Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia Is Separated into Two Subgroups Associated with Survival by BCR-ABL Fluorescence in situ Hybridization of Segmented Cell Nuclei: Report from a Single Institution

Management of children and adolescents with chronic myeloid leukemia in blast phase: International pediatric CML expert panel recommendations

Treatment of chronic myeloid leukemia has improved significantly with the introduction of tyrosine kinase inhibitors (TKIs), and treatment guidelines based on numerous clinical trials are available for chronic phase disease. However for CML in the blast phase (CML-BP), prognosis remains poor and treatment options are much more limited. The spectrum of treatment strategies for children and adolescents with CML-BP has largely evolved empirically and includes treatment principles derived from adult CML-BP and pediatric acute leukemia. Given this heterogeneity of treatment approaches, we formed an international panel of pediatric CML experts to develop recommendations for consistent therapy in children and adolescents with this high-risk disease based on the current literature and national standards. Recommendations include detailed information on initial diagnosis and treatment monitoring, differentiation from Philadelphia-positive acute leukemia, subtype-specific selection of induction therapy, and combination with tyrosine kinase inhibitors. Given that allogeneic hematopoietic stem cell transplantation currently remains the primary curative intervention for CML-BP, we also provide recommendations for the timing of transplantation, donor and graft selection, selection of a conditioning regimen and prophylaxis for graft-versus-host disease, post-transplant TKI therapy, and management of molecular relapse. Management according to the treatment recommendations presented here is intended to provide the basis for the design of future prospective clinical trials to improve outcomes for this challenging disease.

International Consensus Classification of Myeloid Neoplasms and Acute Leukemias: integrating morphologic, clinical, and genomic data

The classification of myeloid neoplasms and acute leukemias was last updated in 2016 within a collaboration between the World Health Organization (WHO), the Society for Hematopathology, and the European Association for Haematopathology. This collaboration was primarily based on input from a clinical advisory committees (CACs) composed of pathologists, hematologists, oncologists, geneticists, and bioinformaticians from around the world. The recent advances in our understanding of the biology of hematologic malignancies, the experience with the use of the 2016 WHO classification in clinical practice, and the results of clinical trials have indicated the need for further revising and updating the classification. As a continuation of this CAC-based process, the authors, a group with expertise in the clinical, pathologic, and genetic aspects of these disorders, developed the International Consensus Classification (ICC) of myeloid neoplasms and acute leukemias. Using a multiparameter approach, the main objective of the consensus process was the definition of real disease entities, including the introduction of new entities and refined criteria for existing diagnostic categories, based on accumulated data. The ICC is aimed at facilitating diagnosis and prognostication of these neoplasms, improving treatment of affected patients, and allowing the design of innovative clinical trials.

Multi-Lineage BCR-ABL Expression in Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia Is Associated With Improved Prognosis but No Specific Molecular Features

Background

Recently, various blood cell lineages expressing the BCR-ABL fusion gene in Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL) have been reported. However, the biological and clinical significance of these BCR-ABL lineages has not been established; therefore, we aimed to clarify the impacts of these different BCR-ABL-expressing lineages.

Patients

Multi-lineage BCR-ABL expression (multi-Ph) was defined as BCR-ABL expression outside of the B-lineage compartment, as determined by fluorescence in situ hybridization (FISH) in peripheral blood neutrophils and bone marrow clots, and flow cytometry-sorted polymerase chain reaction (PCR). We analyzed IKZF1 deletion patterns by PCR, examined gene expression profiles using RNA sequencing, and compared treatment outcomes across different BCR-ABL-expressing lineages.

Results

Among the 21 multi-Ph patients in our 59-patient cohort (36%), BCR-ABL expression was detected at the multipotential progenitor level. However, no IKZF1 deletion patterns or gene expression profiles were identified that were specific for multi-Ph. However, multi-Ph patients were found to have better survival rates than patients with uni-lineage BCR-ABL expression [event-free survival (EFS): 74 vs. 33%, P = 0.01; overall survival (OS): 79 vs. 44% at 4 years, P = 0.01]. In multivariate analyses, multi-Ph was identified as a good prognostic factor for both EFS and OS.

Conclusion

We confirmed that more than one-third of Ph+ALL patients could be classified as mutli-Ph. Although no specific molecular characteristics were identified for multi-Ph, this phenotype was associated with better treatment outcomes.

A Case of Childhood Blastic Phase Chronic Myeloid Leukemia With Minor BCR-ABL

Chronic myeloid leukemia (CML) is commonly associated with major BCR-ABL transcript. We present a child with blastic phase CML associated with minor BCR-ABL transcript without prior CML diagnosis. Diagnosis was achieved by fluorescence in situ hybridization of peripheral blood neutrophils, which identified 90% as BCR-ABL positive. The patient received chemotherapy with imatinib followed by dasatinib and underwent reduced-intensity hematopoietic allogeneic stem cell transplantation with prophylactic posttransplant dasatinib for 2 years and has remained in complete molecular remission. Our intensified treatment regimen was effective compared with previous studies on minor BCR-ABL CML describing inferior outcomes with tyrosine kinase inhibitor therapy.

Chronic myeloid leukemia presenting in lymphoblastic crisis, a differential diagnosis with Philadelphia-positive B-lymphoblastic leukemia

Rare patients with chronic myeloid leukemia (CML) can present initially in lymphoblastic crisis (LBC) mimicking Ph + B-lymphoblastic leukemia (B-ALL). We retrospectively reviewed 275 adults who diagnosed initially as Ph + B-ALL and identified 28 patients with at least one of three features supporting the diagnosis of CML-LBC: 1) a large discrepancy between the blast count and Ph + clone; 2) Ph + clone persistent when B-ALL in remission; 3) BCR/ABL1 fusion detected in segmented cells. BCR-ABL1 fusions were p210 in 25 patients and p190 in 3 patients. In comparison to patients with Ph + B-ALL, patients with CML-LBC were older; had higher leukocyte and absolute neutrophil counts; higher immature myeloid cells in peripheral blood; lower blast counts; and inferior outcomes. In addition, we prospectively analyzed 26 patients with Ph + B-lymphoblastic leukemia and identified 8 patients with features more consistent with CML-LBC. These findings highlight the importance of distinguishing CML-LBC from de novo Ph + B-ALL.

Genetic Testing in the Diagnosis and Biology of Acute Leukemia

OBJECTIVES

The 2017 Workshop of the Society for Hematopathology/European Association for Haematopathology examined the role of molecular genetics in the diagnosis and biology of acute leukemia.

METHODS

Acute leukemias were reviewed in two sessions: "Genetic Testing in Diagnosis of Acute Leukemias" (53 cases) and "Genetics Revealing the Biology of Acute Leukemias" (41 cases).

RESULTS

Cases included acute lymphoblastic leukemia, acute myeloid leukemia, and acute leukemia of ambiguous lineage. Many cases demonstrated genetic alterations of known diagnostic, prognostic, and/or therapeutic significance, while others exhibited alterations that illuminated disease biology. The workshop highlighted the complexity of acute leukemia diagnosis and follow-up, while illustrating advantages and pitfalls of molecular genetic testing.

CONCLUSIONS

Our understanding of the molecular genetics of acute leukemias continues to grow rapidly. Awareness of the potential complexity of genetic architecture and environment is critical and emphasizes the importance of integrating clinical information with morphologic, immunophenotypic, and molecular genetic evaluation.

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.

Low-dose decitabine enhances chidamide-induced apoptosis in adult acute lymphoblast leukemia, especially for p16-deleted patients through DNA damage

AIM

To investigate the combined action of decitabine (DAC) with chidamide (CS055) on acute lymphoblastic leukemia (ALL) cells.

MATERIALS & METHODS

ALL cell lines as well as primary cells from 17 ALL patients were subjected to different treatments and thereafter cell counting Kit-8 (CCK-8) assay, flow cytometry and western blot were employed to determine IC₅₀, apoptosis and checkpoint kinase 1 and γH2A.X expression.

RESULTS

Low-dose DAC combined with CS055 could effectively kill ALL cells by the reduction of cell viability and induction of apoptosis. This was also observed in primary cells from 17 ALL patients, especially for those with p16 gene deletion. Suppression of checkpoint kinase 1 phosphorylation and upregulation of γH2A.X expression was demonstrated to participate in DAC plus CS055-induced apoptosis.

CONCLUSION

Low-dose DAC could enhance chidamide-induced apoptosis in adult ALL, especially for patients with p16 gene deletion through DNA damage.