Assessment of individual molecular response in chronic myeloid leukemia patients with atypical BCR-ABL1 fusion transcripts: recommendations by the EUTOS cooperative network.
Approximately 1-2% of chronic myeloid leukemia (CML) patients harbor atypical BCR-ABL1 transcripts that cannot be monitored by real-time quantitative PCR (RT-qPCR) using standard methodologies. Within the European Treatment and Outcome Study (EUTOS) for CML we established and validated robust RT-qPCR methods for these patients.
BCR-ABL1 transcripts were amplified and sequenced to characterize the underlying fusion. Residual disease monitoring was carried out by RT-qPCR with specific primers and probes using serial dilutions of appropriate BCR-ABL1 and GUSB plasmid DNA calibrators. Results were expressed as log reduction of the BCR-ABL1/GUSB ratio relative to the patient-specific baseline value and evaluated as an individual molecular response (IMR).
In total, 330 blood samples (2-34 per patient, median 8) from 33 CML patients (19 male, median age 62 years) were analyzed. Patients expressed seven different atypical BCR-ABL1 transcripts (e1a2, n = 6; e6a2, n = 1; e8a2, n = 2; e13a3, n = 4; e14a3, n = 6; e13a3/e14a3, n = 2; e19a2, n = 12). Most patients (61%) responded well to TKI therapy and achieved an IMR of at least one log reduction 3 months after diagnosis. Four patients relapsed with a significant increase of BCR-ABL1/GUSB ratios.
Characterization of atypical BCR-ABL1 transcripts is essential for adequate patient monitoring and to avoid false-negative results. The results cannot be expressed on the International Scale (IS) and thus the common molecular milestones and guidelines for treatment are difficult to apply. We, therefore, suggest reporting IMR levels in these cases as a time-dependent log reduction of BCR-ABL1 transcript levels compared to baseline prior to therapy.
Publication Date: 2021-03-08
Journal: Journal of cancer research and clinical oncology
Clinicopathological characteristics of de novo and secondary myeloid sarcoma: A monocentric retrospective study.
Diagnosing myeloid sarcoma remains challenging, and we aimed to provide clinicopathological features to facilitate diagnosis.
Clinicopathological data from 41 patients with de novo and 31 with secondary myeloid sarcoma were reviewed.
Most de novo cases presented with isolated myeloid sarcoma (n = 19) or myeloid sarcoma with concurrent acute myeloid leukemia (n = 15). Most secondary cases presented after acute myeloid leukemia (n = 11), myeloproliferative neoplasm (n = 9), or myelodysplastic syndrome (n = 8). Most frequent localizations were skin and lymph nodes. Immunohistochemistry showed immature and/or aberrant antigenic expression in 29% of de novo and 39% of secondary cases. Most genetic abnormalities were RUNX1-RUNX1T1 (n = 4), CBFB-MYH11 (n = 2), KMT2A-MLLT3 (n = 2), and JAK2 V617F (n = 2) mutations in de novo myeloid sarcoma, and BCR-ABL1 (n = 5) and KMT2A rearrangements (n = 2) in secondary cases. A complex karyotype was seen in 17% of de novo and 39% of secondary cases. Most prevalent treatment was induction chemotherapy followed by consolidation chemotherapy (n = 10) or allogeneic stem cell transplantation (n = 9) for de novo and radiotherapy (n = 11) for secondary cases.
De novo myeloid sarcoma mostly presented isolated. Lesions were often localized at skin and lymph nodes. Genetic aberrations frequently involved core-binding factor rearrangements in de novo cases and a complex karyotype in secondary cases.
Publication Date: 2018-03-14
Journal: European journal of haematology
Application of tri-colour, dual fusion fluorescence in situ hybridization (FISH) system for the characterization of BCR-ABL1 fusion in chronic myelogenous leukaemia (CML) and residual disease monitoring.
We studied the application of the BCR-ABL1 + 9q34 tri-colour dual fusion fluorescence in situ hybridization (FISH) system in the characterization of fusion signal pattern and the monitoring of residual disease in chronic myelogenous leukaemia (CML). The signal constellation on metaphases with the tri-colour dual fusion system was defined. The knowledge of various signal patterns obtained from the different genetic rearrangements was further applied to the analysis of hybridization signals on interphase nuclei.
BCR-ABL1 dual colour, dual fusion FISH (D-FISH) was performed on diagnostic samples of 22 CML patients. The tri-colour FISH system was performed on cases that showed aberrant signal patterns other than the classical 1 green (G) 1 orange (O) 2 fusions (F). Using the aqua band-pass filter, random signal overlap in interphase nuclei would be indicated by the presence of an aqua signal (ASS1), while genuine fusion was represented by the absence of the ASS1 signal.
Using the D-FISH system, the signal patterns could be categorized into 4 groups: group 1 (n = 17) showed the classical 1G1O2F; group 2 (n = 2) showed 2G1O1F indicating ABL1 deletion; group 3 (n = 1) showed 1G2O1F indicating BCR deletion; group 4 (n = 2) with 1G1O1F indicating reciprocal ABL1-BCR deletion. The tri-colour dual fusion system correlated with the D-FISH system for cases with der(9) deletion. The added aqua-labelled ASS1 probe was useful in differentiating random signal overlap from genuine BCR-ABL1 fusion in the interphase cells (group 4).
Although the D-FISH probe was valuable in establishing the different patterns of aberrant signals and monitoring patients with the classic 2-fusion signals in CML, the tri-colour dual fusion probe should be used for patients with der(9) deletion to monitor response to treatment.
Publication Date: 2009-07-09
Journal: BMC blood disorders