenetics, Lymphoid Malignancies, Clinically relevant, genetic profiling, molecular testing
Material and Methods: Since June 2015 we have therefore evaluated the feasibility of such a workflow in a prospective manner and screened so far 205 patients (i.e. 184 with B- and 21 with T-ALL, including 18 relapses with 14 diagnostic/relapse pairs) that were consecutively enrolled in the Austrian AIEOP-BFM 2009 treatment study. Cytogenetic preparations served as backup, since metaphase spreads were used for further FISH clarification of otherwise unresolvable complex rearrangements or ploidy patterns if deemed necessary. All identified gene fusions were subsequently validated with single or multiplex RT-PCR analyses.
Results: FISH screening was positive in 90% (184/205) of cases and provided already the most essential diagnostic clues. CNAs were present in all T-ALL and 97% (179/184) of B-ALL cases, including 13 with an IKZF1pluspattern and three with ERG deletions, which both will be used das stratifying markers in the upcoming treatment trial. Taken together, our screening strategy allowed the unambiguous classification of the vast majority of B-ALLs: 70 hyperdiploid, 3 hypodiploid, 35 ETV6-RUNX1, 6 KMT2A-rearranged, 8 TCF3-PBX1, 2 BCR-ABL1, 4 dic(9;20), 5 iAMP21, 8 IGH-rearranged, 6 P2RY8-CRLF2, 3 PAX5-rearranged, 3 ZNF384-rearranged, 2 ETV6-rearranged, 3 TKA fusion-positive and 10 so called "B-other" cases without any apparent specific abnormality. RNA-sequencing analyses of these ten cases revealed that seven of them harbored a DUX4 gene rearrangement.
Conclusions: Apart from its proven practical diagnostic value, our combined FISH/array approach has also several additional advantages, especially if one considers the amount of achievable information. Both procedures require only little amount of material and are highly standardized, reproducible and robust technologies. Moreover, arrays deliver DNA-sequence-based data, the coordinates of which can be efficiently stored, processed and analyzed. As such, they not only serve as a pure diagnostic tool but also as a valuable discovery platform.
Disclosures: No relevant conflicts of interest to declare.
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