Molecular characterization and clinical outcome of B-cell precursor acute lymphoblastic leukemia with IG-MYC rearrangement

How I diagnose high-grade B-cell lymphoma

OBJECTIVES

High-grade B-cell lymphoma (HGBL), introduced in the 2016 World Health Organization (WHO) revised fourth edition classification, included cases defined by MYC and BCL2 and/or BCL6 rearrangements or by high-grade morphology. Diagnostic criteria and nomenclature for these lymphomas were refined in the 2022 WHO fifth edition (WHO-5) classification and International Consensus Classification (ICC). This review describes our approach to the diagnosis of HGBL.

METHODS

Two cases are presented illustrating how we diagnose HGBL, including 1 case harboring MYC and BCL6 rearrangements and a second showing TdT expression in an HGBL with MYC and BCL2 rearrangements. The ways in which these cases are distinguished from other lymphomas with high-grade features and the appropriate nomenclature using WHO-5 and ICC classifications are emphasized.

RESULTS

An HGBL diagnosis requires integration of morphology, immunophenotype, and genetics and exclusion of other lymphomas with high-grade morphology, including Burkitt lymphoma, B-lymphoblastic leukemia/lymphoma (B-LBL/ALL), and blastoid mantle cell lymphoma. A diagnosis of HGBL/large B-cell lymphoma with 11q aberration should also be considered in certain patient populations.

CONCLUSIONS

High-grade B-cell lymphomas are subclassified based on morphologic and genetic features. There are differences in the nomenclature and definition of these lymphomas in the WHO-5 and ICC classifications. Distinguishing HGBLs from other mature B-cell lymphomas and B-LBL/ALL is critical so that patients receive appropriate treatment.

The t(18;22)/IGL::BCL2 translocation defines a unique CLL subtype: association with early treatment initiation

The most prevalent BCL2 fusion in B-cell lymphoma involves the IGH gene, attributable to the t(14;18)(q32;q21) translocation; this chromosomal abnormality is predominantly observed in follicular lymphoma (FL) and serves as one of its diagnostic hallmarks. In contrast, the fusion of BCL2 with IGL via the t(18;22)(q21;q11) translocation occurs less frequently. To investigate the clinicopathological characteristics associated with t(18;22)/IGL::BCL2, we conducted an analysis of five cases of B-cell lymphoma exhibiting the t(18;22) translocation. These patients underwent comprehensive diagnostic assessments, including pathological examination, flow cytometry, karyotyping, fluorescence in situ hybridization (FISH) testing, and genome-wide mutation analysis. Simultaneously, we conducted a literature review. All five patients in the study were male and diagnosed with chronic lymphocytic leukemia (CLL). Two patients exhibited an isolated t(18;22) chromosomal abnormality, while the remaining three presented with an additional +12 abnormality. Genetic rearrangements involving BCL2 and IGL were observed in all patients. Immunophenotypic analysis revealed no significant differences between classical CLL and cases with the t(18;22)/IGL::BCL2 translocation. Genetic testing conducted on three patients confirmed the presence of IGHV mutations. Of the three patients for whom treatment information was available, one demonstrated treatment indications at the initial diagnosis, one demonstrated treatment indications 14 months later, both of them did not respond to the Bruton's tyrosine kinase (BTK) inhibitor, and another one did not meet criteria for treatment. A comprehensive literature review identified 51 cases of the t(18;22)(q21;q11) translocation, primarily associated with CLL diagnoses. Detailed clinical trajectories were available for seven patients, among whom four required treatments at initial diagnosis, and two exhibited resistance to BTK inhibitors. Based on our case series and literature review, these cases appeared to have shorter time to first treatment (TTFT); however, more studies are needed. The t(18;22) chromosomal translocation, resulting in IGL::BCL2 fusion, is an infrequent occurrence predominantly observed in cases of CLL. This genetic anomaly frequently coexists with trisomy 12. Preliminary data suggest that these cases may have a shorter TTFT, though larger cohorts are needed for validation.

A case series of B-Lymphoblastic lymphoma with C-MYC rearrangement in children: diagnostic and therapeutic challenges

C-MYC rearrangement has been listed as a new subcategory of B-cell acute lymphoblastic leukemia (B-ALL) in the latest International Consensus Classification (ICC), but B-cell lymphoblastic lymphoma (B-LBL) with C-MYC rearrangement is extremely rare and therefore is a novel finding worth reporting. In this study, we described a small number of pediatric cases of B-LBL with C-MYC rearrangement, which overlapped features of B-LBL and Burkitt lymphoma (BL), including highly aggressive clinical presentation, lymphoblasts with precursor B-cell phenotype and C-MYC rearrangement; the combination treatment of the mature B-NHL protocol and ALL-type protocol may be appropriate for this rare entity, and more studies are required to identify an adequate therapeutic strategy.

Genetic subtypes of B-cell acute lymphoblastic leukemia in adults

ABSTRACT

B-cell acute lymphoblastic leukemia (B-ALL) is a rare malignancy in adults, with outcomes remaining poor, especially compared with children. Over the past 2 decades, extensive whole-genome studies have identified numerous genetic alterations driving leukemia, leading to the recognition of >20 distinct subtypes that are closely associated with treatment response and prognosis. In pediatric B-ALL, large correlation studies have made genetic classification a central component of risk-adapted treatment strategies. Notably, genetic subtypes are unevenly distributed according to age, and the spectrum of genetic alterations and their prognostic relevance in adult B-ALL have been less extensively studied, with treatment primarily based on the presence or absence of BCR::ABL1 fusion. This review provides an overview of genetic subtypes in adult B-ALL, including recent biological and clinical insights in well-established subtypes as well as data on newly recognized subtypes. Their relevance for risk classification, disease monitoring, and therapeutic management, including in the context of B-cell-directed therapies, is discussed. This review advocates for continuing efforts to further improve our understanding of the biology of adult B-ALL to establish the foundation of future precision medicine in B-ALL.

MYC-r with a non-IG partner concurrently with a cryptic t(12;21) in B-lymphoblastic leukemia: A case and prognostic significance

B-lymphoblastic leukemia (B-ALL) in children is characterized by recurrent chromosomal rearrangements that mostly have prognostic value. MYC rearrangements (MYC-r), typically associated with Burkitt lymphoma or mature B-cell neoplasms are infrequent in B-ALL. We report here a unique case of childhood B-ALL with concurrent MYC-r with a non-IG partner and a cryptic t(12;21). Leukemic cells had lymphoblastic morphology. Immunophenotypically, leukemic blasts were CD10 (+, slightly bright), CD15 (few +), CD19 (+), CD20 (+, partial), CD22 (+), CD34 (-), CD38 (+, slightly variably), CD45 (+, partial), cytoplasmic CD79a (+), HLA-DR (+), surface Ig (-), MPO (-), and TdT (+, partially). This immunophenotype was consistent with B-ALL. Cytogenetically, the karyotype was complex including a t(4;8)(q31;q24), and FISH analysis showed MYC-r, ETV6::RUNX1 and loss of ETV6 allele. The patient has been in complete remission for 11 years following the diagnosis. We reviewed cases of B-ALL with double leukemogenic alterations and MYC-r with non-IG partners to understand the clinical outcome in these rare patients.

Challenging Conventional Diagnostic Methods by Comprehensive Molecular Diagnostics: A Nationwide Prospective Comparison in Children With ALL

PURPOSE

Treatment stratification in ALL includes diverse (cyto)genetic aberrations, requiring diverse tests to yield conclusive data. We optimized the diagnostic workflow to detect all relevant aberrations with a limited number of tests in a clinically relevant time frame.

METHODS

In 467 consecutive patients with ALL (0-20 years), we compared RNA sequencing (RNAseq), fluorescence in situ hybridization (FISH), reverse transcriptase polymerase chain reaction (RT-PCR), karyotyping, single-nucleotide polymorphism (SNP) array, and multiplex ligation-dependent probe amplification (MLPA) for technical success, concordance of results, and turnaround time.

RESULTS

To detect stratifying fusions (ETV6::RUNX1, BCR::ABL1, ABL-class, KMT2Ar, TCF3::HLF, IGH::MYC), RNAseq and FISH were conclusive for 97% and 96% of patients, respectively, with 99% concordance. RNAseq performed well in samples with a low leukemic cell percentage or low RNA quality. RT-PCR for six specific fusions was conclusive for >99% but false-negative for six patients with alternatively fused exons. RNAseq also detected gene fusions not yet used for stratification in 14% of B-cell precursor-ALL and 33% of T-ALL. For aneuploidies and intrachromosomal amplification of chromosome 21, SNP array gave a conclusive result in 99%, thereby outperforming karyotyping, which was conclusive for 64%. To identify deletions in eight stratifying genes/regions, SNP array was conclusive in 99% and MLPA in 95% of patients, with 98% concordance. The median turnaround times were 10 days for RNAseq, 9 days for FISH, 10 days for SNP array, and <7 days for MLPA and RT-PCR in this real-world prospective study.

CONCLUSION

Combining RNAseq and SNP array outperformed current diagnostic tools to detect all stratifying genetic aberrations in ALL. The turnaround time is <15 days matching major treatment decision time points. Moreover, combining RNAseq and SNP array has the advantage of detecting new lesions for studies on prognosis and pathobiology.

Unraveling the Genetic Heterogeneity of Acute Lymphoblastic Leukemia Based on NGS Applications

Acute lymphoblastic leukemia (ALL) is a hematological neoplasm characterized by the clonal expansion of abnormal lymphoid precursors in bone marrow, which leads to alterations in the processes of cell differentiation and maturation as a consequence of genetic alterations. The integration of conventional methods, such as cytogenetics and immunophenotyping, and next-generation sequencing (NGS) has led to significant improvements at diagnosis and patient stratification; this has also allowed the discovery of several novel molecular entities with specific genetic variants that may drive the processes of leukemogenesis. Nevertheless, the understanding of the process of leukemogenesis remains a challenge since this disease persists as the most frequent cancer in children; it accounts for approximately one-quarter of adult acute leukemias, and the patient management may take into consideration the high intra- and inter-tumor heterogeneity and the relapse risk due to the various molecular events that can occur during clonal evolution. Some germline variants have been identified as risk factors or have been found to be related to the response to treatment. Therefore, better knowledge of the genetic alterations in B-ALL will have a prognostic impact from the perspective of personalized medicine. This review aims to compare, synthesize, and highlight recent findings concerning ALL obtained through NGS that have led to a better understanding of new molecular subtypes based on immunophenotypic characteristics, mutational profiles, and expression profiles.

Acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) is a haematological malignancy characterized by the uncontrolled proliferation of immature lymphoid cells. Over past decades, significant progress has been made in understanding the biology of ALL, resulting in remarkable improvements in its diagnosis, treatment and monitoring. Since the advent of chemotherapy, ALL has been the platform to test for innovative approaches applicable to cancer in general. For example, the advent of omics medicine has led to a deeper understanding of the molecular and genetic features that underpin ALL. Innovations in genomic profiling techniques have identified specific genetic alterations and mutations that drive ALL, inspiring new therapies. Targeted agents, such as tyrosine kinase inhibitors and immunotherapies, have shown promising results in subgroups of patients while minimizing adverse effects. Furthermore, the development of chimeric antigen receptor T cell therapy represents a breakthrough in ALL treatment, resulting in remarkable responses and potential long-term remissions. Advances are not limited to treatment modalities alone. Measurable residual disease monitoring and ex vivo drug response profiling screening have provided earlier detection of disease relapse and identification of exceptional responders, enabling clinicians to adjust treatment strategies for individual patients. Decades of supportive and prophylactic care have improved the management of treatment-related complications, enhancing the quality of life for patients with ALL.

Genetic alterations in lymphoblastic leukaemia

We present a practical guide for analyzing the genetic aspects of lymphoblastic leukaemia/lymphoma according to the 5th edition of the World Health Organization (WHO) classification of haematolymphoid neoplasms (WHO-HAEM5) issued in 2024. The WHO-HAEM5 acknowledges the increasing importance of genetics in the diagnosis of lymphoid neoplasia. Classification is based on the established genetic subtypes according to cell lineage, with precursor cell neoplasms followed by mature malignancies. This guide describes those genetic abnormalities in acute precursor B- and T-cell neoplasms required for risk stratification, and for treatment, providing diagnostic algorithms under the headings of 'essential' and 'desirable' diagnostic criteria.

Novel Biomarkers and Molecular Targets in ALL

PURPOSE OF REVIEW

Acute lymphoblastic leukemia (ALL) is a widely heterogeneous disease in terms of genomic alterations, treatment options, and prognosis. While ALL is considered largely curable in children, adults tend to have higher risk disease subtypes and do not respond as favorably to conventional chemotherapy. Identifying genomic drivers of leukemogenesis and applying targeted therapies in an effort to improve disease outcomes is an exciting focus of current ALL research. Here, we review recent updates in ALL targeted therapy and present promising opportunities for future research.

RECENT FINDINGS

With the utilization of next-generation sequencing techniques, the genomic landscape of ALL has greatly expanded to encompass novel subtypes characterized by recurrent chromosomal rearrangements, gene fusions, sequence mutations, and distinct gene expression profiles. The evolution of small molecule inhibitors and immunotherapies, and the exploration of unique therapy combinations are some examples of recent advancements in the field. Targeted therapies are becoming increasingly important in the treatment landscape of ALL to improve outcomes and minimize toxicity. Significant recent advancements have been made in the detection of susceptible genomic drivers and the use of novel therapies to target them.

Cytogenetics and genomics in pediatric acute lymphoblastic leukaemia

The last five decades have witnessed significant improvement in diagnostics, treatment and management of children with acute lymphoblastic leukaemia (ALL). These advancements have become possible through progress in our understanding of the genetic and biological background of ALL, resulting in the introduction of risk-adapted treatment and novel therapeutic targets, e.g., tyrosine kinase inhibitors for BCR::ABL1-positive ALL. Further advances in the taxonomy of ALL and the discovery of new genetic biomarkers and therapeutic targets, as well as the introduction of targeted and immunotherapies into the frontline treatment protocols, may improve management and outcome of children with ALL. In this review we describe the current developments in the (cyto)genetic diagnostics and management of children with ALL, and provide an overview of the most important advances in the genetic classification of ALL. Furthermore, we discuss perspectives resulting from the development of new techniques, including artificial intelligence (AI).

Cytogenetics in the management of B-cell acute lymphoblastic leukemia: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Cytogenetic analysis is mandatory at initial assessment of B-cell acute lymphoblastic leukemia (B-ALL) due to its diagnostic and prognostic value. Results from chromosome banding analysis and complementary FISH are taken into account in therapeutic protocols and further completed by other techniques (RT-PCR, SNP-array, MLPA, NGS, OGM). Indeed, new genomic entities have been identified by NGS, mostly RNA sequencing, such as Ph-like ALL that can benefit from targeted therapy. Here, we have attempted to establish cytogenetic guidelines by reviewing the most recent published data including the novel 5th World Health Organization and International Consensus Classifications. We also focused on newly described cytogenomic entities and indicate alternative diagnostic tools such as NGS technology, as its importance is vastly increasing in the diagnostic setting.