Nationwide study of pediatric B-cell precursor acute lymphoblastic leukemia with chromosome 8q24/MYC rearrangement in Japan

Causes of death and treatment-related mortality in newly diagnosed childhood acute lymphoblastic leukemia treatment with Chinese Children's Cancer Group study ALL-2015

To investigate the possible risk factors for death at post-treatment in children with acute lymphoblastic leukemia (ALL). A multivariate competing risk analysis was performed to retrospectively analyze the data of children with ALL who died after treatment with CCCG-ALL-2015 in China and to determine the possible risk factors for death at post-treatment in children with ALL. Age at the first diagnosis of ≥10 years; final risk level of high-risk; D19 minimal residual disease (MRD) (≥0.01%) and D46 MRD (≥0.01%); genetic abnormalities, such as KMT2A-rearrangement, c-Myc rearrangement, and PDGFRB rearrangement; and the presence of CNS3 (all P values, <0.05) were identified as independent risk factors, whereas the risk level at the first diagnosis of low-risk (LR) and ETV6::RUNX1 positivity was considered as independent protective factors of death in children with ALL. Among the 471 cases of death, 45 cases were treated with CCCG-ALL-2015 only, and 163 (34.61%) were treatment-related, with 62.42% due to severe infections. 55.83% of treatment-related mortality (TRM) occurred in the early phase of treatment (induction phase). TRM has a significant impact on the overall survival of pediatric patients with ALL. Moreover, the CCCG-ALL-2015 regimen has a better safety profile for treating children with ALL, with rates close to those in developed countries (registration number: ChiCTR-IPR-14005706; date of registration: June 4, 2014).

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

Rarely, immunophenotypically immature B-cell precursor acute lymphoblastic leukemia (BCP-ALL) carries an immunoglobulin- MYC rearrangement (IG-MYC-r). This can result in diagnostic confusion with Burkitt lymphoma/leukemia and use of individualized treatment schedules of unproven efficacy. Here we compare the molecular characteristics of these conditions and investigate historic clinical outcome data. We identified 90 cases registered in a national BCP-ALL clinical trial/registry. When present, diagnostic material underwent cytogenetic, exome, methylome and transcriptome analyses. The outcomes analyzed were 3-year event-free survival and overall survival. IG-MYC-r was identified in diverse cytogenetic backgrounds, co-existing with either established BCP-ALL-specific abnormalities (high hyperdiploidy, n=3; KMT2A-rearrangement, n=6; iAMP21, n=1; BCR-ABL1, n=1); BCL2/BCL6-rearrangements (n=15); or, most commonly, as the only defining feature (n=64). Within this final group, precursor-like V(D)J breakpoints predominated (8/9) and KRAS mutations were common (5/11). DNA methylation identified a cluster of V(D)J-rearranged cases, clearly distinct from Burkitt leukemia/lymphoma. Children with IG-MYC-r within that subgroup had a 3-year event-free survival of 47% and overall survival of 60%, representing a high-risk BCP-ALL. To develop effective management strategies this group of patients must be allowed access to contemporary, minimal residual disease-adapted, prospective clinical trial protocols.

Single-Cell Sequencing: Biological Insight and Potential Clinical Implications in Pediatric Leukemia

Single-cell sequencing (SCS) provides high-resolution insight into the genomic, epigenomic, and transcriptomic landscape of oncohematological malignancies including pediatric leukemia, the most common type of childhood cancer. Besides broadening our biological understanding of cellular heterogeneity, sub-clonal architecture, and regulatory network of tumor cell populations, SCS can offer clinically relevant, detailed characterization of distinct compartments affected by leukemia and identify therapeutically exploitable vulnerabilities. In this review, we provide an overview of SCS studies focused on the high-resolution genomic and transcriptomic scrutiny of pediatric leukemia. Our aim is to investigate and summarize how different layers of single-cell omics approaches can expectedly support clinical decision making in the future. Although the clinical management of pediatric leukemia underwent a spectacular improvement during the past decades, resistant disease is a major cause of therapy failure. Currently, only a small proportion of childhood leukemia patients benefit from genomics-driven therapy, as 15-20% of them meet the indication criteria of on-label targeted agents, and their overall response rate falls in a relatively wide range (40-85%). The in-depth scrutiny of various cell populations influencing the development, progression, and treatment resistance of different disease subtypes can potentially uncover a wider range of driver mechanisms for innovative therapeutic interventions.

Genetic features of precursor B-cell phenotype Burkitt leukemia with IGH-MYC rearrangement

Background

An atypical form of Burkitt leukemia/lymphoma (BL), BL with a phenotype of precursor B‐cells (preBLL), is listed in the WHO Classification. Recent reports suggested that preBLL and classical BL could be distinguished by the differences in IG‐MYC translocation architecture and an additional mutated genes profile. The characteristics of classical BL are IG‐MYC by aberrant somatic hypermutation or class switch recombination, and BL‐specific gene mutations such as MYC, ID3, and CCND3. Meanwhile, preBLL is characterized by IG‐MYC due to aberrant VDJ recombination and mutations in NRAS and KRAS. However, it is not clear whether all preBLL cases can be differentiated. This report investigated the molecular characteristics of an infant preBLL case, with a more advanced stage of maturity than typical preBLL.

Case

The patient showed BL‐like morphology with IGH‐MYC rearrangement. In the immunophenotyping, CD20 and surface immunoglobulin were negative, whereas other markers were consistent with BL. To evaluate the genetic contribution, we performed whole‐exome sequencing. The breakpoint analysis revealed the IG‐MYC occurred due to an aberrant VDJ recombination. Meanwhile, additional somatic mutations were detected in FBXO11, one of the mutant genes specific to BL. In the analysis of the specimen in complete remission, mutation in KRAS, frequently mutated in preBLL, was detected with low frequency, suggesting somatic mosaicism.

Conclusion

The present case showed the characteristics of both typical preBLL and classical BL. Because preBLL includes atypical cases such as the present case, further studies are required to elucidate preBLL features.

Burkitt leukemia with precursor B-cell features that developed after ruxolitinib treatment in a patient with hydroxyurea-refractory JAK2V617F-myeloproliferative neoplasm

A 62-year-old woman, who had a 16-year history of JAK2^V617F-mutated myeloproliferative neoplasm (MPN), developed Burkitt leukemia (BL) 16 months after treatment with ruxolitinib to control hydroxyurea-refractory conditions. BL cells were CD10⁺, CD19⁺, CD20⁻, CD34⁻, cytoplasmic CD79a⁺, and TdT⁺, and lacked surface immunoglobulins but expressed the cytoplasmic μ heavy chain. In the bone marrow, nuclear MYC⁺ BL cells displaced the MPN tissues. t(8;14)(q24;q32) occurred at a CG dinucleotide within MYC exon 1 and at the IGHJ3 segment, and an N-like segment was inserted at the junction. The V-D-J sequence of the non-translocated IGH allele had the unmutated configuration. DNA from peripheral blood at a time of the course of MPN exhibited homozygous JAK2^V617F mutation, while that at BL development included both JAK2^V617F and wild-type DNAs. Although the association between JAK1/2 inhibitor therapy for MPN and secondary development of aggressive B-cell neoplasm remains controversial, this report suggests that, in selected patients, close monitoring of clonal B-cells in the BM is required before and during treatment with JAK1/2 inhibitors.

Extranodal presentation of a lymphoma with precursor B-cell phenotype and translocation t(8;14) in South Africa

Introduction

A rare entity of a B-cell malignancy with precursor B-cell phenotype and concomitant translocation t(8;14) or variant MYC translocation exists. These cases show clinical, pathological and molecular overlap between precursor B-lymphoblastic leukaemia or lymphoma and Burkitt leukaemia or lymphoma (BLL).

Case presentation

We report a case from February 2019 at the Charlotte Maxeke Johannesburg Academic Hospital, South Africa, of a 9-month-old infant with a predominantly extracranial soft tissue mass showing extradural extension. There was no involvement of the peripheral blood or bone marrow. Fine needle aspiration and Tru-Cut biopsy of the soft tissue scalp mass showed the tumour to be of precursor B-cell phenotype. Contrastingly, an immunophenotypic assessment revealed a high S-phase fraction and raised concern for BLL. This prompted testing for the translocation t(8;14) by fluorescence in-situ hybridisation analysis, which confirmed this aberration.

Management and outcome

Based on the published experience of other centres, the patient was initiated on a BLL protocol. Despite an excellent clinical response, the patient succumbed to neutropenic sepsis six months after diagnosis.

Conclusion

Leukaemia or lymphoma with translocation t(8;14) or variant MYC translocation and precursor B-cell phenotype is a rare entity with a varied clinical presentation. This poses a challenge for diagnosis and classification and a clinical dilemma for the choice of treatment.