Analytical Validation of a Highly Sensitive, Multiplexed Chronic Myeloid Leukemia Monitoring System Targeting BCR-ABL1 RNA
JOURNAL OF MOLECULAR DIAGNOSTICS
Authors: Brown, Justin T.; Beldorth, Ion J.; Laosinchai-Wolf, Walairat; Fahey, Marie E.; Jefferson, Ken L.; Ruskin, Adam K.; Roth, Jacquelyn J.; Cai, Li; Watt, Christopher D.; Press, Richard D.; Yang, Fei; Hedges, John B.; Andruss, Bernard F.
Abstract
This study describes the analytical performance of the QuantideX qPCR BCR-ABL IS Kit, the first Food and Drug Administration-cleared assay designed to monitor breakpoint cluster region-Abelson tyrosine-protein kinase 1 (BCR-ABL1) fusion transcripts isolated from peripheral blood specimens from patients with chronic myeloid leukemia. This multiplex real-time quantitative RT-PCR assay amplifies both e13a2 and e14a2 Major BCR-ABL1 transcripts and the reference target ABL1. The test results are provided in international scale (IS) values by incorporating armored RNA-based calibrators that have defined IS values tied directly to the World Health Organization BCR-ABL1 Primary Reference Materials, without the necessity of determining and maintaining conversion factors. For each batch run, the integrated interpretive software evaluates run and specimen quality control metrics (including a sufficient amount of ABL1 control transcripts to ensure a minimal limit of detection) and calculates both molecular response (MR) and %IS values for each specimen. The test has a limit of detection of MR4.7 (0.002%IS) and a linear range from MR0.3 (50%IS) to MR4.7 (0.002%IS) for both Major transcripts. Single-site and multisite precision studies demonstrated a maximum SD of 0.13 MR (30% CV within the assay range between MR0.7 and MR3.7). The performance of this BCR-ABL1 monitoring test meets all of the clinical guideline recommendations for sensitivity and IS reporting for the management of chronic myeloid leukemia patients.
Chronic myelomonocytic leukemia with ETV6-ABL1 rearrangement and SMC1A mutation
CANCER GENETICS
Authors: Cessna, Melissa H.; Paulraj, Prabakaran; Hilton, Benjamin; Sadre-Bazzaz, Kianoush; Szankasi, Philippe; Cluff, Alice; Patel, Jay L.; Hoda, Daanish; Toydemir, Reha M.
Abstract
Chronic myelomonocytic leukemia (CMML) is a rare malignant neoplasm of the blood-forming cells in bone marrow characterized by persistent monocytosis. Although most patients with CMML show clonal genetic aberrations, there is no known cytogenetic or molecular genetic finding that is specific to CMML. We report a patient who had a clinical and morphological presentation consistent with CMML. The genetic work-up showed an ETV6-ABL1 fusion consequent to a 9;12 translocation, and a missense mutation in SMC1A (c.1757G>A, p.Arg586Gln). The SMC1A mutations are recurrent, albeit rare, in myeloid malignancies, without an established clinical significance in CMML. ETV6-ABL1 fusion is a rare but recurrent genetic aberration found in various hematologic malignancies involving both the lymphoid and myeloid lineage, but to the best of our knowledge, CMML is an exceptionally rare presentation of ETV6-ABL1 rearranged neoplasm. ETV6-ABL1 fusion is often formed through complex rearrangements, and usually cryptic by routine G-banded chromosome analysis. The diseases associated with this rearrangement generally have an aggressive course, hence detecting or excluding this rearrangement during diagnostic work-up is critical for treatment planning. (C) 2019 Elsevier Inc. All rights reserved.