TP53 Germline Variations Influence the Predisposition and Prognosis of B-Cell Acute Lymphoblastic Leukemia in Children

Overt and covert genetic causes of pediatric acute lymphoblastic leukemia

Pediatric acute lymphoblastic leukemia (pALL) is the most common childhood malignancy, yet its etiology remains incompletely understood. However, over the course of three waves of germline genetic research, several non-environmental causes have been identified. Beginning with trisomy 21, seven overt cancer predisposition syndromes (CPSs)-characterized by broad clinical phenotypes that include an elevated risk of pALL-were first described. More recently, newly described CPSs conferring high risk of pALL are increasingly covert, with six exhibiting only minimal or no non-cancer features. These 13 CPSs now represent the principal known hereditary causes of pALL, and human pangenomic data indicates a strong negative selection against mutations in the genes associated with these conditions. Collectively they affect approximately 1 in 450 newborns, of which just a minority will develop the disease. As evidenced by tailored leukemia care protocols for children with trisomy 21, there is growing recognition that CPSs warrant specialized diagnostic, therapeutic, and long-term management strategies. In this review, we investigate the evidence that the 12 other CPSs associated with high risk of pALL may also see benefits from specialized care - even if these needs are often incompletely mapped or addressed in the clinic. Given the rarity of each syndrome, collaborative international research and shared data initiatives will be crucial for advancing knowledge and improving outcomes for these patients.

Genetically Distinct Acute Megakaryoblastic Leukemia following Low Hypodiploid B-Lymphoblastic Leukemia linked by TP53 Mutation

We report a case of acute myeloid leukemia with megakaryoblastic differentiation (AMKL) that developed after an initial B-lymphoblastic leukemia (B-ALL) with low hypodiploidy. Although the AMKL was initially thought either to be a phenotypic change from the original B-ALL or to have arisen as a result of treatment (acute myeloid leukemia, post cytotoxic therapy, AML-pCT [WHO]; AML, therapy related [ICC]), genetic evaluation of both the AMKL and the B-ALL suggest that neither of these considerations was correct. Rather, the AMKL did not harbor the most common genetic hallmark of AML-pCT-rearrangement of KMT2- and was genetically distinct from the B-ALL. Both the B-ALL and the AMKL, however, showed an identical TP53 mutation by next generation sequencing (NGS), while germline testing was negative for this mutant allele. Hence, either the patient had a tissue restricted constitutional TP53 mutation or had a somatic mutation in a multipotent hematopoietic precursor. This case highlights the necessity for close monitoring of patients with TP53-mutant tumors, as they may develop multiple lesions despite negative germline testing.

TP53 deletion as an MRD-dependent risk factor in childhood B-ALL: A post hoc analysis from a prospective cohort

The effect of TP53 alterations on childhood B-cell acute lymphoblastic leukemia (B-ALL) remains unclear. To investigate the prognostic value of TP53 deletion (TP53 del ) and TP53 mutation (TP53 mut ), this post hoc study used fluorescence in situ hybridization test to detect TP53 del in 907 newly diagnosed B-ALL patients from a prospective cohort of Chinese Children's Cancer Group ALL-2015 trial. Targeted gene sequencing was used to identify TP53 mut in 342 out of the 907 patients. TP53 del was detected in 4.4% of patients. The frequency of hypodiploidy was higher in TP53 del subgroup (7.5% vs. 0.5%, p = 0.002), but patients with TP53 del were less likely to have other recurrent genetic abnormalities, including BCR::ABL1, ETV6::RUNX1, TCF3::PBX1 and KMT2A rearrangements. Univariable and multivariable analyses indicated that TP53 del was an independent risk factor for overall survival (OS) and disease-free survival (DFS). Furthermore, stratification analysis revealed that TP53 del was associated with lower 5-year DFS in patients with positive minimal residual disease (MRD) after induction in the intermediate-risk group (0.0% vs. 58.0% [95% confidence interval [CI] 49.2%-68.3%], p < 0.001), suggesting an MRD-dependent pattern. However, somatic TP53 mut was not associated with poor survival (81.8% [95% CI 61.9%-100.0%] vs. 84.9% [95% CI 81.1%-89.0%], p = 0.971). In summary, TP53 del may serve as a predictor for poor prognosis in pediatric B-ALL. In particular, children in the intermediate-risk group with positive MRD and TP53 del may require more aggressive treatment.

Germline pathogenic variation impacts somatic alterations and patient outcomes in pediatric CNS tumors

The contribution of rare pathogenic/likely pathogenic (P/LP) germline variants to pediatric central nervous system (CNS) tumor development remains understudied. Here, we characterized the prevalence and clinical significance of germline P/LP variants in cancer predisposition genes across 830 CNS tumor patients from the Pediatric Brain Tumor Atlas (PBTA). We identified germline P/LP variants in 24.2% (201/830) of patients and the majority (154/201) lacked clinical reporting of genetic tumor syndromes. Among P/LP carriers, 30.7% had putative somatic second hits or loss of function tumor alterations. Finally, we linked pathogenic germline variation with novel somatic events and patient survival to highlight the impact of germline variation on tumorigenesis and patient outcomes.

From regulation to deregulation of p53 in hematologic malignancies: implications for diagnosis, prognosis and therapy

The p53 protein, encoded by the TP53 gene, serves as a critical tumor suppressor, playing a vital role in maintaining genomic stability and regulating cellular responses to stress. Dysregulation of p53 is frequently observed in hematological malignancies, significantly impacting disease progression and patient outcomes. This review aims to examine the regulatory mechanisms of p53, the implications of TP53 mutations in various hematological cancers, and emerging therapeutic strategies targeting p53. We conducted a comprehensive literature review to synthesize recent findings related to p53's multifaceted role in hematologic cancers, focusing on its regulatory pathways and therapeutic potential. TP53 mutations in hematological malignancies often lead to treatment resistance and poor prognosis. Current therapeutic strategies, including p53 reactivation and gene therapy, show promise in improving treatment outcomes. Understanding the intricacies of p53 regulation and the consequences of its mutations is essential for developing effective diagnostic and therapeutic strategies in hematological malignancies, ultimately enhancing patient care and survival.

Assessment of cancer predisposition syndromes in children with leukemia and solid tumors: germline-genomic profiling and clinical features in a series of cases

Cancer predisposition syndromes (CPS) are a group of genetic disorders that increase the risk of various cancers. Identifying CPS has a significant impact on the treatment plan, screening and follow-up strategy, and genetic counseling of the family. However, in children, it goes underdiagnosed in most clinical setups, especially in low- and middle-income (LMIC) countries. In the present study, we screened 60 pediatric oncology patients for a possible CPS based on pre-defined selection criteria. Six patients met the criteria, three of whom had hematological malignancy, while the remaining three had sarcoma. Whole exome sequencing was performed in the selected patients to confirm the diagnosis. Germline mutation in CPS-related genes was discovered in five of six cases, including novel mutations discovered in two. An adverse outcome was observed in all five patients with underlying cancer predisposition syndrome, with three having relapsed and two having progressive disease. Our study reflects a prevalence of 10% underlying CPS in a limited cohort of patient based on the phenotype-genotype approach in our cohort. Using pre-defined clinical selection criteria, screening can be directed to a high-risk patient cohort with high-pick up rate for CPS. The selection criteria could be utilized in any LMIC-based clinical setup for pediatric cancer patients who may benefit from modification of treatment as well as genetic counseling.

Current insights and future directions of Li-Fraumeni syndrome

Li-Fraumeni syndrome is a rare yet serious hereditary cancer predisposition syndrome, marked by a significant early-life increased risk of developing cancer. Primarily caused by germline mutations in the TP53 tumor suppressor gene, Li-Fraumeni syndrome is associated with a wide range of malignancies. Clinical management of Li-Fraumeni syndrome could be challenging, especially the lifelong surveillance and follow-up of patients which requires a multidisciplinary approach. Emerging insights into the molecular and clinical basis of Li-Fraumeni syndrome, coupled with advances in genomic technologies and targeted therapies, offer promise in optimizing risk assessment, early detection, and treatment strategies tailored to the unique clinical and molecular profiles of affected individuals. This review discusses Li-Fraumeni syndrome in more depth, reviewing molecular, genomic, epidemiological, clinical, and therapeutic aspects of this disease.

Decitabine consolidation after CD19/CD22 CAR-T therapy as a novel maintenance treatment significantly improves survival outcomes in relapsed/refractory B-ALL patients

OBJECTIVE

We aimed to evaluate the efficacy of decitabine consolidation after treatment with CD19/CD22 chimeric antigen receptor T-cell (CAR-T) for patients with relapsed/refractory B-cell acute lymphoblastic leukaemia (r/r B-ALL).

METHODS

We retrospectively analysed 48 patients with r/r B-ALL who received CD19/CD22 CAR-T therapy between September 2017 and May 2021. Sixteen patients received decitabine consolidation (20 mg/m2/day for 5 days at 3-month intervals) after CAR-T therapy (DAC group), while 32 patients did not receive decitabine consolidation (CON group). Overall survival (OS), leukaemia-free survival (LFS), and cumulative incidence of relapse (CIR) were evaluated in both groups. Time-to-event analysis was performed using the Kaplan-Meier method.

RESULTS

The median follow-up periods in the DAC and CON groups were 41.2 months and 28.6 months, respectively. The 4-year OS and 4-year LFS rates in both groups were 93.3 % and 64.3 % (P=0.029) and 87.5 % and 55.9 % (P=0.059), respectively. The 1-year CIR was 6.25 % and 28.6 %, respectively. Univariate and multivariate Cox regression analyses showed that decitabine consolidation after CAR-T therapy was significantly associated with superior OS (hazard ratio [HR]: 0.121, 95 % confidence interval [CI]: 0.015-0.947, P=0.044), and bridging to haematopoietic stem cell transplantation after CAR-T therapy was significantly associated with superior LFS (HR: 0.279, 95 %CI: 0.093-0.840, P=0.023).

CONCLUSIONS

Our study recommends decitabine consolidation after CD19/CD22 CAR-T therapy as a novel maintenance strategy to improve the survival outcomes of patients with r/r B-ALL.

Case report: Germline CHEK2 mutation is associated with a giant cell glioblastoma

Giant cell glioblastoma often exhibits genome instability and is frequently associated with mutations in genes involved in DNA repair pathways including TP53 and DNA mismatch repair genes. Several germline mutations have been identified in giant cell glioblastoma, including mutations of MSH1 and MSH2, TP53, and POLE. We have documented a case of a germline mutation in CHEK2, another gene crucial to DNA repair, in a patient with giant cell glioblastoma. The CHEK2 mutation was inherited from the patient's father, who had a history of gastric cancer and renal cell carcinoma. In addition to the germline CHEK2 mutation, the giant cell glioblastoma exhibited a genome-wide loss of heterozygosity, a characteristic observed in a subset of giant cell glioblastomas. Additional mutations detected in the tumor included TP53, PTEN, and a PTPRZ1-MET fusion. This represents the first reported case of a CHEK2 germline mutation in giant cell glioblastoma, further supporting the significance of impaired DNA repair mechanisms in the development of this disease.

Update on Genetic Counselor Practice and Recommendations for Pediatric Cancer Predisposition Evaluation and Surveillance

In July 2023, the American Association for Cancer Research held the second Childhood Cancer Predisposition Workshop, at which international experts in pediatric cancer predisposition met to update the previously published 2017 consensus statements on pediatric cancer predisposition syndromes. Since 2017, advances in tumor and germline genetic testing and increased understanding of cancer predisposition in patients with pediatric cancer have led to significant changes in clinical care. Here, we provide an updated genetic counseling framework for pediatric oncology professionals. The framework includes referral indications and timing, somatic and germline genetic testing options, testing for adult-onset cancer predisposition syndromes in children with and without cancer, evolving genetic counseling models to meet the increased demand for genetic testing, barriers to cancer genetic testing and surveillance in children, and psychosocial and equity considerations regarding cancer genetic testing and surveillance in children. Adaptable genetic counseling services are needed to provide support to pediatric oncology provider teams and diverse patients with pediatric cancer, cancer predisposition, and their families.

Li-Fraumeni Syndrome: Imaging Features and Guidelines

Li-Fraumeni syndrome (LFS) is a rare autosomal dominant familial cancer syndrome caused by germline mutations of the tumor protein p53 gene (TP53), which encodes the p53 transcription factor, also known as the "guardian of the genome." The most common types of cancer found in families with LFS include sarcomas, leukemia, breast malignancies, brain tumors, and adrenocortical cancers. Osteosarcoma and rhabdomyosarcoma are the most common sarcomas. Patients with LFS are at increased risk of developing early-onset gastric and colon cancers. They are also at increased risk for several other cancers involving the thyroid, lungs, ovaries, and skin. The lifetime risk of cancer in individuals with LFS is greater than 70% in males and greater than 90% in females. Some patients with LFS develop multiple primary cancers during their lifetime, and guidelines have been established for screening these patients. Whole-body MRI is the preferred modality for annual screening of these patients. The management guidelines for patients with LFS vary, as these individuals are more susceptible to developing radiation-induced cancers-for example, women with LFS and breast cancer are treated with total mastectomy instead of lumpectomy with radiation to the breast. The authors review the role of imaging, imaging guidelines, and imaging features of tumors in the setting of LFS. ©RSNA, 2024 Supplemental material is available for this article.

Germ line genetic NBN variation and predisposition to B-cell acute lymphoblastic leukemia in children

ABSTRACT

Biallelic mutation in the DNA-damage repair gene NBN is the genetic cause of Nijmegen breakage syndrome, which is associated with predisposition to lymphoid malignancies. Heterozygous carriers of germ line NBN variants may also be at risk for leukemia development, although this is much less characterized. By sequencing 4325 pediatric patients with B-cell acute lymphoblastic leukemia (B-ALL), we systematically examined the frequency of germ line NBN variants and identified 25 unique, putatively damaging NBN coding variants in 50 patients. Compared with the frequency of NBN variants in gnomAD noncancer controls (189 unique, putatively damaging NBN coding variants in 472 of 118 479 individuals), we found significant overrepresentation in pediatric B-ALL (P = .004; odds ratio, 1.8). Most B-ALL-risk variants were missense and cluster within the NBN N-terminal domains. Using 2 functional assays, we verified 14 of 25 variants with severe loss-of-function phenotypes and thus classified these as nonfunctional or partially functional. Finally, we found that germ line NBN variant carriers, all of whom were identified as heterozygous genotypes, showed similar survival outcomes relative to those with wild type status. Taken together, our findings provide novel insights into the genetic predisposition to B-ALL, and the impact of NBN variants on protein function and suggest that heterozygous NBN variant carriers may safely receive B-ALL therapy. These trials were registered at www.clinicaltrials.gov as #NCT01225874, NCT00075725, NCT00103285, NCI-T93-0101D, and NCT00137111.

How I treat long-term survivors of childhood acute leukemia

ABSTRACT

The population of survivors of childhood leukemia who reach adulthood is growing due to improved therapy. However, survivors are at risk of long-term complications. Comprehensive follow-up programs play a key role in childhood leukemia survivor care. The major determinant of long-term complications is the therapeutic burden accumulated over time. Relapse chemotherapy, central nervous system irradiation, hematopoietic stem cell transplantation, and total body irradiation are associated with greater risk of long-term complications. Other parameters include clinical characteristics such as age and sex as well as environmental, genetic, and socioeconomic factors, which can help stratify the risk of long-term complications and organize follow-up program. Early diagnosis improves the management of several late complications such as anthracycline-related cardiomyopathy, secondary cancers, metabolic syndrome, development defects, and infertility. Total body irradiation is the treatment associated with worse long-term toxicity profile with a wide range of complications. Patients treated with chemotherapy alone are at a lower risk of long-term complications, although the optimal long-term follow-up remains unclear. Novel immunotherapies and targeted therapy are generally associated with a better short-term safety profile but still require careful long-term toxicity monitoring. Advances in understanding genetic susceptibility to long-term complications could enable tailored therapeutic strategies for leukemia treatment and optimized follow-up programs.

Blinatumomab for First-Line Treatment of Children and Young Persons With B-ALL

PURPOSE

We tested whether blinatumomab (Blina) is effective as a toxicity-sparing alternative to first-line intensive chemotherapy in children and young persons (CYP) with B-ALL who were chemotherapy-intolerant or chemotherapy-resistant.

METHODS

Data were collected for consecutive CYP (age 1-24 years) with Philadelphia chromosome-positive or Philadelphia chromosome-negative B-ALL who received Blina as first-line therapy. Blina was given as replacement for postremission intensive chemotherapy to patients with chemotherapy intolerance or resistance. Blina responders received further chemotherapy (Blin-CT) or first remission hematopoietic stem-cell transplant (Blin-HSCT) if indicated. Event-free survival (EFS) and overall survival (OS) of the Blin-CT group were compared with those of matched controls treated with standard chemotherapy in the UKALL 2003 trial. Events were defined as death, relapse, or secondary cancer.

RESULTS

From February 2018 to February 2023, 105 patients were treated, of whom 85 were in the Blin-CT group and 20 were in the Blin-HSCT group. A majority of Blin-CT patients received Blina for chemotherapy intolerance (70 of 85, 82%), and the group had a higher-risk profile than unselected patients with B-ALL. Blina was well tolerated with only one patient having a grade 3/4-related toxicity event, and of the 60 patients who were minimal residual disease-positive pre-Blina, 58 of 60 (97%) responded. At a median follow-up of 22 months, the 2-year outcomes of the 80 matched Blin-CT group patients were similar to those of 192 controls (EFS, 95% [95% CI, 85 to 98] v 90% [95% CI, 65 to 93] and OS, 97% [95% CI, 86 to 99] v 94% [95% CI, 89 to 96]). Of the 20 in the HSCT group, three died because of transplant complications and two relapsed.

CONCLUSION

Blina is safe and effective in first-line treatment of chemotherapy-intolerant CYP with ALL.

[Suspicion of constitutional abnormality at diagnosis of childhood leukemia: Update of the leukemia committee of the French Society of Childhood Cancers]

The spectrum of childhood leukemia predisposition syndromes has grown significantly over last decades. These predisposition syndromes mainly involve CEBPA, ETV6, GATA2, IKZF1, PAX5, RUNX1, SAMD9/SAMD9L, TP53, RAS-MAPK pathway, DNA mismatch repair system genes, genes associated with Fanconi anemia, and trisomy 21. The clinico-biological features leading to the suspicion of a leukemia predisposition are highly heterogeneous and require varied exploration strategies. The study of the initial characteristics of childhood leukemias includes high-throughput sequencing techniques, which have increased the frequency of situations where a leukemia predisposing syndrome is suspected. Identification of a leukemia predisposition syndrome can have a major impact on the choice of chemotherapy, the indication for hematopoietic stem cell transplantation, and screening for associated malformations and pathologies. The diagnosis of a predisposition syndrome can also lead to the exploration of family members and genetic counseling. Diagnosis and management should be based on dedicated and multidisciplinary care networks.

Biological Markers of High-Risk Childhood Acute Lymphoblastic Leukemia

Childhood acute lymphoblastic leukemia (ALL) has witnessed substantial improvements in prognosis; however, a subset of patients classified as high-risk continues to face higher rates of relapse and increased mortality. While the National Cancer Institute (NCI) criteria have traditionally guided risk stratification based on initial clinical information, recent advances highlight the pivotal role of biological markers in shaping the prognosis of childhood ALL. This review delves into the emerging understanding of high-risk childhood ALL, focusing on molecular, cytogenetic, and immunophenotypic markers. These markers not only contribute to unraveling the underlying mechanisms of the disease, but also shed light on specific clinical patterns that dictate prognosis. The paradigm shift in treatment strategies, exemplified by the success of tyrosine kinase inhibitors in Philadelphia chromosome-positive leukemia, underscores the importance of recognizing and targeting precise risk factors. Through a comprehensive exploration of high-risk childhood ALL characteristics, this review aims to enhance our comprehension of the disease, offering insights into its molecular landscape and clinical intricacies in the hope of contributing to future targeted and tailored therapies.

The genetic risk of acute lymphoblastic leukemia and its implications for children of Latin American origin

Acute lymphoblastic leukemia (ALL) is the most common cancer in children, and disproportionately affects children of Hispanic/Latino ethnicity in the United States, who have the highest incidence of disease compared with other racial/ethnic groups. Incidence of childhood ALL is similarly high in several Latin American countries, notably in Mexico, and of concern is the rising incidence of childhood ALL in some Hispanic/Latino populations that may further widen this disparity. Prior studies have implicated common germline genetic variants in the increased risk of ALL among Hispanic/Latino children. In this review, we describe the known disparities in ALL incidence as well as patient outcomes that disproportionately affect Hispanic/Latino children across the Americas, and we focus on the role of genetic variation as well as Indigenous American ancestry in the etiology of these disparities. Finally, we discuss future avenues of research to further our understanding of the causes of the disparities in ALL incidence and outcomes in children of Latin American origin, which will be required for future precision prevention efforts.

Germline Variants and Characteristic Features of Hereditary Hematological Malignancy Syndrome

Due to the proliferation of genetic testing, pathogenic germline variants predisposing to hereditary hematological malignancy syndrome (HHMS) have been identified in an increasing number of genes. Consequently, the field of HHMS is gaining recognition among clinicians and scientists worldwide. Patients with germline genetic abnormalities often have poor outcomes and are candidates for allogeneic hematopoietic stem cell transplantation (HSCT). However, HSCT using blood from a related donor should be carefully considered because of the risk that the patient may inherit a pathogenic variant. At present, we now face the challenge of incorporating these advances into clinical practice for patients with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) and optimizing the management and surveillance of patients and asymptomatic carriers, with the limitation that evidence-based guidelines are often inadequate. The 2016 revision of the WHO classification added a new section on myeloid malignant neoplasms, including MDS and AML with germline predisposition. The main syndromes can be classified into three groups. Those without pre-existing disease or organ dysfunction; DDX41, TP53, CEBPA, those with pre-existing platelet disorders; ANKRD26, ETV6, RUNX1, and those with other organ dysfunctions; SAMD9/SAMD9L, GATA2, and inherited bone marrow failure syndromes. In this review, we will outline the role of the genes involved in HHMS in order to clarify our understanding of HHMS.

Diagnostic work-up of hematological malignancies with underlying germline predisposition disorders (GPD)

Hematological malignancies with underlying germline predisposition disorders have been recognized by the World Health Organization 5th edition and International Consensus Classification (ICC) classification systems. The list of genes and the associated phenotypes are expanding and involve both pediatric and adult populations. While the clinical presentation and underlying molecular pathogenesis are relatively well described, the knowledge regarding the bone marrow morphologic features, the landscape of somatic aberrations associated with progression to hematological malignancies is limited. These pose challenges in the diagnosis of low-grade myelodysplastic syndrome (MDS) to hematopathologists which carries direct implication for various aspects of clinical management of the patient, donor selection for transplantation, and family members. Here in, we provide a focused review on the diagnostic work-up of hematological malignancies with underlying germline predisposition disorders with emphasis on the spectrum of hematological malignancies associated with each entity, and characteristic bone marrow morphologic, somatic cytogenetic and molecular alterations at the time of diagnosis of hematological malignancies. We also review the key clinical, morphologic, and molecular features, that should initiate screening for these entities.

Accurate interpretation of p53 immunohistochemical patterns is a surrogate biomarker for TP53 alterations in large B-cell lymphoma

BACKGROUND

To clarify the relationship between p53 immunohistochemistry (IHC) staining and TP53 alterations (including mutations and deletions) in large B-cell lymphomas (LBCLs) and to explore the possibility of p53 IHC expression patterns as surrogate markers for TP53 alterations.

METHODS

A total of 95 patients diagnosed with LBCLs were selected, and paraffin samples were taken for TP53 gene sequencing, fluorescence in situ hybridization and p53 IHC staining. The results were interpreted by experienced pathologists and molecular pathologists.

RESULTS

Forty-three nonsynonymous TP53 mutations and p53 deletions were detected in 40 cases, whereas the remaining 55 cases had wild-type TP53 genes. The majority of TP53 mutations (34/43, 79.1%) occurred in exons 4-8, and R248Q was the most common mutation codon (4/43, 9.3%). The highest frequency single nucleotide variant was C > T (43.6%). p53 expression was interpreted as follows: Pattern A: p53 staining was positive in 0%-3% of tumor cells, Pattern B: p53 staining was positive in 4-65% of tumor cells, Pattern C: more than 65% of tumor cells were stained positive for p53. The p53 IHC expression patterns were associated with TP53 alterations. Gain of function variants and wild-type TP53 tended to exhibit type C and B p53 expression patterns, but loss of function variants were exclusively seen in type A cases. Additionally, interpretation of the staining by various observers produced significant reproducibility.

CONCLUSIONS

The p53 IHC expression patterns can be used to predict TP53 alterations and are reliable for diverse alteration types, making them possible surrogate biomarkers for TP53 alterations in LBCLs.

Genes of Predisposition to Childhood Beta-Cell Acute Lymphoblastic Leukemia in the Kazakh Population

BACKGROUND

Today, acute lymphoblastic leukemia is one of the most common malignant diseases of the hematopoietic system. The genetic predisposition to ALL is not fully explored in various ethnic populations.

OBJECTIVE

The study aimed to conduct a comparative analysis of the population frequencies of alleles and genotypes of polymorphic gene variants: immune regulation GATA3 (rs3824662); transcription and differentiation of B cells: ARID5B (rs7089424, rs10740055), IKZF1 (rs4132601); differentiation of hematopoietic cells: PIP4K2A (rs7088318); apoptosis: CEBPE (rs2239633), tumor suppressors: CDKN2A (rs3731249), TP53 (rs1042522); carcinogen metabolism: CBR3 (rs1056892), CYP1A1 (rs104894, rs4646903), according to genome-wide association studies analyses associated with the risk of developing pediatric beta-cell acute lymphoblastic leukemia (B-cell ALL), in an ethnically homogeneous population of Kazakhs with studied populations.

METHODS

The genomic database consists of 1800 conditionally healthy persons of Kazakh nationality, genotyped using OmniChip 2.5-8 Illumina chips at the deCODE genetics as part of the InterPregGen 7 project of the European Union (EU) framework program under Grant Agreement No. 282540.

RESULTS

High population frequencies of single nucleotide polymorphism (SNP) minor alleles identified for immune regulation genes - GATA3 rs3824662 - 42.5%; transcription and differentiation of B-cells genes - ARID5B rs7089424 - 33.1% and rs10740055 - 48.5%, which suggests their significant genetic contribution to the risk of development and prognosis of the effectiveness of B-cell ALL therapy in the Kazakh population. The significantly lower population frequency of the minor allele G rs1056892 CBR3 gene - 38.6% in the Kazakhs suggests its significant protective effect in reducing the risk of childhood B-cell ALL and the smaller number of cardiac complications after anthracycline therapy.

CONCLUSION

The obtained results will serve as a basis for developing effective methods for predicting the risk of development, early diagnosis, and effectiveness of treatment of B-cell ALL in children.

Germline Genetic NBN Variation and Predisposition to B-cell Acute Lymphoblastic Leukemia in Children

Biallelic mutation in the DNA-damage repair gene NBN is the genetic cause of Nijmegen Breakage Syndrome, which is associated with predisposition to lymphoid malignancies. Heterozygous carriers of germline NBN variants may also be at risk for leukemia development, although this is much less characterized. We systematically examined the frequency of germline NBN variants in pediatric B-ALL and identified 25 putatively damaging NBN coding variants in 50 of 4,183 B-ALL patients. Compared with the frequency of NBN variants in 118,479 gnomAD non-cancer controls we found significant overrepresentation in pediatric B-ALL (p=0.004, OR=1.77). Most B-ALL-risk variants were missense and cluster within the NBN N-terminal domains. Using two functional assays, we verified 14 of 25 variants with severe loss-of-function phenotypes and thus classified these as pathogenic or likely pathogenic. Finally, we found that heterozygous germline NBN variant carriers showed similar survival outcomes relative to those with WT status. Taken together, our findings provide novel insights into the genetic predisposition to B-ALL, the impact of NBN variants on protein function and suggest that heterozygous NBN variant carriers may safely receive B-ALL therapy.

The Effect of the Persian Gulf Jellyfish (Cassiopea andromeda) Venom on the Expression of P15, P21, P53, DNMT1, and Bcl-2 in Acute Lymphoblastic Leukemia Jurkat Cells

Background: One of the acute hematologic malignancies is acute lymphoblastic leukemia (ALL), which is formed in B or T lymphocyte stem cells. Regarding the increasing tendency to herbal and marine studies and unclear characteristics of Cassiopea andromeda Venom, this study was performed to determine its effects on Jurkat cells as a model for T-ALL. Materials and Methods: In this experimental study, the cells were treated with a variety of concentrations of Cassiopea andromeda venom at different periods and times. Growth inhibition and toxic effects of Cassiopea andromeda Venom were evaluated by methyl thiazole tetrazolium salt reduction (MTT test). The flow cytometry analysis was carried out using 7-aminoactinomycin D (7AAD) and Annexin V stains to evaluate the venom's effect on apoptotic pathways. Besides, Real-Time PCR was performed to evaluate the relative gene expression. Results: Cassiopea andromeda venom inhibited the growth of Jurkat cells in a concentration and time manner. Jurkat cell growth was inhibited by 48.9% after 72 hours of treatment with 250µg/mL Cassiopea andromeda venom. The venom increased the apoptotic process through the upregulation of p15INK4b and P53 proteins and downregulation of Bcl-2, p21 WAF1/CIP1, and DNMT1 in the Jurkat cell line. Conclusion: Considering the growth inhibitory property of Cassiopea andromeda Venom, we recommend it as a part of combinational medication for treating ALL in animal trials and for other leukemias in vitro studies.

Prevalence of pathogenic variants in cancer-predisposing genes in second cancer after childhood solid cancers

BACKGROUND

Second malignant neoplasms (SMNs) are one of the most severe late complications after pediatric cancer treatment. However, the effect of genetic variation on SMNs remains unclear. In this study, we revealed germline genetic factors that contribute to the development of SMNs after treatment of pediatric solid tumors.

METHODS

We performed whole-exome sequencing in 14 pediatric patients with SMNs, including three brain tumors.

RESULTS

Our analysis revealed that five of 14 (35.7%) patients had pathogenic germline variants in cancer-predisposing genes (CPGs), which was significantly higher than in the control cohort (p < 0.01). The identified genes with variants were TP53 (n = 2), DICER1 (n = 1), PMS2 (n = 1), and PTCH1 (n = 1). In terms of the type of subsequent cancer, leukemia and multiple episodes of SMN had an exceptionally high rate of CPG pathogenic variants. None of the patients with germline variants had a family history of SMN development. Mutational signature analysis showed that platinum drugs contributed to the development of SMN in three cases, which suggests the role of platinum agents in SMN development.

CONCLUSIONS

We highlight that overlapping effects of genetic background and primary cancer treatment contribute to the development of second cancers after treatment of pediatric solid tumors. A comprehensive analysis of germline and tumor samples may be useful to predict the risk of secondary cancers.

Recent progress in pediatric lymphoblastic leukemia

The probability of long-term survival for children with lymphoblastic leukemia has improved dramatically over recent decades, mainly owing to advances in genomic analysis techniques, which have improved our understanding of the nature of leukemic cells and prognostic prediction based on the evaluation of precise treatment response. Risk-adjusted chemotherapy based on these advances has simultaneously reduced relapse rates and minimized complications. In addition, recent genomic analyses have deepened our understanding of the pathogenesis of leukemia and revealed the involvement of germline variations in the clinical course of leukemia treatment. Additionally, advances in minimal residual disease assays and the introduction of immunotherapy are expected to further improve therapeutic analyses. Further advances in clinical and translational research are anticipated to improve survival to 100% in a healthy state.

Coincidence of primary adrenocortical carcinoma and melanoma: three CASE reports

BACKGROUND

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with a heterogeneous prognosis, while adrenal metastasis from other primary cancers, including melanoma, may occur more frequently. ACC may rarely occur as part of familial cancer syndromes, but even in sporadic cases, a significant proportion of patients had other malignancies before or after diagnosis of ACC. Herein we present three cases where sporadic ACC was identified in patients with coexistent or previous history of melanoma.

CASE DESCRIPTION

Patient 1 - A 37-yr-old man with a superficial spreading BRAF-positive melanoma was found to harbour a progressively growing left adrenal mass. Initially, he was suspected of having adrenal metastasis, but the histology after adrenalectomy confirmed ACC. Patient 2 - A 68-year-old man with a history of recurrent BRAF-positive melanoma was diagnosed with disseminated metastatic melanoma recurrence, including a rapidly enlarging left adrenal mass. Consequently, he underwent left adrenalectomy, and histology again confirmed ACC. Patient 3 - A 50-yr-old man was referred with histological diagnosis of metastatic ACC. He had a background history of pT1 melanoma. We undertook targeted sequencing of ACC tissue samples in all cases. Somatic variants were observed in the known driver genes CTNNB1 (Patient 1), APC and KMT2D (Patient 2), and APC and TP53 (Patient 3). Germline TP53 variants (Li-Fraumeni syndrome) were excluded in all cases. Retrospective review of our patient cohort in the last 21 years revealed a frequency of 0.5% of histologically diagnosed melanoma metastasis among patients referred for adrenal masses. On the other hand, 1.6% of patients with histologically confirmed ACC had a previous history of melanoma.

CONCLUSION

Sporadic ACC can occur in the background of melanoma, even if adrenal metastasis might appear to be the most likely diagnosis. Coexistent primary adrenal malignancy should be considered and investigated for in all patients with a history of melanoma with suspicious adrenal lesions.

Safety and Efficacy of Humanized Versus Murinized CD19 and CD22 CAR T-Cell Cocktail Therapy for Refractory/Relapsed B-Cell Lymphoma

CD19 chimeric antigen receptor T-cell (CAR-T) therapy is efficacious for refractory/relapsed (R/R) B-cell hematological malignancies, yet relapse due to CD19 antigen escape remains a challenge. Our trial explored simultaneous targeting of multiple B-cell antigens as a therapeutic approach that may reduce the risk of relapse. We tested the safety and efficacy of CAR19/22 T-cell cocktail therapy including murinized and humanized products among patients with R/R aggressive B-cell lymphoma. In the group that received the humanized product, 11/12 (91.7%) patients achieved an objective response, including 9/12 (75%) complete responses (CRs) by day 28. The overall response rate and CR rate in the murinized group was 92.9% (13/14) and 42.9% (6/14), respectively. Nine of 12 (75%) patients in the humanized group maintained CR at month 3 following infusion, compared to 5/14 patients (35.7%) in the murinized group. Progression-free survival (PFS) was more favorable in the humanized compared to the murinized group. Most patients had mild cytokine release syndrome (CRS) (grade 1-2) in both groups. This study demonstrates that CAR19/22 T-cell cocktail therapy is safe and effective for R/R B-cell lymphoma and that patients treated with a humanized CAR-T exhibited better efficacy compared to patients treated with a murinized CAR-T therapy.

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.

Molecular Diagnostic Testing for Hematopoietic Neoplasms: Linking Pathogenic Drivers to Personalized Diagnosis

Molecular diagnostics inhabit an increasingly central role in characterizing hematopoietic malignancies. This brief review summarizes the genomic targets important for many major categories of hematopoietic neoplasia by focusing on disease pathogenesis. In myeloid disease, recurrent mutations in key functional classes drive clonal hematopoiesis, on which additional variants can specify clinical presentation and accelerate progression. Lymphoblastic leukemias are frequently initiated by oncogenic fusions that block lymphoid maturation while, in concert with additional mutations, driving proliferation. The links between genetic aberrations and lymphoma patient outcomes have been clarified substantially through the clustering of genomic profiles. Finally, the addition of next-generation sequencing strategies to cytogenetics is refining risk stratification for plasma cell myeloma. In all categories, molecular diagnostics shed light on the unique mechanistic underpinnings of each individual malignancy, thereby empowering more rational, personalized care for these patients.

Association of TP53 rs1042522 C>G Polymorphism with Glioma Risk in Chinese Children

Glioma is the most common intracranial malignancy. TP53 is a crucial tumor suppressor gene that plays an essential regulatory role in cell growth, apoptosis, and DNA repair. The TP53 rs1042522 C>G polymorphism has been reported to be strongly associated with various tumor risks. To assess the TP53 rs1042522 C>G polymorphism with glioma risk in Chinese children, we determined the genotypes of the TP53 rs1042522 C>G polymorphism in 171 glioma patients and 228 cancer-free controls by Taqman assay. We assessed the association of the polymorphism with glioma risk using odds ratio (OR) and 95% confidence interval (CI) generated by logistic regression models. We also performed stratified analyses by age, gender, tumor subtypes, and clinical stages, but no significant association was detected between TP53 rs1042522 C>G polymorphism and childhood glioma risk. These results suggest that the TP53 rs1042522 C>G polymorphism is not associated with glioma risk in Chinese children. Subsequent studies with a larger sample size are needed to validate our results.

Evolution of germline TP53 variant classification in children with cancer

Li-Fraumeni syndrome, caused by germline pathogenic variants in TP53, results in susceptibility to multiple cancers. Variants of uncertain significance (VUS) and reclassification of variants over time pose management concerns given improved survival with cancer surveillance for LFS patients. We describe the experience of TP53 variant reclassification at a pediatric cancer center.

METHODS

We reviewed medical records (2010-2019) of 756 patients seen in Texas Children's Cancer Genetics Clinic. We noted initial TP53 classification and any reclassifications. We then classified TP53 variants following ClinGen TP53 variant curation expert panel recommendations using data from ClinVar, medical literature and IARC database.

RESULTS

Of 234 patients tested for TP53, 27 (11.5%) reports contained pathogenic/likely pathogenic (P/LP) variants and 7 (3)% contained VUS. By January 2022, 4 of 6 unique VUS and 2 of 16 unique P/LP variants changed interpretations in ClinVar. Reinterpretation of these 4 VUS in ClinVar matched clinical decision at the time of initial report. Applying TP53 VCEP specifications classified 3 VUS to P/LP/benign, and one pathogenic variant to likely benign.

CONCLUSIONS

Planned review of variant significance is essential, especially for patients with high probability of LFS.

Consensus Recommendations for the Clinical Management of Hematological Malignancies in Patients with DNA Double Stranded Break Disorders

Patients with double stranded DNA repair disorders (DNARDs) (Ataxia Telangiectasia (AT) and Nijmegen Breakage syndrome (NBS)) are at a very high risk for developing hematological malignancies in the first two decades of life. The most common neoplasms are T-cell lymphoblastic malignancies (T-cell ALL and T-cell LBL) and diffuse large B cell lymphoma (DLBCL). Treatment of these patients is challenging due to severe complications of the repair disorder itself (e.g., congenital defects, progressive movement disorders, immunological disturbances and progressive lung disease) and excessive toxicity resulting from chemotherapeutic treatment. Frequent complications during treatment for malignancies are deterioration of pre-existing lung disease, neurological complications, severe mucositis, life threating infections and feeding difficulties leading to significant malnutrition. These complications make modifications to commonly used treatment protocols necessary in almost all patients. Considering the rarity of DNARDs it is difficult for individual physicians to obtain sufficient experience in treating these vulnerable patients. Therefore, a team of experts assembled all available knowledge and translated this information into best available evidence-based treatment recommendations.

Outcome of aggressive B-cell lymphoma with TP53 alterations administered with CAR T-cell cocktail alone or in combination with ASCT

TP53 gene alteration confers inferior prognosis in refractory/relapse aggressive B-cell non-Hodgkin lymphoma (r/r B-NHL). From September 2016 to September 2020, 257 r/r B-NHL patients were assessed for eligibility for two trials in our center, assessing anti-CD19 and anti-CD22 chimeric antigen receptor (CAR19/22) T-cell cocktail treatment alone or in combination with autologous stem cell transplantation (ASCT). TP53 alterations were screened in 123 enrolled patients and confirmed in 60. CAR19/22 T-cell administration resulted in best objective (ORR) and complete (CRR) response rate of 87.1% and 45.2% in patients with TP53 alterations, respectively. Following a median follow-up of 16.7 months, median progression-free survival (PFS) was 14.8 months, and 24-month overall survival (OS) was estimated at 56.3%. Comparable ORR, PFS, and OS were determined in individuals with or without TP53 alterations, and in individuals at different risk levels based on functional stratification of TP53 alterations. CAR19/22 T-cell treatment in combination with ASCT resulted in higher ORR, CRR, PFS, and OS, but reduced occurrence of severe CRS in this patient population, even in individuals showing stable or progressive disease before transplantation. The best ORR and CRR in patients with TP53 alterations were 92.9% and 82.1%, respectively. Following a median follow-up of 21.2 months, 24-month PFS and OS rates in patients with TP53 alterations were estimated at 77.5% and 89.3%, respectively. In multivariable analysis, this combination strategy predicted improved OS. In conclusion, CAR19/22 T-cell therapy is efficacious in r/r aggressive B-NHL with TP53 alterations. Combining CAR-T cell administration with ASCT further improves long-term outcome of these patients.

The clinical characteristics and prognosis in adult Ph negative acute lymphoblastic leukemia with TP53 aberrations

Very few reports elucidate the prognosis of patients with TP53 aberrations using both measurable residual disease (MRD) and the status of having undergone allogeneic hematopoietic stem cell transplantation (allo-SCT). In this study, aberrations of TP53 were analyzed using next-generation sequencing (NGS) and fluorescence in situ hybridization (FISH) in patients with Philadelphia chromosome-negative (Ph^-) ALL enrolled in a prospective single-arm clinical trial at our leukemia center. We analyzed the survival of the patients grouped according to the MRD level at the third month and whether or not received allo-SCT. We found that allo-SCT could improve the OS in patients with TP53 aberrations; Patients having negative MRD at the third month still showed worse 3-year OS and 3-year DFS without undergoing allo-SCT, which is different from previous studies, moreover, the prognostic significance of TP53 deletions was as important as TP53 mutations, the importance of screening both TP53 deletions and mutations in adult Ph^- ALL at diagnosis should be emphasized.

In Utero Development and Immunosurveillance of B Cell Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most frequent type of pediatric cancer with a peak incidence at 2–5 years of age. ALL frequently begins in utero with the emergence of clinically silent, preleukemic cells. Underlying leukemia-predisposing germline and acquired somatic mutations define distinct ALL subtypes that vary dramatically in treatment outcomes. In addition to genetic predisposition, a second hit, which usually occurs postnatally, is required for development of overt leukemia in most ALL subtypes. An untrained, dysregulated immune response, possibly due to an abnormal response to infection, may be an important co-factor triggering the onset of leukemia. Furthermore, the involvement of natural killer (NK) cells and T helper (Th) cells in controlling the preleukemic cells has been discussed. Identifying the cell of origin of the preleukemia-initiating event might give additional insights into potential options for prevention. Modulation of the immune system to achieve prolonged immunosurveillance of the preleukemic clone that eventually dies out in later years might present a future directive. Herein, we review the concepts of prenatal origin as well as potential preventive approaches to pediatric B cell precursor (BCP) ALL.

TP53 Expression and Mutational Analysis in Hematological Malignancy in Jeddah, Saudi Arabia

Background: Tumor protein 53 (TP53) is a tumor-suppressor gene and plays an essential role in apoptosis, cell cycle arrest, genomic stability, and DNA repair. Although it is the most often mutated gene in human cancer, it has respectively low frequency in hematological malignancy but is significantly linked with complex karyotype, poor prognosis, and chemotherapeutic response. Nevertheless, the prevalence and prognostic role of TP53 mutations in hematological malignancy in Saudi patients are not well reported. We, therefore, aim to assess the frequency of TP53 mutations in hematological malignancies in Saudi Arabia. Method: 20 different hematological malignancy samples were tested using fluorescence in situ hybridization (FISH) technique for TP53 deletion detection and next-generation sequencing (NGS) targeted panel was applied on 10 samples for mutations identification specifically TP53 mutation. Results: TP53 deletion was detected in 6 of 20 samples by FISH. Most of the 6 patients with TP53 deletion had acute lymphoblastic leukemia (ALL), and majority of them were child. NGS result revealed one heterozygous missense mutation in exon 5 of the TP53 gene (c. G9963A, p.H175R). Conclusion: To the best of our knowledge, the TP53 mutation is novel variant, and the first time we are reporting their association with myelodysplastic syndromic individual with complex karyotype. This study recommends further analysis of genomic mutations on bigger cohorts, utilizing high throughput technologies.

Population-Based Newborn Screening for Germline TP53 Variants: Clinical Benefits, Cost-Effectiveness, and Value of Further Research

BACKGROUND

Identification of children and infants with Li-Fraumeni syndrome prompts tumor surveillance and allows potential early cancer detection. We assessed the clinical benefits and cost-effectiveness of population-wide newborn screening for TP53 variants (TP53-NBS).

METHODS

We simulated the impact of TP53-NBS using data regarding TP53-associated pediatric cancers and pathogenic or likely pathogenic (P/LP) TP53 variants from Surveillance, Epidemiology, and End Results; ClinVar and gnomAD; and clinical studies. We simulated an annual US birth cohort under usual care and TP53-NBS and estimated clinical benefits, life-years, and costs associated with usual care and TP53-NBS.

RESULTS

Under usual care, of 4 million newborns, 608 (uncertainty interval [UI] = 581-636) individuals would develop TP53-associated cancers before age 20 years. Under TP53-NBS, 894 individuals would have P/LP TP53 variants detected. These individuals would undergo routine surveillance after detection of P/LP TP53 variants decreasing the number of cancer-related deaths by 7.2% (UI = 4.0%-12.1%) overall via early malignancy detection. Compared with usual care, TP53-NBS had an incremental cost-effectiveness ratio of $106 009 per life-year gained. Probabilistic analysis estimated a 40% probability that TP53-NBS would be cost-effective given a $100 000 per life-year gained willingness-to-pay threshold. Using this threshold, a value of information analysis found that additional research on the prevalence of TP53 variants among rhabdomyosarcoma cases would resolve most of the decision uncertainty, resulting in an expected benefit of 349 life-years gained (or $36.6 million).

CONCLUSIONS

We found that TP53-NBS could be cost-effective; however, our findings suggest that further research is needed to reduce the uncertainty in the potential health outcomes and costs associated with TP53-NBS.

[Mutational spectrum and its prognostic significance in childhood acute lymphoblastic leukemia based on next-generation sequencing technology]

Objective: This study analyzed the correlation between genetic mutation and prognostic significance in childhood acute lymphoblastic leukemia (ALL) . Methods: Targeted exome by next-generation sequencing (NGS) technology was used to carry out molecular profiling of untreated 141 children with ALL in Fujian Medical University Union Hospital from November 2016 to December 2019. Correlation of genetic features and clinical features and outcomes was analyzed. Results: Among the 141 pediatric patients with ALL, 160 somatic mutations were detected in 83 patients (58.9% ) , including 37 grade Ⅰ mutations and 123 grade Ⅱ mutations. Single nucleotide variation was the most common type of mutation. KRAS was the most common mutant gene (12.5% ) , followed by NOTCH1 (11.9% ) , and NRAS (10.6% ) . RAS pathway (KRAS, FLT3, PTPN11) , PAX5 and TP53 mutations were only detected, and NRAS mutations was mainly found in B-ALL while FBXW7 and PTEN mutations were only found, and NOTCH1 mutation was mainly detected in T-ALL. The average number of mutations detected in each child with T-ALL was significantly higher than in children with B-ALL (4.16±1.33 vs 2.04±0.92, P=0.004) . The children were divided into mutation and non-mutation groups according to the presence or absence of genetic variation. There were no statistically significant differences in sex, age, newly diagnosed white blood cell count, minimal or measurable residual disease monitoring results, expected 3-year event-free survival (EFS) and overall survival (OS) between the two groups (P>0.05) . On the other hand, the proportion of T-ALL and fusion gene negative children in the mutant group was significantly higher than the non-mutation group (P=0.021 and 0.000, respectively) . Among the patients without fusion gene, the EFS of children with grade I mutation was significantly lower than children without grade I mutation (85.5% vs 100.0% , P=0.039) . Among children with B-ALL, the EFS of those with TP53 mutation was significantly lower than those without TP53 mutation (37.5% vs 91.2% , P<0.001) . Conclusion: Genetic variation is more common in childhood ALL and has a certain correlation with clinical phenotype and prognosis. Therefore, targeted exome by NGS can be used as an important supplement to the traditional morphology, immunology, cytogenetics, and molecular biology classification.

Antibiotics in early life and childhood pre-B-ALL. Reasons to analyze a possible new piece in the puzzle

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer with precursor B-cell ALL (pB-ALL) accounting for ~ 85% of the cases. Childhood pB-ALL development is influenced by genetic susceptibility and host immune responses. The role of the intestinal microbiome in leukemogenesis is gaining increasing attention since Vicente-Dueñas' seminal work demonstrated that the gut microbiome is distinct in mice genetically predisposed to ALL and that the alteration of this microbiome by antibiotics is able to trigger pB-ALL in Pax5 heterozygous mice in the absence of infectious stimuli. In this review we provide an overview on novel insights on the role of the microbiome in normal and preleukemic hematopoiesis, inflammation, the effect of dysbiosis on hematopoietic stem cells and the emerging importance of the innate immune responses in the conversion from preleukemic to leukemic state in childhood ALL. Since antibiotics, which represent one of the most widely used medical interventions, alter the gut microbial composition and can cause a state of dysbiosis, this raises exciting epidemiological questions regarding the implications for antibiotic use in early life, especially in infants with a a preleukemic "first hit". Sheading light through a rigorous study on this piece of the puzzle may have broad implications for clinical practice.

Landscape of germline cancer predisposition mutations testing and management in pediatrics: Implications for research and clinical care

As germline genetic testing capacities have improved over the last two decades, increasingly more people are newly diagnosed with germline cancer susceptibility mutations. In the wake of this growth, there remain limitations in both testing strategies and translation of these results into morbidity- and mortality-reducing practices, with pediatric populations remaining especially vulnerable. To face the challenges evoked by an expanding diversity of germline cancer mutations, we can draw upon a model cancer-associated genetic condition for which we have developed a breadth of expertise in managing, Trisomy 21. We can additionally apply advances in other disciplines, such as oncofertility and pharmacogenomics, to enhance care delivery. Herein, we describe the history of germline mutation testing, epidemiology of known germline cancer mutations and their associations with childhood cancer, testing limitations, and future directions for research and clinical care.

Therapy-related Myeloid Neoplasms in Children: A Single-institute Study

Therapy-related myeloid neoplasm (t-MN) in the pediatric population is not well characterized. We studied 12 pediatric patients diagnosed with t-MN in our institution since 2006. The median age at the t-MN diagnoses was 14.8 years (range, 9 to 20 y). The primary malignancies included 9 solid tumors and 3 hematopoietic malignancies. Rhabdomyosarcoma (n=4) was the most common primary malignancy. Five of the 9 patients with solid tumors and all 3 patients with hematopoietic malignancies had primary neoplasms involving bone marrow. The median latency period was 5.2 years (range, 1.8 to 13.8 y). Thrombocytopenia was present in all patients at the t-MN diagnoses. Complete or partial monosomy of chromosome 5 or 7 were the 2 most common cytogenetic abnormalities. A quarter of patients demonstrated a genetic predisposition to t-MN: 1 with Li-Fraumeni syndrome with a germline TP53 R248Q mutation, 1 with Noonan syndrome with a somatic mutation (PTPN11 S502T), and 1 with a constitutive chromosomal translocation [t(X;9)(p22;q34)] and a germline TP53 L130V mutation. Outcomes remain poor. Two patients survived 3 and 5.1 years after hematopoietic stem cell transplantation.

NUDT15 variants confer high incidence of second malignancies in children with acute lymphoblastic leukemia

The effect of genetic variation on second malignant neoplasms (SMNs) remains unclear. First, we identified the pathogenic germline variants in cancer-predisposing genes among 15 children with SMNs after childhood leukemia/lymphoma using whole-exome sequencing. Because the prevalence was low, we focused on the association between SMNs and NUDT15 in primary acute lymphoblastic leukemia (ALL) cases. NUDT15 is one of the 6-mercaptopurine (6-MP) metabolic genes, and its variants are common in East Asian individuals. The prevalence of NUDT15 hypomorphic variants was higher in patients with SMNs (n = 14; 42.9%) than in the general population in the gnomAD database (19.7%; P = .042). In the validation study with a cohort of 438 unselected patients with ALL, the cumulative incidence of SMNs was significantly higher among those with (3.0%; 95% confidence interval [CI], 0.6% to 9.4%) than among those without NUDT15 variants (0.3%; 95% CI, 0.0% to 1.5%; P = .045). The 6-MP dose administered to patients with ALL with a NUDT15 variant was higher than that given to those without SMNs (P = .045). The 6-MP-related mutational signature was observed in SMN specimens after 6-MP exposure. In cells exposed to 6-MP, a higher level of 6-MP induced DNA damage in NUDT15-knockdown induced pluripotent stem cells. Our study indicates that NUDT15 variants may confer a risk of SMNs after treatment with 6-MP in patients with ALL.

Recent Advances in Pediatric Cancer Research

Over the past few years, the field of pediatric cancer has experienced a shift in momentum, and this has led to new and exciting findings that have relevance beyond pediatric malignancies. Here we present the current status of key aspects of pediatric cancer research. We have focused on genetic and epigenetic drivers of disease, cellular origins of different pediatric cancers, disease models, the tumor microenvironment, and cellular immunotherapies.

Toward prevention of childhood ALL by early-life immune training

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is the most common form of childhood cancer. Chemotherapy is associated with life-long health sequelae and fails in ∼20% of cases. Thus, prevention of leukemia would be preferable to treatment. Childhood leukemia frequently starts before birth, during fetal hematopoiesis. A first genetic hit (eg, the ETV6-RUNX1 gene fusion) leads to the expansion of preleukemic B-cell clones, which are detectable in healthy newborn cord blood (up to 5%). These preleukemic clones give rise to clinically overt leukemia in only ∼0.2% of carriers. Experimental evidence suggests that a major driver of conversion from the preleukemic to the leukemic state is exposure to immune challenges. Novel insights have shed light on immune host responses and how they shape the complex interplay between (1) inherited or acquired genetic predispositions, (2) exposure to infection, and (3) abnormal cytokine release from immunologically untrained cells. Here, we integrate the recently emerging concept of "trained immunity" into existing models of childhood BCP-ALL and suggest future avenues toward leukemia prevention.

Clinical and Functional Significance of TP53 Exon 4-Intron 4 Splice Junction Variants

Germline TP53 splicing variants are uncommon, and their clinical relevance is unknown. However, splice-altering variants at exon 4-intron 4 junctions are relatively enriched in pediatric adrenocortical tumors (ACT). Nevertheless, family histories of cancer compatible with classic Li-Fraumeni syndrome are rarely seen in these patients. We used conventional and in silico assays to determine protein stability, splicing, and transcriptional activity of 10 TP53 variants at exon 4-intron 4 junctions and analyzed their clinical correlates. We reviewed public databases that report the impact of TP53 variants in human cancer and examined individual reports, focusing on family history of cancer. TP53 exon 4-intron 4 junction germline variants were identified in 9 of 75 pediatric ACTs enrolled in the International Pediatric Adrenocortical Tumor Registry and Children's Oncology Group ARAR0332 study. An additional eight independent TP53 variants involving exon 4 splicing were identified in the Pediatric Cancer Genome Project (n = 5,213). These variants resulted in improper expression due to ineffective splicing, protein instability, altered subcellular localization, and loss of function. Clinical case review of carriers of TP53 exon 4-intron 4 junction variants revealed a high incidence of pediatric ACTs and atypical tumor types not consistent with classic Li-Fraumeni syndrome. Germline variants involving TP53 exon 4-intron 4 junctions are frequent in ACT and rare in other pediatric tumors. The collective impact of these germline TP53 variants on the fidelity of splicing, protein structure, and function must be considered in evaluating cancer susceptibility. IMPLICATIONS: Taken together, the data indicate that splice variants at TP53 codon 125 and surrounding bases differentially impacted p53 gene expression and function.

Long-Term Effects of Pediatric Acute Lymphoblastic Leukemia Chemotherapy: Can Recent Findings Inform Old Strategies?

During the last few decades, pediatric acute lymphoblastic leukemia (ALL) cure rates have improved significantly with rates exceeding 90%. Parallel to this remarkable improvement, there has been mounting interest in the long-term health of the survivors. Consequently, modified treatment protocols have been developed and resulted in the reduction of many adverse long-term consequences. Nevertheless, these are still substantial concerns that warrant further mitigation efforts. In the current review, pediatric-ALL survivors' late adverse events, including secondary malignant neoplasms (SMNs), cardiac toxicity, neurotoxicity, bone toxicity, hepatic dysfunction, visual changes, obesity, impact on fertility, and neurocognitive effects have been evaluated. Throughout this review, we attempted to answer a fundamental question: can the recent molecular findings mitigate pediatric-ALL chemotherapy's long-term sequelae on adult survivors? For SMNs, few genetic predisposition factors have been identified including TP53 and POT1 variants. Other treatment-related risk factors have been identified such as anthracyclines' possible association with breast cancer in female survivors. Cardiotoxicity is another significant and common adverse event with some germline variants been found, albeit with conflicting evidence, to increase the risk of cardiac toxicity. For peripheral neurotoxicity, vincristine is the primary neurotoxic agent in ALL regimens. Some germline genetic variants were found to be associated with the vincristine neurotoxic effect's vulnerability. However, these were mainly detected with acute neuropathy. Moreover, the high steroid doses and prolonged use increase bone toxicity and obesity risk with some pharmacogenetic biomarkers were associated with increased steroid sensitivity. Therefore, the role of these biomarkers in tailoring steroid choice and dose is a promising research area. Future directions in pediatric ALL treatment should consider the various opportunities provided by genomic medicine. Understanding the molecular bases underlying toxicities will classify patients into risk groups and implement a closer follow-up to those at higher risk. Pharmacogenetic-guided dosing and selecting between alternative agents have proven their efficacy in the short-term management of childhood ALL. It is the right time to think about a similar approach for the life-long consequences on survivors.