Genetic hallmarks and clinical implications of chromothripsis in childhood T-cell acute lymphoblastic leukemia.

Chromothripsis (cth) is a form of genomic instability leading to massive de novo structural chromosome rearrangements in a one-time catastrophic event. It can cause cancer-promoting alterations, such as loss of sequences for tumor-suppressor genes, formation of oncogenic fusions, and oncogene amplifications. We investigated the genetic background and clinical significance of cth in childhood T-cell acute lymphoblastic leukemia (T-ALL) patients. For this purpose, whole-genome copy number alterations were analyzed in 173 children with newly diagnosed T-ALL using high-density microarrays. Cth was identified in 10 T-ALL samples (5.78%). In six of them, cth occurred in a constitutional background of Nijmegen breakage syndrome (n = 5) or Li-Fraumeni syndrome (n = 1). Cth generated alterations, including deletions of CDKN2A/B (n = 4) and EZH2 (n = 4), amplifications of CDK6 (n = 2), and NUP214::ABL1 and TFG::GPR128 fusions. Cth-positive leukemias exhibited deletions involving the tumor-suppressor genes RB1 (n = 3), TP53 (n = 1) and MED12 (n = 2). Cth-positive T-ALL patients had a lower probability of 5-year overall survival (OS) [0.56 vs. 0.81; hazard ratio (HR) = 4.14 (1.42-12.02) p = 0.017] as did 5-year event-free survival [0.45 vs. 0.74; HR = 3.91 (1.52-10.08); p = 0.012]. Chromothripsis is an infrequent genomic phenomenon in pediatric T-ALL but is significantly associated with cancer-predisposing syndromes and may associate with inferior prognosis.

Asciminib stands out as the superior tyrosine kinase inhibitor to combine with anti-CD20 monoclonal antibodies for the treatment of CD20+ Philadelphia-positive B-cell precursor acute lymphoblastic leukemia in preclinical models.

Philadelphia chromosome-positive B-cell precursor acute lymphoblastic leukemia (Ph+ BCPALL) is a high-risk acute lymphoblastic leukemia subtype characterized by the presence of BCR::ABL1 fusion gene. Tyrosine kinase inhibitors (TKIs) combined with chemotherapy are established as the first-line treatment. Additionally, rituximab (RTX), an anti-CD20 monoclonal antibody (mAb) is administered in adult BCP-ALL patients with ≥20% of CD20+ blasts. In this study, we observed a marked prevalence of CD20 expression in patients diagnosed with Ph+ BCP-ALL, indicating a potential widespread clinical application of RTX in combination with TKIs. Consequently, we examined the influence of TKIs on the antitumor effectiveness of anti-CD20 mAbs by evaluating CD20 surface levels and conducting in vitro functional assays. All tested TKIs were found to uniformly downregulate CD20 on leukemic cells, diminishing the efficacy of RTX-mediated complement-dependent cytotoxicity. Interestingly, these TKIs displayed varied effects on NK cell-mediated antibody-dependent cytotoxicity and macrophage phagocytic function. While asciminib demonstrated no inhibition of effector cell functions, dasatinib notably suppressed the anti-CD20-mAb-mediated NK cell cytotoxicity and macrophage phagocytosis of BCP-ALL cells. Dasatinib and ponatinib also decreased NK cell degranulation in vitro. Importantly, oral administration of dasatinib, but not asciminib, compromised NK cell activity within patients' blood, determined by ex vivo degranulation assay. Our results indicate that asciminib might be preferred over other TKIs for combination therapy with anti-CD20 mAbs.

ATM germ line pathogenic variants affect outcomes in children with ataxia-telangiectasia and hematological malignancies.

ABSTRACT: Ataxia-telangiectasia (A-T) is an autosomal-recessive disorder caused by pathogenic variants (PVs) of the ATM gene, predisposing children to hematological malignancies. We investigated their characteristics and outcomes to generate data-based treatment recommendations. In this multinational, observational study we report 202 patients aged ≤25 years with A-T and hematological malignancies from 25 countries. Ninety-one patients (45%) presented with mature B-cell lymphomas, 82 (41%) with acute lymphoblastic leukemia/lymphoma, 21 (10%) with Hodgkin lymphoma and 8 (4%) with other hematological malignancies. Four-year overall survival and event-free survival (EFS) were 50.8% (95% confidence interval [CI], 43.6-59.1) and 47.9% (95% CI 40.8-56.2), respectively. Cure rates have not significantly improved over the last four decades (P = .76). The major cause of treatment failure was treatment-related mortality (TRM) with a four-year cumulative incidence of 25.9% (95% CI, 19.5-32.4). Germ line ATM PVs were categorized as null or hypomorphic and patients with available genetic data (n = 110) were classified as having absent (n = 81) or residual (n = 29) ATM kinase activity. Four-year EFS was 39.4% (95% CI, 29-53.3) vs 78.7% (95% CI, 63.7-97.2), (P < .001), and TRM rates were 37.6% (95% CI, 26.4-48.7) vs 4.0% (95% CI, 0-11.8), (P = .017), for those with absent and residual ATM kinase activity, respectively. Absence of ATM kinase activity was independently associated with decreased EFS (HR = 0.362, 95% CI, 0.16-0.82; P = .009) and increased TRM (hazard ratio [HR] = 14.11, 95% CI, 1.36-146.31; P = .029). Patients with A-T and leukemia/lymphoma may benefit from deescalated therapy for patients with absent ATM kinase activity and near-standard therapy regimens for those with residual kinase activity.

An artificial intelligence-assisted clinical framework to facilitate diagnostics and translational discovery in hematologic neoplasia.

BACKGROUND: The increasing volume and intricacy of sequencing data, along with other clinical and diagnostic data, like drug responses and measurable residual disease, creates challenges for efficient clinical comprehension and interpretation. Using paediatric B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) as a use case, we present an artificial intelligence (AI)-assisted clinical framework clinALL that integrates genomic and clinical data into a user-friendly interface to support routine diagnostics and reveal translational insights for hematologic neoplasia. METHODS: We performed targeted RNA sequencing in 1365 cases with haematological neoplasms, primarily paediatric B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) from the AIEOP-BFM ALL study. We carried out fluorescence in situ hybridization (FISH), karyotyping and arrayCGH as part of the routine diagnostics. The analysis results of these assays as well as additional clinical information were integrated into an interactive web interface using Bokeh, where the main graph is based on Uniform Manifold Approximation and Projection (UMAP) analysis of the gene expression data. At the backend of the clinALL, we built both shallow machine learning models and a deep neural network using Scikit-learn and PyTorch respectively. FINDINGS: By applying clinALL, 78% of undetermined patients under the current diagnostic protocol were stratified, and ambiguous cases were investigated. Translational insights were discovered, including IKZF1plus status dependent subpopulations of BCR::ABL1 positive patients, and a subpopulation within ETV6::RUNX1 positive patients that has a high relapse frequency. Our best machine learning models, LDA and PASNET-like neural network models, achieve F1 scores above 97% in predicting patients' subgroups. INTERPRETATION: An AI-assisted clinical framework that integrates both genomic and clinical data can take full advantage of the available data, improve point-of-care decision-making and reveal clinically relevant insights promptly. Such a lightweight and easily transferable framework works for both whole transcriptome data as well as the cost-effective targeted RNA-seq, enabling efficient and equitable delivery of personalized medicine in small clinics in developing countries. FUNDING: German Ministry of Education and Research (BMBF), German Research Foundation (DFG) and Foundation for Polish Science.

Concomitant inhibition of the thioredoxin system and nonhomologous DNA repair potently sensitizes Philadelphia-positive lymphoid leukemia to tyrosine kinase inhibitors.

Breakpoint cluster region-Abelson (BCR::ABL1) gene fusion is an essential oncogene in both chronic myeloid leukemia (CML) and Philadelphia-positive (Ph+) B-cell acute lymphoblastic leukemia (B-ALL). While tyrosine kinase inhibitors (TKIs) are effective in up to 95% of CML patients, 50% of Ph+ B-ALL cases do not respond to treatment or relapse. This calls for new therapeutic approaches for Ph+ B-ALL. Previous studies have shown that inhibitors of the thioredoxin (TXN) system exert antileukemic activity against B-ALL cells, particularly in combination with other drugs. Here, we present that peroxiredoxin-1 (PRDX1), one of the enzymes of the TXN system, is upregulated in Ph+ lymphoid as compared to Ph+ myeloid cells. PRDX1 knockout negatively affects the viability of Ph+ B-ALL cells and sensitizes them to TKIs. Analysis of global gene expression changes in imatinib-treated, PRDX1-deficient cells revealed that the nonhomologous end-joining (NHEJ) DNA repair is a novel vulnerability of Ph+ B-ALL cells. Accordingly, PRDX1-deficient Ph+ B-ALL cells were susceptible to NHEJ inhibitors. Finally, we demonstrated the potent efficacy of a novel combination of TKIs, TXN inhibitors, and NHEJ inhibitors against Ph+ B-ALL cell lines and primary cells, which can be further investigated as a potential therapeutic approach for the treatment of Ph+ B-ALL.

Raman spectroscopy can recognize the KMT2A rearrangement as a distinct subtype of leukemia.

Acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) are the two most common hematologic malignancies, challenging to treat and associated with high recurrence and mortality rates. This work aims to identify specific Raman biomarkers of ALL cells with the KMT2A gene rearrangement (KMT2A-r), representing a highly aggressive subtype of childhood leukemia with a poor prognosis. The proposed approach combines the sensitivity and specificity of Raman spectroscopy with machine learning and allows us to distinguish not only myelo- and lymphoblasts but also discriminate B-cell precursor (BCP) ALL with KMT2A-r from other blasts of BCP-ALL. We have found that KMT2A-r ALL cells fixed with 0.5% glutaraldehyde exhibit a unique spectroscopic profile that enables us to identify this subtype from other leukemias and normal cells. Therefore, a rapid and label-free method was developed to identify ALL blasts with KMT2A-r based on the ratio of the two Raman bands assigned to phenylalanine - 1040 and 1008 cm-1. This is the first time that a particular group of leukemic cells has been identified in a label-free way. The identified biomarker can be used as a screening method in diagnostic laboratories or non-reference medical centers.

Raman classification of selected subtypes of acute lymphoblastic leukemia (ALL).

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) with chromosome translocations like KMT2A gene rearrangement (KMT2A-r) and BCR-ABL1 fusion gene have been recognized as crucial drivers in both BCP-ALL leukemogenesis and treatment management. Standard diagnostic protocols for proliferative diseases of the hematopoietic system, like KMT2A-r-ALL, are genetically based and strongly molecularly oriented. Therefore, an efficient diagnostic procedure requires not only experienced and multidisciplinary laboratory staff but also considerable instrumentation and material costs. In recent years, a Raman spectroscopy method has been increasingly used to detect subtle chemical changes in individual cells resulting from stress or disease. Therefore, the objective of this study was to identify Raman signatures for the molecular subtypes and to develop a classification method based on the unique spectroscopic profile of in vitro models that represent specific aberrations aimed at KMT2A-r (RS4;11, and SEM) and the BCR-ABL1 fusion gene (SUP-B15, BV-173, and SD-1). Data analysis was based on chemometric methods, i.e. principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and support vector machine (SVM). The PCA-based multivariate model was used for pattern recognition of each investigated group of cells while PLS-DA and SVM were used to build models for the discrimination of spectra from the studied BCP-ALL molecular subtypes. The results showed that the studied molecular subtypes of ALL have characteristic spectroscopic profiles reflecting their peculiar biochemical state. The content of lipids (1600 cm-1), nucleic acids (789 cm-1), and haemoproteins (754, 1130, and 1315 cm-1), which are crucial in cell metabolism, was indicated as the main source of differentiation between subtypes. Identification of spectroscopic markers of cells with BCR-ABL1 or KMT2A-r may be useful in pharmacological studies to monitor the effectiveness of chemotherapy and further to understand differences in molecular responses between leukemia primary cells and cell lines.

An Asymptomatic, Ectopic Mass as a Presentation of Adrenocortical Carcinoma Due to a Novel Germline TP53 p.Phe338Leu Tetramerisation Domain Variant.

Adrenocortical carcinoma (ACC) is a rare cancer in childhood. ACC is frequently associated with germline TP53 variants, with founder effects especially due to the p.Arg337His mutation. ACC leads to the secretion of adrenocortical hormones, resulting in endocrine syndromes, which is the usual trigger for establishing the diagnosis. We present a surprising ACC pathology in a non-secreting, ectopic retroperitoneal tumour in a 4-year-old boy, successfully controlled with chemotherapy and mitotane after microscopically incomplete tumour resection with spillage. Genomic analysis (gene panel sequencing and copy-number microarray) demonstrated a novel p.Phe338Leu tetramerisation domain (TD) TP53 variant in the proband and his cancer-free mother and a monoallelic deletion encompassing the TP53 locus in cancer tissue, consistent with cancer-predisposition syndrome. While the recurrent p.Arg337His variant translates into high ACC risk, residue 338 and, in general, TD domain variants drive heterogeneous clinical scenarios, despite generally being considered less disruptive than TP53 DNA-binding domain mutations.

A significant proportion of classic Hodgkin lymphoma recurrences represents clonally unrelated second primary lymphoma.

Despite high cure rates in classic Hodgkin lymphoma (cHL), relapses are observed. Whether relapsed cHL represents second primary lymphoma or an underlying T-cell lymphoma (TCL) mimicking cHL is underinvestigated. To analyze the nature of cHL recurrences, in-depth clonality testing of immunoglobulin (Ig) and T-cell receptor (TCR) rearrangements was performed in paired cHL diagnoses and recurrences among 60 patients, supported by targeted mutation analysis of lymphoma-associated genes. Clonal Ig rearrangements were detected by next-generation sequencing (NGS) in 69 of 120 (58%) diagnoses and recurrence samples. The clonal relationship could be established in 34 cases, identifying clonally related relapsed cHL in 24 of 34 patients (71%). Clonally unrelated cHL was observed in 10 of 34 patients (29%) as determined by IG-NGS clonality assessment and confirmed by the identification of predominantly mutually exclusive gene mutations in the paired cHL samples. In recurrences of >2 years, ∼60% of patients with cHL for whom the clonal relationship could be established showed a second primary cHL. Clonal TCR gene rearrangements were identified in 14 of 125 samples (11%), and TCL-associated gene mutations were detected in 7 of 14 samples. Retrospective pathology review with integration of the molecular findings were consistent with an underlying TCL in 5 patients aged >50 years. This study shows that cHL recurrences, especially after 2 years, sometimes represent a new primary cHL or TCL mimicking cHL, as uncovered by NGS-based Ig/TCR clonality testing and gene mutation analysis. Given the significant therapeutic consequences, molecular testing of a presumed relapse in cHL is crucial for subsequent appropriate treatment strategies adapted to the specific lymphoma presentation.

Venetoclax Use in Paediatric Haemato-Oncology Centres in Poland: A 2022 Survey.

Venetoclax, the best established BH3-mimetic, is a practice-changing proapoptotic drug in blood cancers in adults. In paediatrics the data are fewer but exciting results were recently presented in relapsed or refractory leukaemias demonstrating significant clinical activity. Importantly, the in-terventions could be potentially molecularly guided as vulnerabilities to BH3-mimetics were re-ported. Currently venetoclax is not incorporated into paediatric treatment schedules in Poland but it has been already used in patients that failed conventional therapy in Polish paediatric haemato-oncology departments. The aim of the study was to gather clinical data and correlates of all paediatric patients treated so far with venetoclax in Poland. We set out to gather this experience to help choose the right clinical context for the drug and stimulate further research. The questionnaire regarding the use of venetoclax was sent to all 18 Polish paediatric haemato-oncology centres. The data as available in November 2022 were gathered and analysed for the diagnoses, triggers for the intervention, treatment schedules, outcomes and molecular associations. We received response from 11 centres, 5 of which administered venetoclax to their patients. Clinical benefit, in most cases consistent with hematologic complete remission (CR), was reported in 5 patients out of ten, whereas 5 patient did not show clinical benefit from the intervention. Importantly, patients with CR included subtypes expected to show venetoclax vulnerability, such as poor-prognosis ALL with TCF::HLF fusion. We believe BH3-mimetics have clinical activity in children and should be available to pae-diatric haemato-oncology practitioners in well-selected applications.

Reliable cell preparation protocol for Raman imaging to effectively differentiate normal leukocytes and leukemic blasts.

Leukemias are a remarkably diverse group of malignancies originating from abnormal progenitor cells in the bone marrow. Leukemia subtypes are classified according to the cell type that has undergone neoplastic transformation using demanding and time-consuming methods. Alternative is Raman imaging that can be used both for living and fixed cells. However, considering the diversity of leukemic cell types and normal leukocytes, and the availability of different sample preparation protocols, the main objective of this work was to verify them for leukemia and normal blood cell samples for Raman imaging. The effect of glutaraldehyde (GA) fixation in a concentration gradient (0.1 %, 0.5 %, and 2.5 % GA) on the molecular structure of T-cell acute lymphoblastic leukemia (T-ALL) and peripheral blood mononuclear cells (PBMCs) was verified. Changes in the secondary structure of proteins within cells were indicated as the main effect of fixation, as shown by an increase in band intensity at 1041 cm-1, characteristic for in-plane δ(CH) deformation in phenylalanine (Phe). Different sensitivity of mononuclear and leukemic cells to fixation was observed. While the 0.1 % concentration of GA was too low to preserve the cell structure for an extended period of time, a GA concentration of 0.5 % seemed optimal for both normal and malignant cells. Chemical changes in PBMCs samples stored for 11 days were also investigated, which manifested in numerous modifications in the secondary structure of proteins and the content of nucleic acids. The impact of cell preculturing for 72 h after unbanking was verified, and there was no significant effect on the molecular structure of cells fixed with 0.5 % GA. In summary, the developed protocol for the preparation of samples for Raman imaging allows for the effective differentiation of fixed normal leukocytes from malignant T lymphoblasts.

Successful Treatment of Large B-Cell Lymphoma in a Child with Compound Heterozygous Mutation in the ATM Gene.

Ataxia-telangiectasia (AT) is a multisystemic neurodegenerative inborn error of immunity (IEI) characterized by DNA repair defect, chromosomal instability, and hypersensitivity to ionizing radiation. Impaired DNA double-strand break repair determines a high risk of developing hematological malignancies, especially lymphoproliferative diseases. Poor response to treatment, excessive chemotherapy toxicities, and the need for avoiding exposure to ionizing radiation make the successful clinical management of patients with AT challenging for oncologists. We describe the favorable outcome of the LBCL with IRF4 rearrangement at stage III in a 7-year-old female patient diagnosed with AT. The patient was treated according to the B-HR arm of the INTER-B-NHL-COP 2010 protocol, including the administration of rituximab, cyclophosphamide, methotrexate, prednisone, etc. She presented excessive treatment toxicities despite individually reduced doses of methotrexate and cyclophosphamide. However, in the MRI there was no significant reduction in pathologic lymph nodes after three immunochemotherapy courses. Therefore, a lymph node biopsy was taken. Its subsequent histopathological examination revealed tuberculosis-like changes, though tuberculosis suspicion was excluded. After two following immunochemotherapy courses, PET-CT confirmed complete remission. From March 2022 onwards, the patient has remained in remission under the care of the outpatient children's oncology clinic.

The kinetics of blast clearance are associated with copy number alterations in childhood B-cell acute lymphoblastic leukemia.

We analyzed the pattern of whole-genome copy number alterations (CNAs) and their association with the kinetics of blast clearance during the induction treatment among 195 pediatric patients with B-cell precursor acute lymphoblastic leukemia (BCP-ALL) who displayed intermediate or high levels of minimal residual disease (MRD). Using unsupervised hierarchical clustering of CNAs > 5 Mbp, we dissected three clusters of leukemic samples with distinct kinetics of blast clearance [A - early slow responders (n=105), B - patients with persistent leukemia (n=24), C - fast responders with the low but detectable disease at the end of induction (n=66)] that corresponded with the patients' clinical features, the microdeletion profile,the presence of gene fusions and patients survival. Low incidence of large CNAs and chromosomal numerical aberrations occurred in cluster A which included ALL samples showing recurrent microdeletions within the genes encoding transcription factors (i.e., IKZF1, PAX5, ETV6, and ERG), DNA repair genes (XRCC3 and TOX), or harboring chromothriptic pattern of CNAs. Low hyperdiploid karyotype with trisomy 8 or hypodiploidy was predominantly observed in cluster B. Whereas cluster C included almost exclusively high-hyperdiploid ALL samples with concomitant mutations in RAS pathway genes. The pattern of CNAs influences the kinetics of leukemic cell clearance and selected aberrations affecting DNA repair genes may contribute to BCP-ALL chemoresistance.

Raman-based spectrophenotyping of the most important cells of the immune system.

INTRODUCTION: Human peripheral blood mononuclear cells (PBMCs) are a heterogeneous population of cells that includes T and B lymphocytes. The total number of lymphocytes and their percentage in the blood can be a marker for the diagnosis of several human diseases. Currently, cytometric methods are widely used to distinguish subtypes of leukocytes and quantify their number. These techniques use cell immunophenotyping, which is limited by the number of fluorochrome-labeled antibodies that can be applied simultaneously. OBJECTIVE: B and T lymphocytes were isolated from peripheral blood obtained from healthy human donors. METHODS: The immunomagnetic negative selection was used for the enrichment of B and T cells fractions, and their purity was assessed by flow cytometry. Isolated cells were fixed with 0.5% glutaraldehyde and measured using confocal Raman imaging. K-means cluster analysis, principal component analysis and partial least squares discriminant methods were applied for the identification of spectroscopic markers to distinguish B and T cells. HPLC was the reference method for identifying carotene in T cells. RESULTS: Reliable discrimination between T and B lymphocytes based on their spectral profile has been demonstrated using label-free Raman imaging and chemometric analysis. The presence of carotene in T lymphocytes (in addition to the previously reported in plasma) was confirmed and for the first time unequivocally identified as ß-carotene. In addition, the molecular features of the lymphocytes nuclei were found to support the discriminant analysis. It has been shown that although the presence of carotenoids in T cells depends on individual donor variability, the reliable differentiation between lymphocytes is possible based on Raman spectra collected from individual cells. CONCLUSIONS: This proves the potential of Raman spectroscopy in clinical diagnostics to automatically differentiate between cells that are an important component of our immune system.

Case report: Severe combined immunodeficiency with ligase 1 deficiency and Omenn-like manifestation.

DNA ligase I deficiency is an extremely rare primary immunodeficiency with only 6 patients reported in the literature. Most common manifestations include radiosensitivity, macrocytic anemia, lymphopenia with an increased percentage of gamma-delta T cells, and hypogammaglobulinemia requiring replacement therapy. Two-month-old girl with delayed development, T-B-NK+ SCID, and macrocytic anemia presented features of Omenn syndrome. Whole exome sequencing revealed two novel, heterozygous variants (c.2312 G>A, p.Arg771Gly and c.776+5G>T, p.Pro260*) in the LIG1 gene (NM_000234.1). Hematopoietic stem cell transplantation from a fully matched unrelated donor was performed at the age of 4 months using GEFA03 protocol. Mixed donor-recipient chimerism was observed, with 60-70% chimerism in the mononucleated cell compartment and over 90% in T-lymphocyte compartment, but autologous myeloid recovery. Stable CD4+ and CD8+ T-cell counts above 200/µL were achieved after 2 months, but the patient remained transfusion-dependent. Despite satisfactory immunological reconstitution, the second transplantation due to constitutional hemolytic defect has been considered. In light of possible re-transplantation, an issue of optimal conditioning protocol with sufficient myeloid engraftment is important. For the first time Omenn syndrome is described in a compound heterozygote carrying two the novel variants p.Arg771Gly and p.Pro260* in the LIG1 gene. Patients diagnosed with SCID and Omenn syndrome showing macrocytic anemia, should be screened for DNA ligase I deficiency.

Efficacy of ruxolitinib in acute lymphoblastic leukemia: A systematic review.

Philadelphia-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk molecular subtype with a gene expression profile similar to Philadelphia-positive ALL, but not harboring the BCR-ABL1 gene fusion. We aimed to investigate the efficacy of target therapy with the Janus kinase inhibitor, ruxolitinib, in patients with Ph-like ALL and molecular signature of JAK-STAT signaling pathway. A systematic search of the literature was performed to identify reports concerning administration of ruxolitinib in Ph-like ALL patients. Additionally, Polish Pediatric ALL registries were searched for patients with Ph-like ALL treated with ruxolitinib. Extracted information included epidemiological background, somatic aberrations, treatment response, and patient outcome. After PubMed database search, twelve patients were identified, and one was identified in the Polish Pediatric ALL registry. In nine patients gene fusions affecting JAK2 (n = 7) and EPOR (n = 2) were detected. Surface overexpression of CRLF2 and IKZF1 deletions were observed in two and three patients, respectively. Induction failure occurred in all the patients. Therapy with ruxolitinib led to complete (n = 7) and partial (n = 2) remission, in three individuals no information was found. Based on the limited number of studies describing the efficacy of ruxolitinib as an additional compound administrated with standard ALL therapy, we conclude that this approach can be considered in patients with aberrations activating JAK-STAT pathway.

Case report: Successful allogeneic stem cell transplantation in a child with novel GATA2 defect associated B-cell acute lymphoblastic leukemia.

GATA-binding protein 2 (GATA2) is a transcription factor responsible for the regulation of blood cell proliferation, differentiation, and maintenance in hematopoietic stem cells. Here, we describe successful bone marrow transplantation in a carrier of a novel GATA2 pathogenic variant who was diagnosed with immunodeficiency a few years after completion of B-cell precursor acute lymphoblastic leukemia (BCP-ALL) treatment. At the age of 4 years, the patient was diagnosed with and treated for BCP-ALL. Antileukemic therapy was complicated by pulmonary cryptococcosis. Two years after completion of the maintenance therapy, the child was consulted by an immunologist because of recurrent respiratory tract infections and an episode of sepsis. Flow cytometry revealed deep monocytopenia, lymphopenia, absence of B lymphocytes, considerably reduced NK cells, poor thymic T lymphocyte production, minor defects in T cell maturation, and absence of TCRγδ+ T cells. The presence of the likely pathogenic, heterozygous missense variant within exon 5 of GATA2 (NM_032638.5: c.1047T>G, Cys349Trp) was identified in the proband and confirmed in the father of the patient, who underwent allogeneic hematopoietic stem cell transplantation (HSCT) from a matched unrelated donor due to myelodysplastic syndrome with excess blasts at the age of 22 years. An allogeneic hematopoietic stem cell transplantation with a reduced toxicity conditioning protocol was performed using a matched sibling donor. Pre-transplant conditioning included fludarabine (5 × 30 mg/m2), treosulfan (3 × 14 g/m2), and thiotepa (10 mg/kg). Complete donor chimerism was achieved on post-transplant day 17. During the 12 months of the posttransplant observation period, she remained free from symptoms of acute or chronic graft-versus-host disease, and immunosuppressive treatment was therefore stopped. This is the second reported case of BCP-ALL in a patient with GATA2 deficiency, and the first successfully treated with a reduced-toxicity conditioning HSCT protocol. The co-occurrence of lymphoid malignancies and primary immunodeficiencies points to the role of genetic counseling and family screening for possible cancer predisposition syndromes prior to the selection of related HSCT donors.

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.