BCR/ABL rearrangement with b3a3 fusion transcript in a case of childhood acute lymphoblastic leukemia

Three atypical BCR/ABL transcripts detected simultaneously in a Philadelphia-positive acute lymphoblastic leukemia patient showing resistance to tyrosine kinase inhibitors

The Philadelphia (Ph) chromosome with a BCR/ABL fusion gene is a characteristic feature of chronic myeloid leukemia (CML) and partial acute lymphoblastic leukemia (ALL) patients, with different breakpoints of the BCR and ABL genes. Here, we report the case of a Ph-positive ALL patient with poor prognosis in whom simultaneous different BCR/ABL transcripts named e1a3, e1a4, and e1a5 were detected by RNA-seq analysis but not traditional RT-PCR. To our knowledge, this is the first report to describe coexistence of different atypical BCR-ABL transcripts in the same patient and that traditional TKI therapy may not overcome the poor prognosis. This finding will bring new challenges in diagnosis and monitoring for minimal residual disease.

The bioengineered HALOA complex induces anoikis in chronic myeloid leukemia cells by targeting the BCR-ABL/Notch/Ikaros/Redox/Inflammation axis

Blast crisis (BC) is an outcome that arises during the treatment process of chronic myeloid leukemia (CML), which is possibly attained by the dysregulation of the Notch and Ikaros signaling pathways, BCR-ABL translocation, redox, and inflammatory factors. This study demonstrated that biotherapeutic agents target aberrant molecular axis in CML-BC cells. The HALOA complex was synthesized by simple mixing of apo α-lactalbumin with oleic acid, which manages to inhibit BCR-ABL (b3a2 in K562 cells) translocation. It elevates the production of reactive oxygen species (ROS), reactive nitrogen species (RNS), and protein carbonyl, which induces DNA fragmentation in K562 cells but not in NIH cells. The complex manages to reduce the toxicity surrounding apoptotic cells by enhancing the production of superoxide dismutase (SOD) and the total antioxidant level. The HALOA complex increases leptin to maintain normoxic conditions, ultimately preventing angiogenesis. This complex downregulates the expression of IL-8 and MMP-9 and elevates the expression levels of Notch 4, Ikaros, and integrin alpha-D/CD-11d (tumor-suppressive), which conjointly prevents inflammation, metastasis, and epithelial-mesenchymal transition (EMT) in CML cells. Meanwhile, the complex downregulates Notch 1 and 2 (oncogenic), consequently inducing anoikis in CML cells. Overall, the HALOA complex shows credibility by targeting the combined molecular factors responsible for the pathogenesis of the disease and will also help to overcome MDR conditions in leukemia.

A variant e13a3 BCR-ABL1 fusion transcript in refractory adult B-cell acute lymphoblastic leukemia achieving complete remission with CAR-Tcell therapy

Acute lymphoblastic leukemia (ALL) cases with e13a3 fusion transcripts are extremely rare. We report a 24-year-old male with Ph-positive (Ph+) ALL with an aberrant e13a3 fusion transcript treated with CD19-specific chimeric antigen receptor T-cell (CAR-T) therapy. He developed refractory disease post-chemotherapy induction, andreceived allogeneic hematopoietic stem cell transplantation (allo-HSCT) after salvage with imatinib in combination with chemotherapy regimen. Unfortunately, the patient relapsed after +90 days post-transplant. He was consented to CAR-T therapy trial and achieved complete remission, highlighting the efficacy of CAR-T treatment in relapsed-refractory B-ALL irrespective of the underlying genetic drivers in leukemia cells .

New rapid method to detect BCR-ABL fusion genes with multiplex RT-qPCR in one-tube at a time

Fast identification of BCR-ABL fusion genes is critical for precise diagnosis, risk stratification and therapy scheme selection in leukemia. More convenient methods are needed for quickly detection of the BCR-ABL fusion genes. Multiplex fluorescent reverse transcription quantitative real-time PCR (Multiplex RT-qPCR) methods are developed for detection of the at least 14 subtypes of BCR-ABL fusion genes in one tube at a time by using patients' bone marrow samples. The new Multiplex RT-qPCR method could quickly detect BCR-ABL fusion genes with sensitivity up to 10-10⁶ copies. It can detect the fusion genes in patients' bone marrow samples containing any subtypes of the major bcr (M-bcr) e13a2, e14a2, e13a3 and e14a3, the minor bcr (m-bcr) e1a2 and e1a3, the micro bcr (μ-bcr) e19a2 and e19a3, and the nano bcr (n-bcr) e6a2 and e6a3. The specificity is comparable to the FISH methods. The cutoff for clinical diagnosis of BCR-ABL(+) is also determined by testing in clinical chronic myeloid leukemia samples. This is a new fast method with high sensitivity and specificity for clinical detection of BCR-ABL fusion genes. It will benefit the precise diagnosis, targeted therapy and minimal residual disease (MRD) monitoring in leukemia.

A rare e14a3 BCR/ABL fusion transcript in acute lymphoblastic leukemia patient treated with CAR-modified T-cell therapy

E14a3 breakpoint cluster region (BCR)/ABL proto-oncogene 1, non-receptor tyrosine kinase (ABL) fusion transcript is rare in Philadelphia chromosome positive disease, particularly in acute lymphoblastic leukemia (ALL). Recently an e14a3 fusion transcript was detected by multiple laboratory examinations, and the patient was suffering from ALL. Except for the BCR/ABL fusion gene, in the present study the patient additionally had an IKAROS family zinc finger 1 deletion which, has been confirmed as a significant adverse prognosis factor. Following 2 rounds of chemotherapy, the patient presented cytological remission; however, the patient then relapsed 2 months later. They then received chimeric antigen receptor modified (CAR-modified) T-cell therapy and achieved complete remission. CAR-modified T-cell therapy is a powerful novel therapy which, exhibited great potential for treating refractory ALL, regardless of the existence and form of the BCR/ABL fusion transcript.

A novel BCR-ABL1 fusion gene identified by next-generation sequencing in chronic myeloid leukemia

BACKGROUND

BCR-ABL1 fusion proteins contain constitutively active tyrosine kinases that are potential candidates for targeted therapy with tyrosine kinase inhibitors such as imatinib in chronic myeloid leukemia (CML). However, uncharacterized BCR-ABL1 fusion genes can be missed by quantitative RT-PCR (qRT-PCR)-based routine screening methods, causing adverse effect on drug selection and treatment outcome.

CASE PRESENTATION

In this study, we demonstrated that the next-generation sequencing (NGS) can be employed to overcome this obstacle. Through NGS, we identified a novel BCR-ABL1 fusion gene with breakpoints in the BCR intron 14 and the ABL1 intron 2, respectively, in a rare case of CML. Its mRNA with an e14a3 junction was then detected using customized RT-PCR followed by Sanger sequencing. Subsequently, the patient received targeted medicine imatinib initially at 400 mg/day, and later 300 mg/day due to intolerance reactions. With this personalized treatment, the patient's condition was significantly improved. Interestingly, this novel fusion gene encodes a fusion protein containing a compromised SH3 domain, which is usually intact in the majority of CML cases, suggesting that dysfunctional SH3 domain may be associated with altered drug response and unique clinicopathological manifestations observed in this patient.

CONCLUSION

We identified a novel BCR-ABL1 fusion gene using NGS in a rare case of CML while routine laboratory procedures were challenged, demonstrating the power of NGS as a diagnostic tool for detecting novel genetic mutations. Moreover, our new finding regarding the novel fusion variant will provide useful insights to improve the spectrum of the genomic abnormalities recognizable by routine molecular screening.

Chronic myeloid leukemia with e14a3 BCR-ABL transcript: analysis of characteristics and prognostic significance

Chronic myeloid leukemia (CML) is characterized by Philadelphia chromosome (Ph) and BCR-ABL fusion genes. This study retrospectively analyzed 2381 CML patients with Ph chromosome confirmed by cytogenetics, Fluorescence in situ hybridization (FISH) or real-time quantitative polymerase chain reaction (Q-PCR). Among them, five CML patients without e13a2, e14a2 or e1a2 transcripts detected by Q-PCR were identified. DNA sequencing confirmed the fusion of BCR exon 14 and ABL exon 3. Case 1 reponded poorly to imatinib and achieved complete cytogenetic response (CCyR) after converting from imatinib to dasatinib. BCR-ABL transcripts were undetectable in cases after 2, 3 and 4 treated with imatinib after 6, 6 and 3 months, respectively, and in one patient who had undergone allogeneic hematopoietic stem cell transplantation after 4 months. Q-PCR may miss the detection of rare cases that are not covered by the primers used in Q-PCR, unless the proper primers are used.

A novel dic (17;18) (p13.1;q11.2) with loss of TP53 and BCR/ABL rearrangement in an Imatinib resistant chronic myeloid leukemia

Background

The so-called Philadelphia (Ph) chromosome is present in more than 90% of chronic myeloid leukemia (CML) cases. It results in juxtaposition of the 5′ part of the BCR gene on chromosome 22 to the 3′ part of the ABL gene on chromosome 9. Since the majority of CML cases are currently treated with Imatinib, variant rearrangements in general have no specific prognostic significance, although the mechanisms involved in resistance to therapy have yet to be investigated. The T315I mutation within the abl-gene is the most frequent one associated with resistance to tyrosine kinase inhibitors.

Results

This study evaluated a Ph chromosome positive CML case resistant to imatinib mesylate. A dic(17;18), loss of TP53 gene, co-expression of b2a2 and b3a2 fusions transcript and a T315I mutation were found.

Conclusions

We reported here a novel case of a Ph chromosome positive CML with a secondary abnormality [dic(17;18)], resulting to Glivec resistance but good response to nilotinib. The dic(17;18) might be a marker for poor prognosis in CML. Our finding indicated for an aggressive progression of the disease. The patient died under the treatment due to unknown reasons.