Pediatric acute lymphoblastic leukemia with t(1;19)/TCF3-PBX1 in Taiwan

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.

Incidence and Prognostic Impact of TCF3-PBX1 Fusion in Childhood Acute Lymphoblastic Leukemia: A Single Centre Experience

Molecular abnormalities in leukemic cells are important determinants of risk stratification in Pediatric acute lymphoblastic leukemia (ALL). TCF3-PBX1 fusion is one of the common aberrations in ALL with doubtful prognostic significance. Therefore, aim of our study is to revisit the clinical characteristics and outcome of this abnormality in children with ALL treated at our institute.Demographic, Clinical and treatment related characteristics of 539 newly diagnosed ALL patients from January 2009 and December 2018, < 18 years of age treated on BFM-95 protocol, was abstracted from the medical records. Clinical characteristics and outcome of children with and without TCF3-PBX1 fusion was compared.Incidence of TCF3-PBX1 fusion was observed in 24/539(4.4%) patients with a median age of 4 years (range 1-17). None of the patients in TCF3-PBX1 group had CNS or testicular disease at presentation. Day -8 prednisolone response and morphological remission at the end of induction was similar in both study groups. 5-year overall and event free survival for those with and without fusion was 75%, 70.1% and 79.5%, 69.5% respectively.The incidence of TCF3-PBX1 fusion in the present study was 4.4% and it does not have an independent prognostic significance.

The clinical outcomes and genomic landscapes of acute lymphoblastic leukemia patients with E2A-PBX1: A 10-year retrospective study

The clinical outcomes and genomic features of E2A-PBX1 (TCF3-PBX1)-positive B-cell acute lymphoblastic leukemia (B-ALL) patients remain unclear. A total of 137 patients carrying E2A-PBX1 among 3164 B-ALL patients between 2009 and 2019 were retrospectively analyzed. The 5-year overall survival (OS) and disease-free survival (DFS) rates of the whole cohort were 68.6% and 61.0%, respectively. Age [DFS, p = 0.037; cumulative incidence of relapse (CIR), p = 0.005] and the level of minimal residual disease (MRD) after induction chemotherapy (OS, p = 0.020; DFS, p = 0.002; CIR, p = 0.006) were independent risk factors. In adolescents/adults, allogeneic hematopoietic stem cell transplantation (allo-HSCT) at first complete remission (CR1) significantly improved the 5-year prognosis (OS, p < 0.001; DFS, p < 0.001; CIR, p < 0.001). Haploidentical HSCT decreased the CIR compared with human leukocyte antigen-matched HSCT in adolescents/adults (p = 0.017). Mutations in PBX1, PAX5, CTCF and SETD2, amplification of AKT3, and deletion of CDKN2A/B were common in the total cohort, while transcriptome differences were found in the cell cycle, nerve growth factor (NGF) signaling pathway and transcriptional regulation by TP53 between adolescents/adults and children. Patients with multiple subclones at diagnosis tended to have unfavorable 3-year prognoses (DFS, p = 0.010; CIR, p = 0.021). Leukemia clones with DNA repair gene mutations showed aggressive and treatment-refractory phenotypes in this subtype of ALL. Our study indicated that age, the level of MRD and DNA repair gene mutations were associated with E2A-PBX1-positive B-ALL outcomes. Allo-HSCT, especially haploidentical HSCT, could improve the prognosis of adolescent/adult patients.

Cesarean Section Is Associated with an Increased Risk of Acute Lymphoblastic Leukemia and Hepatoblastoma in Children from Minnesota

BACKGROUND

In recent decades, Cesarean section (C-section) rates have increased. C-section is hypothesized to negatively impact the developing immune system by altering activation of the hypothalamic-pituitary-adrenal axis and the infant microbiome, among other mechanisms, thereby potentially modulating childhood cancer risk.

METHODS

Using linked birth and cancer registry data from Minnesota (1976-2014), we included individuals ages 0-14 at diagnosis with one of 19 cancers. Cases and controls were frequency matched by birth year. We used logistic regression to estimate ORs and 95% confidence intervals (95% CI) as the measure of association between C-section and cancer. We assessed sex-C-section interactions for each cancer and conducted stratified analyses in acute lymphoblastic leukemia (ALL) for birth year, age at diagnosis, and maternal race.

RESULTS

There were 3,166 cases and 20,589 controls. One third (n = 1,174) of controls born during 2004-2014 were delivered via C-section compared with 42.2% of cases (n = 285). C-section was associated with ALL (n = 819; OR: 1.20; 95% CI: 1.01-1.43) and hepatoblastoma (n = 50; OR: 1.89; 95% CI: 1.03-3.48), particularly among females (ALL OR: 1.34; 95% CI: 1.04-1.72; hepatoblastoma OR: 3.87; 95% CI: 1.30-11.57). The risk of ALL was highest during 2005-2014 (OR: 1.62; 95% CI: 1.11-2.34) and among children ages 1-5 years (OR: 1.28; 95% CI: 1.02-1.61).

CONCLUSIONS

C-section was associated with an increased risk of ALL and hepatoblastoma.

IMPACT

These associations require investigation to determine causality and rule out confounding by indication or reverse causality. The mechanisms underlying these associations may depend on neonatal immune system processes altered during C-section deliveries.

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

OBJECTIVE

The aim of this study was to review clinical outcomes and prognosis of paediatric patients with acute lymphoblastic leukaemia (ALL) with TCF3-PBX1 rearrangement.

PATIENTS

All children in Hong Kong diagnosed with ALL with TCF3-PBX1 rearrangement over the past two decades were included.

METHODS

Six hundred and twenty-four newly diagnosed patients with ALL from four consecutive studies were enrolled from 1997 to 2016. Patients carrying TCF3-PBX1 rearrangement and patients at intermediate risk without the gene expression were compared for clinical characteristics, overall survival and event-free survival (EFS).

RESULTS

The TCF3-PBX1 rearrangement was detected in 30 of 624 patients (4.8%). Results were consistent across the consecutive clinical trials employed in the past two decades. Compared with 239 intermediate risk patients without TCF3-PBX1 rearrangement, the 5-year overall survival and EFS for patients with TCF3-PBX1 rearrangement was superior, with both at 100% (P = 0.12 and P = 0.029).

CONCLUSION

This population-based study over the past 20 years demonstrated that patients with TCF3-PBX1 rearrangement had favourable EFS compared with other intermediate risk patients treated with a similar chemotherapy backbone.

Treatment and biology of pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. In the past ALL was intractable but now the survival probability is as high as 80-90%. Improved supportive care, treatment stratification based on relapse risk, biological features of leukemic cells, and optimization of treatment regimens by nationwide and international collaboration have contributed to this dramatic improvement. While including traditional risk factors (e.g. age and leukocyte count at diagnosis), the treatment has been modified based on biological characteristics (aneuploidy and translocation) and treatment response (assessed by minimal residual disease). Treatment for pediatric ALL typically consists of induction therapy with steroids, vincristine, and asparaginase with or without anthracycline, followed by multi-agent consolidation including high-dose methotrexate and re-induction therapy. After consolidation, less intensive maintenance therapy is required for 1-2 years to maintain event-free survival. Recently, using advanced genomic analysis technology, novel sentinel genomic alterations that may provide more precise stratification or therapeutic targets, were identified. Moreover, in the last decade germline variations have been recognized as similarly important contributors to understanding the etiology and sensitivity of ALL to treatment. A more individualized approach based on genomic features (somatic and germline) and treatment response, the introduction of newly developed agents such as molecular targeted drugs or immunotherapy, and social support including long-term follow up are required for further improvement.