Novel RUNX1 Variation in B-cell Acute Lymphoblastic Leukemia.

Acute lymphoblastic leukemia (ALL) is a malignant disease of hematopoietic stem cells. B cell ALL (B-ALL) is characterized by highly proliferative and poorly differentiated progenitor B cells in the bone marrow. Chromosomal rearrangements, aberrant cell signaling, and mutations lead to dysregulated cell cycle and clonal proliferation of abnormal B cell progenitors. In this study, we aimed to examine hot spot genetic variations in the RUNX1, IDH2, and IL2RA genes in a group of (n=52) pediatric B-ALL. Sanger sequencing results revealed a rare RUNX1 variant p.Leu148Gln in one B-ALL patient with disease recurrence. Additionally, common intronic variations rs12358961 and rs11256369 of IL2RA were determined in two patients. None of the patients had the IDH2 variant. RUNX1, IDH2, and IL2RA variations were rare events in ALL. This study detected a novel pathogenic RUNX1 variation in a patient with a poor prognosis. Examining prognostically important genetic anomalies of childhood lymphoblastic leukemia patients and the signaling pathway components will pilot more accurate prognosis estimations.

Impact of TP53 gene variants on prognosis and survival of childhood acute lymphoblastic leukemia.

The tumor suppressor protein 53 (TP53) gene is one of the most studied genes in cancer. Although TP53 variants are rare events in acute leukemia, recent observations showed that relapse samples might harbor TP53 variants. Here, we aimed to determine TP53 variants (hotspot region, exon 4-11) in childhood acute lymphoblastic leukemia (B and T-ALL) patients (n = 94) including diagnostic-relapse pairs (n = 15) by amplicon sequencing and evaluate the clinical impact of these variants. In total, nine different (E298*, R283C, R273H, L252F, C229F, I195T, E286G, c.955_956insC, and c.920-1G > C) variants were identified in 17 (18%) childhood ALL patients. c.(920-1G> C) splice site variant and c.(955_956insC) insertion were reported for the first time. In diagnose-relapse pair samples, we identified acquired and/or loss of TP53 variants in the samples at the time of relapse. TP53 variants were found to be more common in T-ALL (37%) than in B-ALL patients (9%). Pathogenic TP53 variants were associated with a shorter overall survival time (p = 0.001).TP53 variants were found to be associated with inferior outcomes in our cohort and can be an independent risk factor for poor prognosis in childhood acute leukemia patients. Identification of low-frequent variants with next-generation sequencing approaches enables better knowledge of the clonal dynamics of ALL.

Modeling Blast Crisis Using Mutagenized Chronic Myeloid Leukemia-Derived Induced Pluripotent Stem Cells (iPSCs).

PURPOSE: To model CML progression in vitro and generate a blast crisis (BC-CML) model in vitro in order to identify new targets. METHODS: Three different CML-derived iPSC lines were mutagenized with the alkylating agent ENU on a daily basis for 60 days. Cells were analyzed at D12 of hematopoietic differentiation for their phenotype, clonogenicity, and transcriptomic profile. Single-cell RNA-Seq analysis has been performed at three different time points during hematopoietic differentiation in ENU-treated and untreated cells. RESULTS: One of the CML-iPSCs, compared to its non-mutagenized counterpart, generated myeloid blasts after hematopoietic differentiation, exhibiting monoblastic patterns and expression of cMPO, CD45, CD34, CD33, and CD13. Single-cell transcriptomics revealed a delay of differentiation in the mutated condition as compared to the control with increased levels of MSX1 (mesodermal marker) and a decrease in CD45 and CD41. Bulk transcriptomics analyzed along with the GSE4170 GEO dataset reveal a significant overlap between ENU-treated cells and primary BC cells. Among overexpressed genes, CD25 was identified, and its relevance was confirmed in a cohort of CML patients. CONCLUSIONS: iPSCs are a valuable tool to model CML progression and to identify new targets. Here, we show the relevance of CD25 identified in the iPSC model as a marker of CML progression.

Zinc finger protein 384 (ZNF384) impact on childhood mixed phenotype acute leukemia and B-cell precursor acute lymphoblastic leukemia.

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is a heterogeneous malignancy and consists of several genetic abnormalities. Some of these abnormalities are used in clinics for risk calculation and treatment decisions. Patients with ZNF384 rearrangements had a distinct expression profile regardless of their diagnosis, BCP-ALL or mixed phenotype acute leukemia (MPAL) and defined as a new subtype of ALL. In this study, we screened 42 MPAL and 91 BCP-ALL patients for the most common ZNF384 fusions; ZNF384::TCF3, ZNF384::EP300 and ZNF384::TAF15 by using PCR. We identified ZNF384 fusions in 9.5% of MPAL and 7.6% of BCP-ALL. A novel breakpoint was identified in ZNF384::TCF3 fusion in one BCP-ALL patient. T-myeloid MPAL patients showed significantly lower ZNF384 expression compared to lymphoid groups. Patients with ZNF384r had intermediate survival rates based on other subtypes. Prognostic and patient-specific treatment evaluation of ZNF384 fusions in both ALL and MPAL might help to improve risk characterization of patients.

Obstacles and expectations of rare disease patients and their families in Türkiye: ISTisNA project survey results.

Rare disease patients constitute a significant part of the healthcare system of all countries. However, the information on the experiences during disease processes and daily life of rare disease patients is still limited. So far, there is a small number of studies conducted in Türkiye, and they mainly cover specific issues like education or anxiety. Here we present a comprehensive survey analysis conducted among the patients and their families within the scope of the Istanbul Solution Platform for Undiagnosed and Rare Diseases-ISTisNA project. A total of 498 individuals responded to the survey, and 58% of the participants answered all questions. The majority of the patients were in the age range of 1-10 years (44.7%), and 91% of all the patients had a precise diagnosis. The diagnosis rate in the first 6 months was 69%, and almost 10% of the patients remained undiagnosed. The mothers were the primary caregivers (72%). Nearly 30% of the caregivers had to quit their jobs and 25% of the patients (0-18 years) had to leave school. Accessing physicians with relevant specialization and reaching treatments/medications/supplements were the two main obstacles the participants mentioned, with a frequency of 81% and 73%, respectively. Around 50% of participants noted that they commonly faced difficulties at work/school and in their social lives. The highest expectation or priority was the establishment of rare disease-specific diagnosis and treatment centers, accurate and detailed information on diseases in the Turkish language, and easy access to physicians, treatments, and supportive therapies. To the best of our knowledge, this is the most comprehensive survey conducted on the rare disease community in Türkiye. These results show that regardless of the country, the individuals affected by rare diseases and their families have similar problems and expectations. On the other hand, regional and country-specific issues are still in the line to be solved. These studies can provide a deeper insight into rare diseases and guide the activities of Türkiye's national rare disease action plan.

Prognostic evidence of LEF1 isoforms in childhood acute lymphoblastic leukemia.

INTRODUCTION: The lymphoid enhancer factor 1 (LEF1) is a DNA-binding transcription factor that functions in the Wnt signaling pathway. Increased LEF1 activity is associated with progression of several types of cancer including leukemia. Here, we investigated LEF1 isoform expression and genomic variations in acute lymphoblastic leukemia (ALL). METHODS: LEF1 isoform expression was evaluated by quantitative real-time PCR in 87 newly diagnosed childhood ALL patients and controls. Moreover, Western blot analysis was performed for detection of LEF1 expression and the hotspot region of LEF1 was screened by deep sequencing. RESULTS: The LEF1 mRNA expression of B cell ALL patients was higher than the controls (LEF1-total P = .011, LEF1-long P = .026). Moreover, B-ALL samples showing higher total LEF1 expression had significantly shorter relapse-free survival (P = .008) and overall survival (P = .011). Although full-length LEF1 expression was similar to the controls in T-ALL, 50% (n = 15) of the ALL patients had increased full-length LEF1 protein expression. Imbalance between short- and full-length LEF1 isoforms may lead to cell survival in ALL. Beside the LEF1 activation, LEF1 gene variations were rarely observed in our cohort. CONCLUSION: The results indicate that the Wnt pathway may have a pathogenic function in a group of ALL patients and high LEF1-total expression might be a marker for shorter relapse-free survival time in B cell ALL.

Lymphoma Predisposing Gene in an Extended Family: CD70 Signaling Defect.

Genome-wide sequencing studies in pediatric cancer cohorts indicate that about 10% of patients have germline mutations within cancer predisposition genes. Within this group, primary immune deficiencies take the priority regarding the vulnerability of the patients to infectious agents and the difficulties of cancer management. On the other hand, early recognition of these diseases may offer specific targeted therapies and hematopoietic stem cell transplantation as an option. Besides therapeutic benefits, early diagnosis will provide genetic counseling for the family members. Within this context, an extended family with multiple consanguineous marriages and affected individuals, who presented with combined immune deficiency (CID) and/or Hodgkin lymphoma phenotype, were examined by exome sequencing. A pathogenic homozygous missense CD70 variation was detected (NM_001252.5:c332C>T) in concordance with CD70 phenotype and familial segregation was confirmed. CD70 variations in patients with CID and malignancy have very rarely been reported. This paper reports extended family with multiple affected members with CID and malignancy carrying a missense CD70 variation, and reviews the rare cases reported in the literature. Primary immune deficiencies appear to be a potential cause for pediatric cancers. Better focusing on these inborn disorders to prevent or make an early diagnosis of malignant transformation and reduce mortalities is important.

PTEN and AKT1 Variations in Childhood T-Cell Acute Lymphoblastic Leukemia

Objective: PTEN/AKT pathway deregulations have been reported to be associated with treatment response in acute leukemia. This study examined pediatric T-cell acute lymphoblastic leukemia (T-ALL) samples for PTEN and AKT1 gene variations and evaluated the clinical findings. Materials and Methods: Fifty diagnostic bone marrow samples of childhood T-ALL cases were investigated for the hotspot regions of the PTEN and AKT1 genes by targeted next-generation sequencing. Results: A total of five PTEN variations were found in three of the 50 T-ALL cases (6%). Three of the PTEN variations were first reported in this study. Furthermore, one patient clearly had two different mutant clones for PTEN. Two intronic single-nucleotide variations were found in AKT1 and none of the patients carried pathogenic AKT1 variations. Conclusion: Targeted deep sequencing allowed us to detect both low-level variations and clonal diversity. Low-level PTEN/AKT1 variation frequency makes it harder to investigate the clinical associations of the variants. On the other hand, characterization of the PTEN/AKT signaling members is important for improving case-specific therapeutic strategies.

Prognostic gene alterations and clonal changes in childhood B-ALL.

Genomic profiles of leukemia patients lead to characterization of variations that provide the molecular classification of risk groups, prediction of clinical outcome and therapeutic decisions. In this study, we examined the diagnostic (n = 77) and relapsed (n = 31) pediatric B-cell acute lymphoblastic leukemia (B-ALL) samples for the most common leukemia-associated gene variations CRLF2, JAK2, PAX5 and IL7R using deep sequencing and copy number alterations (CNAs) (CDKN2A/2B, PAX5, RB1, BTG1, ETV6, CSF2RA, IL3RA and CRLF2) by multiplex ligation proximity assay (MLPA), and evaluated for the clonal changes through relapse. Single nucleotide variations SNVs were detected in 19% of diagnostic 15.3% of relapse samples. The CNAs were detected in 55% of diagnosed patients; most common affected genes were CDKN2A/2B, PAX5, and CRLF2. Relapse samples did not accumulate a greater number of CNAs or SNVs than the cohort of diagnostic samples, but the clonal dynamics showed the accumulation/disappearance of specific gene variations explained the course of relapse. The CDKN2A/2B were most frequently altered in relapse samples and 32% of relapse samples carried at least one CNA. Moreover, CDKN2A/2B alterations and/or JAK2 variations were associated with decreased relapse-free survival. On the other hand, CRLF2 copy number alterations predicted a better survival rate in B-ALL. These findings contribute to the knowledge of CDKN2A/2B and CRLF2 alterations and their prognostic value in B-ALL. The integration of genomic data in clinical practice will enable better stratification of ALL patients and allow deeper understanding of the nature of relapse.

Deep sequencing of BCR-ABL1 kinase domain mutations in chronic myeloid leukemia patients with resistance to tyrosine kinase inhibitors.

Tyrosine kinase inhibitor (TKI) therapy is the current treatment of choice for patients with chronic phase chronic myeloid leukemia (CML) leading to rapid and durable hematological as well as molecular responses. However, emergence of resistance to TKIs has been the major obstacle to treatment success on long term. In this regard kinase domain mutations are the most common mechanism of therapy failure. In this study, we analyzed peripheral blood samples from 17 CML patients who had developed resistance to various TKIs by using next-generation sequencing parallel to Sanger sequencing. BCR-ABL1 kinase domain mutations have been found in 59% of the cohort. Our results demonstrate that next-generation sequencing results in a higher mutational detection rate than reported with conventional sequencing methodology. Furthermore, it showed the clonal diversity more accurately.

Third-line treatment with second-generation tyrosine kinase inhibitors (dasatinib or nilotinib) in patients with chronic myeloid leukemia after two prior TKIs: real-life data on a single center experience along with the review of the literature.

OBJECTIVES: Newer tyrosine kinase inhibitors (TKIs) (bosutinib, ponatinib) and allogeneic hematopoietic stem cell transplantation (allo-HSCT) can be utilized as a salvage therapy in patients with chronic myeloid leukemia (CML) who failed two lines (imatinib → nilotinib or imatinib → dasatinib) of TKI therapy. However, these TKIs are not available in many countries and not all patients can undergo allo-HSCT. METHODS: In this study, CML patients who received dasatinib or nilotinib as a third-line treatment were retrospectively evaluated. RESULTS: Out of 209 patients, third-line dasatinib/nilotinib was administered in 21. During the follow-up, 16 out of 21 patients gained and/or maintained an optimal response, and 4 patients died due to progression. Seventeen patients were alive at the time of the analysis, of which 13 were still on TKI, whereas 4 patients quit treatment. DISCUSSION: In patients failing two lines of TKI, dasatinib or nilotinib can be beneficial and safely administered as a third-line treatment especially in nations with restricted resources.

Dysregulation of the DKK1 gene in pediatric B-cell acute lymphoblastic leukemia.

BACKGROUND/AIM: The canonical Wingless-type (WNT) pathway is involved in normal hematopoietic cell development and deregulated WNT signaling is implicated in the development of hematological malignancies. Dickkopf 1 (DKK1) acts as a modulator of the ß-catenin regulated canonical pathway. Activation of DKK1 leads to apoptosis and growth suppression, whereas silencing by promoter hypermethylation results in abnormal WNT activation. The secreted inhibitor Dickkopf can antagonize WNT signaling by competitively binding to low density lipoprotein receptors (LRPs) 5 and 6. MATERIALS AND METHODS: We studied DKK1 gene promoter methylation and investigated DKK1, ß-catenin, LRP5, and LRP6 mRNA levels in B-cell acute lymphoblastic leukemia (B-ALL) patients (n = 90). Methylation-specific PCR and bisulfite sequencing were used for methylation profiling and quantitative real-time PCR was used for mRNA detection. RESULTS: The DKK1 gene was examined for its promoter methylation and only 33% of patients were found methylated. On the other hand, B-ALL cases showed high expression of DKK1 (P = 0.01), LRP5 (P = 0.04), and LRP6 (P = 0.02) compared to normal bone marrow cells. CONCLUSION: DKK1 methylation exists in some of cases but is not sufficient for WNT pathway activation alone in pediatric B-ALL.

Local Renin-Angiotensin system in normal hematopoietic and multiple myeloma-related progenitor cells.

OBJECTIVE: The prominent functions of the local renin-angiotensin system (RAS) in primitive hematopoiesis further support the hypothesis that local autocrine bone marrow RAS could also be active in neoplastic hematopoiesis. The aim of this study is to examine critical RAS elements in normal CD34+ hematopoietic stem cells and multiple myeloma (MM)-related progenitor cells. MATERIALS AND METHODS: The study group comprised the total bone marrow cells (CBM) of 10 hematologically normal people, the CD34+ stem cell samples (CD34+CBM) of 9 healthy donors for allogeneic peripheral stem cell transplantation, and the CD34+ stem cell samples (CD34+MM) of 9 MM patients undergoing autologous peripheral stem cell transplantation. We searched for the gene expression of the major RAS components in healthy hematopoietic cells and myeloma cells by quantitative real-time polymerase chain reaction analysis. RESULTS: RENIN, angiotensinogen (ANGTS), and angiotensin converting enzyme-I (ACE I) mRNA expression levels of CBM were significantly higher than those in myeloma patients (p=0.03, p=0.002, and p=0.0008, respectively). Moreover, RENIN and ANGTS mRNA expression levels were significantly higher in CD34+ stem cell samples of healthy allogeneic donors compared to those in myeloma patients (p=0.001 and p=0.01). However, ACE I expression levels were similar in CD34+CBM and CD34+MM hematopoietic cells (p=0.89). CONCLUSION: Although found to be lower than in the CBM and CD34+CBM hematopoietic cells, the local RAS components were also expressed in CD34+MM hematopoietic cells. This point should be kept in mind while focusing on the immunobiology of MM and the processing of autologous cells during the formation of transplantation treatment protocols.

Parallel visualization of multiple protein complexes in individual cells in tumor tissue.

Cellular functions are regulated and executed by complex protein interaction networks. Accordingly, it is essential to understand the interplay between proteins in determining the activity status of signaling cascades. New methods are therefore required to provide information on different protein interaction events at the single cell level in heterogeneous cell populations such as in tissue sections. Here, we describe a multiplex proximity ligation assay for simultaneous visualization of multiple protein complexes in situ. The assay is an enhancement of the original proximity ligation assay, and it is based on using proximity probes labeled with unique tag sequences that can be used to read out which probes, from a pool of probes, have bound a certain protein complex. Using this approach, it is possible to gain information on the constituents of different protein complexes, the subcellular location of the complexes, and how the balance between different complex constituents can change between normal and malignant cells, for example. As a proof of concept, we used the assay to simultaneously visualize multiple protein complexes involving EGFR, HER2, and HER3 homo- and heterodimers on a single-cell level in breast cancer tissue sections. The ability to study several protein complex formations concurrently at single cell resolution could be of great potential for a systems understanding, paving the way for improved disease diagnostics and possibilities for drug development.

Local hematopoietic renin-angiotensin system in myeloid versus lymphoid hematological neoplastic disorders.

There is preliminary evidence that the local renin-angiotensin system (RAS) could affect neoplastic hematopoiesis. The aim of this study is to search messenger RNA (mRNA) expressions of the essential RAS elements in myeloid and lymphoid hematological neoplastic disorders. Forty-six patients with newly diagnosed myeloid (AML, biphenotypic leukemia, CML) or lymphoid (CLL, NHL, B-ALL, T-ALL) hematological disorders were included in the study. In the lymphoid group, the median expression values of RENIN, ACE1, ACE2 and ANGIOTENSINOGEN (ANGTS) mRNAs were 1.96%, 0.42%, 0.00% and 0.00%, respectively; in the myeloid group, 0.73%, 1.55%, 0.04% and 0.006%, respectively. In the lymphoid group, RENIN levels were significantly higher (p = 0.001), whereas ACE1 and ACE2 levels were significantly higher in the myeloid group (p values were 0.013 and 0.010, respectively). ANGTS levels were similar in both groups. In patients with non-ALL lymphoid malignancies, RENIN expressions were significantly higher when compared to ALL patients (p = 0.004). All patients with active disease had significantly higher RENIN mRNA expression levels than patients without active disease (2.03% vs 0.30%) (p = 0.034). The result of our present study indicates that the activities of local RAS may differ in distinct disease states such as leukemia and lymphomas.

Elevated TRIB2 with NOTCH1 activation in paediatric/adult T-ALL.

TRIB2 is a potent oncogene, elevated in a subset of human acute myeloid leukaemias (AML) with a mixed myeloid/lymphoid phenotype and NOTCH1 mutations. Although rare in AML, activating NOTCH1 mutations occur in 50% of all T cell acute lymphoblastic leukaemias (T-ALL). TRIB2 is a NOTCH1 target gene that functions in the degradation of key proteins and modulation of MAPK signalling pathways, implicated in haematopoietic cell survival and proliferation. This study showed that TRIB2 expression level is highest in the lymphoid compartment of normal haematopoietic cells, specifically in T cells. Analysis of TRIB2 expression across 16 different subtypes of human leukaemia demonstrated that TRIB2 expression was higher in ALL phenotypes versus all other phenotypes including AML, chronic lymphocytic leukaemia (CLL), myelodysplastic syndrome (MDS) and chronic myeloid leukaemia (CML). A T cell profile was distinguished by high TRIB2 expression in normal and malignant haematopoiesis. High TRIB2 expression was seen in T-ALL with normal karyotype and correlated with NOTCH signalling pathways. High TRIB2 expression correlated with NOTCH1/FBXW7 mutations in a paediatric T-ALL cohort, strongly linking NOTCH1 activation and high TRIB2 expression in paediatric T-ALL. The relationship between TRIB2 and T cell signalling pathways uniquely identifies leukaemia subtypes and will be useful in the advancement of our understanding of T cell and ALL biology.

Evaluation of PAX5 gene in the early stages of leukemic B cells in the childhood B cell acute lymphoblastic leukemia.

B-lineage acute lymphoblastic leukemia (B-ALL) is a common subtype of acute leukemia in children. PAX5 plays a central role in B-cell development and differentiation. In this study, we analyzed PAX5 expression levels, transactivation domain mutations/deletions in B-ALL patients (n=115) and healthy controls (n=10). Relative PAX5 mRNA levels were significantly increased in B-ALL patients (p<0.0001). PAX5 expression was also evaluated in three different B-ALL subgroups (pro B, Common B and Pre B ALL) and showed stage specific expression levels. Pro B (p=0.04) and pre B (p=0.04) patients showed significantly high PAX5 mRNA levels compared to stage specific controls. At least one deletion of exons 7-8 or 9 has been identified in the 41% of the patients. CD34 positivity in patients and presence of large deletions (Δ7/8/9) showed a significant correlation (p=0.05). None of our patients showed PAX5 point mutations, but two previously identified SNPs (rs3780135 and rs35469494) were detected. Our results support that PAX5 is a critical factor in B-ALL development and aberrant PAX5 expression especially at early stages may leads to leukemic transformation.

Upregulation of T-Cell-Specific Transcription Factor Expression in Pediatric T-Cell Acute Lymphoblastic Leukemia (T-ALL).

OBJECTIVE: T-cell acute lymphoblastic leukemia (T-ALL) is associated with recurrent chromosomal aberrations andabnormal ectopic gene expression during T-cell development. In order to gain insight into the pathogenesis of T-ALLthis study aimed to measure the level of expression of 7 T-cell oncogenes (LMO2, LYL1, TAL1, TLX1, TLX3, BMI1, andCALM-AF10) in pediatric T-ALL patients Material and Methods: LMO2, LYL1, TLX1, TLX3, BMI1, TAL1, and CALM-AF10 expression was measured usingquantitative real-time PCR in 43 pediatric T-ALL patients. RESULTS: A high level of expression of LMO2, LYL1, TAL1, and BMI1 genes was observed in a large group of T-ALL.Several gene expression signatures indicative of leukemic arrest at specific stages of normal thymocyte development(LYL1 and LMO2) were highly expressed during the cortical and mature stages of T-cell development. Furthermore,upregulated TAL1 and BMI1 expression was observed in all phenotypic subgroups. In all, 6 of the patients had TLX1and TLX3 proto-oncogene expression, which does not occur in normal cells, and none of the patients had CALM-AF10fusion gene transcription. Expression of LYL1 alone and LMO2-LYL1 co-expression were associated with mediastinalinvolvement; however, high-level oncogene expression was not predictive of outcome in the present pediatric T-ALLpatient group, but there was a trend towards a poor prognostic impact of TAL1 and/or LMO2 and/or LYL1 protooncogeneexpression. CONCLUSION: Poor prognostic impact of TAL1 and/or LMO2 and/or LYL1 proto-oncogene expression indicate the needfor extensive study on oncogenic rearrangement and immunophenotypic markers in T-ALL, and their relationship totreatment outcome. CONFLICT OF INTEREST: None declared.