Excellent outcome of acute lymphoblastic leukaemia with TCF3-PBX1 rearrangement in Hong Kong

The advances of E2A-PBX1 fusion in B-cell acute lymphoblastic Leukaemia

The E2A-PBX1 gene fusion is a common translocation in B-cell acute lymphoblastic leukaemia. Patients harbouring the E2A-PBX1 fusion gene typically exhibit an intermediate prognosis. Furthermore, minimal residual disease has unsatisfactory prognostic value in E2A-PBX1 B-cell acute lymphoblastic leukaemia. However, the mechanism of E2A-PBX1 in the occurrence and progression of B-cell acute lymphoblastic leukaemia is not well understood. Here, we mainly review the roles of E2A and PBX1 in the differentiation and development of B lymphocytes, the mechanism of E2A-PBX1 gene fusion in B-cell acute lymphoblastic leukaemia, and the potential therapeutic approaches.

Molecular characterization of TCF3::PBX1 chromosomal breakpoints in acute lymphoblastic leukemia and their use for measurable residual disease assessment

The translocation t(1;19)(q23;p13) with the resulting chimeric TCF3::PBX1 gene is the third most prevalent recurrent chromosomal translocation in acute lymphoblastic leukemia and accounts for 3-5% of cases. The molecular background of this translocation has been incompletely studied, especially in adult cases. We characterized the chromosomal breakpoints of 49 patients with TCF3::PBX1 and the corresponding reciprocal PBX1::TCF3 breakpoints in 15 cases at the molecular level, thus providing an extensive molecular overview of this translocation in a well-defined study patient population. Breakpoints were found to be remarkably clustered not only in TCF3 but also in PBX1. No association with DNA repeats or putative cryptic recombination signal sequence sites was observed. A simplified detection method for breakpoint identification was developed and the feasibility of patient-specific chromosomal break sites as molecular markers for detecting measurable residual disease (MRD) was explored. A highly sensitive generic real-time PCR for MRD assessment using these breakpoint sequences was established that could serve as a useful alternative to the classical method utilizing rearranged immune gene loci. This study provides the first extensive molecular data set on the chromosomal breakpoints of the t(1;19)/TCF3::PBX1 aberration in adult ALL. Based on the obtained data a generic MRD method was developed that has several theoretical advantages, including an on average higher sensitivity and a greater stability of the molecular marker in the course of disease.

Prognostic factors of childhood acute lymphoblastic leukemia with TCF3::PBX1 in CCCG-ALL-2015: A multicenter study

BACKGROUND

Contemporary risk-directed treatment has improved the outcome of patients with acute lymphoblastic leukemia (ALL) and TCF3::PBX1 fusion. In this study, the authors seek to identify prognostic factors that can be used to further improve outcome.

METHODS

The authors studied 384 patients with this genotype treated on Chinese Children's Cancer Group ALL-2015 protocol between January 1, 2015 and December 31, 2019. All patients provisionally received intensified chemotherapy in the intermediate-risk arm without prophylactic cranial irradiation; those with high minimal residual disease (MRD) ≥1% at day 46 (end) of remission induction were candidates for hematopoietic cell transplantation.

RESULTS

The overall 5-year event-free survival was 84.4% (95% confidence interval [CI], 80.6-88.3) and 5-year overall survival 88.9% (95% CI, 85.5-92.4). Independent factors associated with lower 5-year event-free survival were male sex (80.4%, [95% CI, 74.8-86.4] vs. 88.9%, [95% CI, 84.1-93.9] in female, p = .03) and positive day 46 MRD (≥0.01%) (62.1%, [95% CI, 44.2-87.4] vs. 87.1%, [95% CI, 83.4-90.9] in patients with negative MRD, p < .001). The presence of testicular leukemia at diagnosis (n = 10) was associated with particularly dismal 5-year event-free survival (33.3% [95% CI, 11.6-96.1] vs. 83.0% [95% CI, 77.5-88.9] in the other 192 male patients, p < .001) and was an independent risk factor (hazard ratio [HR], 5.7; [95% CI, 2.2-14.5], p < .001).

CONCLUSIONS

These data suggest that the presence of positive MRD after intensive remission induction and testicular leukemia at diagnosis are indicators for new molecular therapeutics or immunotherapy in patients with TCF3::PBX1 ALL.

Clonal dynamics in pediatric B-cell precursor acute lymphoblastic leukemia with very early relapse

INTRODUCTION

One-quarter of the relapses in children with B-cell precursor acute lymphoblastic leukemia (BCP-ALL) occur very early (within 18 months, before completion of treatment), and prognosis in these patients is worse compared to cases that relapse after treatment has ended.

METHODS

In this study, we performed a genomic analysis of diagnosis-relapse pairs of 12 children who relapsed very early, followed by a deep-sequencing validation of all identified mutations. In addition, we included one case with a good initial treatment response and on-treatment relapse at the end of upfront therapy.

RESULTS

We observed a dynamic clonal evolution in all cases, with relapse almost exclusively originating from a subclone at diagnosis. We identified several driver mutations that may have influenced the outgrowth of a minor clone at diagnosis to become the major clone at relapse. For example, a minimal residual disease (MRD)-based standard-risk patient with ETV6-RUNX1-positive leukemia developed a relapse from a TP53-mutated subclone after loss of the wildtype allele. Furthermore, two patients with TCF3-PBX1-positive leukemia that developed a very early relapse carried E1099K WHSC1 mutations at diagnosis, a hotspot mutation that was recurrently encountered in other very early TCF3-PBX1-positive leukemia relapses as well. In addition to alterations in known relapse drivers, we found two cases with truncating mutations in the cohesin gene RAD21.

CONCLUSION

Comprehensive genomic characterization of diagnosis-relapse pairs shows that very early relapses in BCP-ALL frequently arise from minor subclones at diagnosis. A detailed understanding of the therapeutic pressure driving these events may aid the development of improved therapies.

Genetic Alterations in Childhood Acute Lymphoblastic Leukemia: Interactions with Clinical Features and Treatment Response

Acute lymphoblastic leukemia (ALL) is the most common cancer among children. This aggressive cancer comprises multiple molecular subtypes, each harboring a distinct constellation of somatic, and to a lesser extent, inherited genetic alterations. With recent advances in genomic analyses such as next-generation sequencing techniques, we can now clearly identify >20 different genetic subtypes in ALL. Clinically, identifying these genetic subtypes will better refine risk stratification and determine the optimal intensity of therapy for each patient. Underpinning each genetic subtype are unique clinical and therapeutic characteristics, such as age and presenting white blood cell (WBC) count. More importantly, within each genetic subtype, there is much less variability in treatment response and survival outcomes compared with current risk factors such as National Cancer Institute (NCI) criteria. We review how this new taxonomy of genetic subtypes in childhood ALL interacts with clinical risk factors used widely, i.e., age, presenting WBC, IKZF1del, treatment response, and outcomes.

Screening of immune biomarkers in different breeds of chickens infected with J subgroup of avian leukemia virus by proteomic

Avian leucosis (AL) is a disease characterized by tumors and is caused by the avian leukosis virus (ALV). Because of the high variability of viruses and complex pathogenic mechanisms, screening and breeding J subgroup of ALV (ALV-J) resistant avian breeds is one of the strategies for prevention and treatment of AL, thus screening of significant immune markers is needed to promote the development of disease-resistant breeds. In this study, data-independent acquisition (DIA) technology was used to detect the DEPs of three breeds of chicken according to different comparison to investigate the potential markers. Results showed special DEPs for spleen development of each breed were detected, such as PCNT, DDB2, and ZNF62. These DEPs were involved in intestinal immune network used in production of IgA signaling pathways and related to immune response which can be used as potential markers for spleen development in different breeds. The DEPs such as RAB44 and TPN involved in viral myocarditis, transcriptional misregulation in cancer, and tuberculosis can be used as potential markers of spleen immune response after ALV-J infection in chickens. Pair-wise analysis was performed for the three breeds after the infection of ALV-J. The proteins such as RFX1, TAF10, and VH1 were differently expressed between three breeds. These DEPs involved in antigen processing and expression, acute myelogenous leukemia, and viral carcinogenesis can be used as potential immune markers after ALV-J infection of different genetic backgrounds. The screening of potential markers at protein level provides a strong theoretical research basis for disease resistance breeding in poultry.

DNA Methylation Clusters and Their Relation to Cytogenetic Features in Pediatric AML

Acute Myeloid Leukemia (AML) is characterized by recurrent genetic and cytogenetic lesions that are utilized for risk stratification and for making treatment decisions. In recent years, methylation dysregulation has been extensively studied and associated with risk groups and prognosis in adult AML, however, such studies in pediatric AML are limited. Moreover, the mutations in epigenetic genes such as DNMT3A, IDH1 or IDH2 are almost absent or rare in pediatric patients as compared to their abundance in adult AML. In the current study, we evaluated methylation patterns that occur with or independent of the well-defined cytogenetic features in pediatric AML patients enrolled on multi-site AML02 clinical trial (NCT00136084). Our results demonstrate that unlike adult AML, cytosine DNA methylation does not result in significant unique clusters in pediatric AML, however, DNA methylation signatures correlated significantly with the most common and recurrent cytogenetic features. Paired evaluation of DNA methylation and expression identified genes and pathways of biological relevance that hold promise for novel therapeutic strategies. Our results further demonstrate that epigenetic signatures occur complimentary to the well-established chromosomal/mutational landscape, implying that dysregulation of oncogenes or tumor suppressors might be leveraging both genetic and epigenetic mechanisms to impact biological pathways critical for leukemogenesis.