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Súhrn: Bolesti brucha patria medzi pomerne časté symptómy u adolescentov. Príčiny, ktoré sa podieľajú na bolestiach brucha, sú pestré a tým aj diferenciálna dia­gnostika je pomerne rozsiahla a zložitá. To súvisí pravdepodobne s tým, že brucho zaberá pomerne veľkú oblasť, obsahuje množstvo orgánov, štruktúr, systémov vrátane lymfatických uzlín, ktoré generalizovane reagujú na infekciu, či nádorové ochorenia. V našej kazuistike opisujeme prípad 17-ročného pacienta s náhlymi bolesťami brucha, chudnutím, vracaním a ikterom. V rámci diferenciálnej dia­gnostiky sa realizovali laboratórne a zobrazovacie vyšetrenia so zameraním na pankreas a hepatobiliárny trakt, kde sa zobrazila zväčšená hlava a chvost pankreasu, peripankreatická lymfadenopatia s vedľajším nálezom drobných ložísk na obličkách. V úvode sa suponovala skôr hereditárna pankreatitída a pseudotumory na obličkách, vzhľadom na vek pacienta bol menej pravdepodobný tumor pankreasu a metastázy. Definitívna dia­gnóza bola stanovená odberom bio­ptických vzoriek pankreasu pomocou endosonografického vyšetrenia. Histologický a cytologický nález preukázal prítomnosť lymfocytárnych blastických buniek, charakteru CD20+ B-NHL, konštatovaný difúzny veľkobunkový B-lymfóm pankreasu (DLBCL – diffuse large B cell lymphoma). Staging ochorenia nepreukázal inflitráciu malígnych buniek v kostnej dreni a centrálnej nervovej sústave. Promptne stanovená dia­gnóza a podaná príslušná onkologická liečba (chemoterapia v kombinácii s monoklonálnou protilátkou) zabezpečila pacientovi návrat do každodenného života a je nevyhnutným predpokladom priaznivej prognózy pacienta. Kľúčové slová: bolesti brucha – žltačka – difúzny veľkobunkový B-lymfóm

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INTRODUCTION: Since the beginning of COVID-19 pandemic, it is known that the severe course of the disease occurs mostly among the elderly, whereas it is rare among children and young adults. Comorbidities, in particular, diabetes and hypertension, clearly associated with age, besides obesity and smoke, are strongly associated with the need for intensive treatment and a dismal outcome. A weaker immunity of the elderly has been proposed as a possible explanation of this uneven age distribution. Thus, there is concern that children treated for cancer may allso be at risk for an unfavourable course of infection. Along the same line, anecdotal information from Wuhan, China, mentioned a severe course of COVID-19 in a child treated for leukaemia. AIM AND METHODS: We made a flash survey on COVID-19 incidence and severity among children on anticancer treatment. Respondents were asked by email to fill in a short Web-based survey. RESULTS: We received reports from 25 countries, where approximately 10,000 patients at risk are followed up. At the time of the survey, more than 200 of these children were tested, nine of whom were positive for COVID-19. Eight of the nine cases had asymptomatic to mild disease, and one was just diagnosed with COVID-19. We also discuss preventive measures that are in place or should be taken and treatment options in immunocompromised children with COVID-19. CONCLUSION: Thus, even children receiving anticancer chemotherapy may have a mild or asymptomatic course of COVID-19. While we should not underestimate the risk of developing a more severe course of COVID-19 than that observed here, the intensity of preventive measures should not cause delays or obstructions in oncological treatment.

PURPOSE Off-label use of vemurafenib (VMF) to treat BRAFV600E mutation–positive, refractory, childhood Langerhans cell histiocytosis (LCH) was evaluated. PATIENTS AND METHODS Fifty-four patients from 12 countries took VMF 20 mg/kg/d. They were classified according to risk organ involvement: liver, spleen, and/or blood cytopenia. The main evaluation criteria were adverse events (Common Terminology Criteria for Adverse Events [version 4.3]) and therapeutic responses according to Disease Activity Score. RESULTS LCH extent was distributed as follows: 44 with positive and 10 with negative risk organ involvement. Median age at diagnosis was 0.9 years (range, 0.1 to 6.5 years). Median age at VMF initiation was 1.8 years (range, 0.18 to 14 years), with a median follow-up of 22 months (range, 4.3 to 57 months), whereas median treatment duration was 13.9 months (for 855 patient-months). At 8 weeks, 38 complete responses and 16 partial responses had been achieved, with the median Disease Activity Score decreasing from 7 at diagnosis to 0 ( P < .001). Skin rash, the most frequent adverse event, affected 74% of patients. No secondary skin cancer was observed. Therapeutic plasma VMF concentrations (range, 10 to 20 mg/L) seemed to be safe and effective. VMF discontinuation for 30 patients led to 24 LCH reactivations. The blood BRAFV600E allele load, assessed as circulating cell-free DNA, decreased after starting VMF but remained positive (median, 3.6% at diagnosis, and 1.6% during VMF treatment; P < .001) and was associated with a higher risk of reactivation at VMF discontinuation. None of the various empirical therapies (hematopoietic stem-cell transplantation, cladribine and cytarabine, anti-MEK agent, vinblastine, etc) used for maintenance could eradicate the BRAFV600E clone. CONCLUSION VMF seemed safe and effective in children with refractory BRAFV600E-positive LCH. Additional studies are needed to find effective maintenance therapy approaches.

Pleuropulmonary blastoma (PPB) is a rare cancer occurring mainly during early childhood and often associated with germline DICER1 mutations. It is classified by the macroscopic appearance into three interrelated clinico-pathologic entities on a developmental continuum. Complete tumor resection is a main prognostic factor and can be performed at diagnosis or after neoadjuvant treatment that includes chemotherapy and in some cases radiotherapy. Optimal modalities of neo- or adjuvant treatments can be challenging taking into account potential long-term toxicities in this young population. This paper presents the recommendations for diagnosis and treatment of children and adolescents with PPB elaborated by the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) within the European Union-funded project PARTNER (Paediatric Rare Tumours Network - European Registry).

Pancreatoblastoma (PBL) is a rare malignant epithelial neoplasm affecting typically young children. Signs related to advanced upper-abdominal tumor accompanied by elevated serum α-fetoprotein levels in a young child suggest PBL, however histopathological examination is required for diagnosis. The mainstay of treatment is a complete surgical resection. Inoperable and/or metastatic PBL may become amenable to complete, delayed surgery after neo-adjuvant chemotherapy. This manuscript presents the internationally consensus recommendations for the diagnosis and treatment of children with PBL, established by the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) within the EU-funded PARTNER (Paediatric Rare Tumors Network – European Registry) project.

Background Neuroblastoma is the most common extracranial solid tumour of childhood with extremely heterogeneous bio-logical and clinical behaviour. Despite advances in its treatment, the long-term prognosis of patients with a high-risk and relapsed neuroblastoma remains poor. The implementation of immunotherapy into the treatment protocols has the potential to improve it. Dinutuximab, a chimeric monoclonal antibody, leads to the apoptosis of tumour cells through binding to the GD2 receptor. The article aim is to present the first experience of our centre with dinutuximab treatment. Patients and methods In 2018-2019, we administered 31 cycles of dinutuximab to seven patients. Five patients with high-risk neuroblastoma received dinutuximab in the first line, in two patients with relapse, dinutuximab was administered in the second line of treatment. To evaluate the toxicity of the treatment, the nursing records of patients during immunotherapy were retrospectively analysed. Results Two patients treated with dinutuximab in the first line are in complete remission, three patients achieved a partial response. Both patients with relapsed neuroblastoma were dia-gnosed with a second relapse after immunotherapy and died of disease progression. The treatment tolerance was acceptable in most patients - in six patients adverse events were managed with adequate supportive care. These were mainly symptoms of capillary leak syndrome, pain and hypersensitivity reactions. In one patient, the treatment was discontinued due to severe neurotoxicity. Conclusion Dinutuximab has a proven benefit in the eradication of the minimal residual disease in the treatment of neuroblastoma. Immunotherapy is currently the standard for first-line treatment of high-risk neuroblastoma. Its role in the treatment of relapsed neuroblastoma is a subject of several ongoing studies as well as the optimization of therapeutic regimens. Dinutuximab administration is associated with a considerable risk of severe adverse reactions, so the treatment belongs to the hands of an experienced paediatric oncology centre.

Background: Based on previous retrospective results, we investigated the association of coagulation FXIII subunit A (FXIII-A) expression pattern on survival and correlations with known prognostic factors of B-cell progenitor (BCP) childhood acute lymphoblastic leukemia (ALL) as a pilot study of the prospective multi-center BFM ALL-IC 2009 clinical trial. Methods: The study included four national centers (n = 408). Immunophenotyping by flow cytometry and cytogenetic analysis were performed by standard methods. Copy number alteration was studied in a subset of patients (n = 59). Survival rates were estimated by Kaplan-Meier analysis. Correlations between FXIII-A expression patterns and risk factors were investigated with Cox and logistic regression models. Results: Three different patterns of FXIII-A expression were observed: negative (&lt, 20%), dim (20&ndash, 79%), and bright (&ge, 80%). The FXIII-A dim expression group had significantly higher 5-year event-free survival (EFS) (93%) than the FXIII-A negative (70%) and FXIII-A bright (61%) groups. Distribution of intermediate genetic risk categories and the &ldquo, B-other&rdquo, genetic subgroup differed significantly between the FXIII-A positive and negative groups. Multivariate logistic regression confirmed independent association between the FXIII-A negative expression characteristics and the prevalence of intermediate genetic risk group. Conclusions: FXIII-A negativity is associated with dismal survival in children with BCP-ALL and is an indicator for the presence of unfavorable genetic alterations.

Background Invasive fungal infections are a life-threatening complication of cancer treatments, especially in hemato-oncological patients. Mucormycosis is the third leading cause of invasive fungal infections after Aspergillus and Candida infections. The first clinical symptoms are usually non-specific, which can lead to a late diagnosis and delayed therapy. Purpose The objective of this report is to summarize data in the literature about mucormycosis and to present a case report of a patient with acute lymphoblastic leukemia, who developed this infection at our center. Risk factors for the development of mucormycosis, clinical symptoms, radiology, laboratory results, and outcome were retrospectively evaluated. Case We describe a 6-years-old female patient with acute lymphoblastic leukemia. During the induction phase of therapy, the patient developed febrile neutropenia and did not respond to therapy with a combination of antibiotics and supportive treatment. Pansinusitis and orbitocellulitis developed. Examination of the biological material revealed that the etiological agent was a Rhizopus sp. The patient was treated with a combination of antimycotic drugs, but the infection disseminated to the central nervous system. She underwent radical surgical resection of the affected tissue. At this time, she is still under treatment with antimycotic and oncology agents, but is in remission of the main diagnosis and in good clinical condition. Conclusion Mucormycosis is an invasive fungal infection with high morbidity and mortality. Early diagnosis and initiation of effective therapy using a combination of amphotericin B administration and surgery are necessary to obtain a favorable outcome. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.

The first event in origination of many childhood leukemias is a specific preleukemic fusion gene (PFG) that arises, often in utero, in hematopoietic stem/progenitor cells (HSPC) from misrepaired DNA double strand break (DSB). An immanently elevated level of DSB and impaired apoptosis may contribute to origination and persistence of PFG and donor cell-derived leukemia in recipients of allogeneic transplantation of umbilical cord blood (UCB). We investigated DSB, apoptosis and PFG in the backtracked UCB cells of leukemic patients. RNA from UCB of three patients with acute lymphoblastic leukemia, patient with acute megakaryoblastic leukemia and Down syndrome, and four healthy children was screened for common PFG by RT-qPCR. Presence of PFG was validated by sequencing. Endogenous γH2AX and 53BP1 DNA repair foci, cell populations, and apoptosis were analyzed in UCB CD34+/- cells with imaging and standard flow cytometry. We found MLL2-AF4 and BCR-ABL (p190) fusion genes in UCB of two out from four pediatric patients, apparently not detected at diagnosis, while UCB cells of TEL-AML1+ ALL patient were tested negative for this PFG and no PFG were detected in UCB cells of healthy children. No significant difference in DNA damage and apoptosis between UCB CD34+/- cells from healthy children and leukemic patients was observed, while Down syndrome trisomy increased DNA damage and resulted in distribution of cell populations resembling transient abnormal myelopoiesis. Our findings indicate increased genetic instability in UCB HSPC of leukemic patients and may be potentially used for diagnostics and exclusion of possibly affected UCB from transplantation.

Background Pediatric oncologists are often faced with situations in which parents or guardians refuse recommended treatment for curable childhood cancer. Deciding how to proceed in such situations is an ethical dilemma. The aim of this article is to consider optimal approaches when parents are strongly against oncological treatment, potentially compromising their childrens rights for health care and to the chance for cure. Cases In this paper, we report two cases of treatment refusal from our department and the impact of such decisions on the children themselves. Case no. 1 describes a child with retinoblastoma whose parents refused standard treatment in order to seek alternative treatment abroad. Case no. 2 describes a patient with a primary lymphoma of bone who received treatment by a court order after parental refusal. Conclusion When parents refuse a treatment for potentially curable cancer, the medical team often focuses on the certainty of death without treatment. In the background, there is a smaller but still significant risk that - even if the treatment is eventually accepted or compelled - the child will still die from treatment-related complications or refractory disease, possibly with considerable suffering. The reasons for refusing a treatment vary. The entire medical team is tasked with trying to respectfully understand the reasoning behind the parents unwillingness to accept the treatment, in order to address all possible misunderstandings and to propose solutions that could be acceptable for the parents. In some situations however, it is necessary to resolve the dilemma by legal means in order to protect the life of the child.Key words: oncology - ethics - decision making - treatment refusal - legal guardians The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 7. 8. 2017Accepted: 7. 9. 2017.

Acute lymphoblastic leukemia (ALL) belongs to a genetically heterogeneous disease associated with a wide range of chromosomal and molecular changes. Determining these changes at the time of diagnosis can help the therapeutic decision, and contributes to the prediction of patients' clinical outcomes. A part of B-ALL (B-other) lacks cytogenetic abnormalities with clinical relevance for prognosis. Our first goal was to retrospectively review genetic results of patients from 2013-2017 and identify number of B-other patients in Slovak population. The second goal was to implement single nucleotide polymorphism (SNP) array analysis to improve the diagnosis and risk stratification. In this study we reviewed 133 B-ALL patients. We found that nearly 40% of them (52 cases) belonged to the B-other ALL group. Eighteen B-other ALL patients were subjected to the analysis using SNP-array. Overall, we identified 126 cytogenomic changes and in 4 patients the SNP array revealed clinically relevant markers of adverse prognosis and high relapse risk. Integrating identified genetic changes into clinical practice can bring improvement of prognosis assessment for children with ALL in Slovakia.

Juvenile myelomonocytic leukemia (JMML) is a rare, aggressive clonal myeloproliferative disorder of infancy and early childhood caused by oncogenic mutations in genes involved in the Ras pathway. Long-term survival has only been achieved with hematopoietic stem cell transplantation (HSCT), being able to cure more than 50% patients. To manage the disease before HSCT remains an important issue with constant searching for optimal treatment modalities. According to several retrospective analyses, azacitidine (AZA) induced clinical and molecular responses in patients with relapsed JMML pre-transplant and post-transplant, suggesting its use as a promising "bridging" therapy before HSCT. In this paper we report our first consecutive cohort of patients with JMML treated at our institution as well as our experience with the diagnosis, novel treatment and management of these patients before the HSCT. We present 6 patients with JMML, harboring different somatic mutations (PTPN11 and NRAS), with distinct clinical features; 3 of them had been treated with AZA 75 mg/m2 i.v. on days 1 to 7 of a 28-day cycle before the HSCT. Response to therapy was evaluated after each cycle in accordance with the International response criteria. One patient had a progression of splenomegaly during the treatment and after three cycles he was urgently transplanted. At the present, he is remaining in complete remission 3 years after HSCT. Two patients showed impressive response following the first cycle of the therapy with a regression of splenomegaly and monocyte count, normalized leukocytes, platelets and absent blasts in peripheral blood. The treatment was well tolerated with no adverse effect recorded. The clinical activity and favorable toxicity of AZA in JMML provide a rationale for its use as a "bridging" therapy before HSCT. Prospective trials with accompanying translational studies are required to provide further information regarding individual factors that may direct the most appropriate choice of pretransplantation therapy.

The article presents the results of a study of life meanings and values in connection with the life satisfaction of persons with drug addiction at the stage of rehabilitation. The urgency of the problem is determined by the fact that the statistics provided by the UN confirm that the number of people who use drugs is steadily increasing every year. In this regard, the issues of prevention of drug addiction and rehabilitation of addicts for the Russian society are today the most acute and represent a global problem. The results obtained in the study state that for drug addicts at the stage of rehabilitation, they begin to have a meaningful attitude to their life, positively assess the life path they have passed and the experience gained, considering it the beginning of a new stage in life, and make plans for the future. This fact may indicate the productivity of the rehabilitation program. They do not think about how much life in general is subject to control on their part. The respondents attach value to the very living of life, feel the need to be able to feel love in all its manifestations. Status and altruistic meanings are of the least importance in the respondents' system of life meanings. Hedonistic meanings of life prevail, acceptance of life as it is. Also, statistically significant relationships were found between the components of life meanings and values and the components of life satisfaction in drug addicts.

The Last decades have witnessed elevated tension and conflicts in young people’s environment. There has been an increase in crime, terrorism, suicides, addictions, and other behavioral deviations among the young. Up to the 21st century, hostility was equated with aggression in its broad, non-differentiated sense. Today hostility is considered to be an inflexible and complex personality trait. Recent studies show that several genes can be viewed as genetic predictors of aggressiveness and hostility (Rodríguez-Ramos Á., Et al., 2019; Tkachenko O.N., 2016). The paper investigates the relationship between genotype and ethnicity as predisposing factors in manifesting hostile behavior. The study involved 320 participants - adolescents and young men of different ethnicity (Russians, Armenians, Dagestanis, Kabardians), aged from 12 to 19. Research methods: Buss-Durkee Hostility inventory (in the adaptation of Osnitsky A.K., 1998); isolation genomic DNA from buccal epithelial cells. Genotypes and alleles of the monoamine oxidase enzyme (MAOA) gene were considered as a candidate gene. Statistical analysis and data processing were performed using the PSPP 0.8 5. It was established that the low-active variant of the MAOA monoamine oxidase A gene (LPR) plays a significant role in determining the risk of hostile behavior. As far as the ethnic factor is concerned, low-level MAOA variants have significant differences in the populations of Russians compared with Dagestanis, or Kabardians. The results received contribute to understanding the relationships between genetics and behavior. It will help develop effective methods for the prevention of aggressive and hostile behavioral patterns.

Langerhans cell histiocytosis (LCH) is a histiocytic disorder driven by a constitutive activation of the MAPK signaling pathway in myeloid cells. In 50–60% of cases, it is caused by the BRAFV600E mutation. There is evidence that levels of BRAFV600E in the peripheral blood of patients with LCH correlate with disease burden and could be used as marker for disease extent and response to therapy. However, there is currently no consensus on how testing for minimal disseminated disease should be performed. Different approaches to determine the mutation load in patients with LCH were assessed and longitudinal evaluation of patient DNA during treatment with chemotherapy and/or the RAF inhibitor vemurafenib was performed. DNA was isolated from whole blood, different leukocyte subsets, and circulating cell-free DNA (ccf-DNA). We show that determining BRAF levels from whole blood is superior to using ccfDNA. Furthermore, it is important to identify the clinically relevant BRAF-mutated cellular subpopulations such as CD14+ monocytes or CD1c+ DCs, since other blood cells can also harbor the mutation and therefore confound whole blood or ccfDNA measurements. Our data support the view that single-agent treatment with an RAF inhibitor reduces disease activity but does not cure LCH.

Despite attempts to improve the definitions of ambiguous lineage leukemia (ALAL) during the last 2 decades, general therapy recommendations are missing. Herein, we report a large cohort of children with ALAL and propose a treatment strategy. A retrospective multinational study (International Berlin-Frankfurt-Munster Study of Leukemias of Ambiguous Lineage [iBFM-AMBI2012]) of 233 cases of pediatric ALAL patients is presented. Survival statistics were used to compare the prognosis of subsets and types of treatment. Five-year event-free survival (EFS) of patients with acute lymphoblastic leukemia (ALL)-type primary therapy (80% ± 4%) was superior to that of children who received acute myeloid leukemia (AML)-type or combined-type treatment (36% ± 7.2% and 50% ± 12%, respectively). When ALL- or AML-specific gene fusions were excluded, 5-year EFS of CD19+ leukemia was 83% ± 5.3% on ALL-type primary treatment compared with 0% ± 0% and 28% ± 14% on AML-type and combined-type primary treatment, respectively. Superiority of ALL-type treatment was documented in single-population mixed phenotype ALAL (using World Health Organization and/or European Group for Immunophenotyping of Leukemia definitions) and bilineal ALAL. Treatment with ALL-type protocols is recommended for the majority of pediatric patients with ALAL, including cases with CD19+ ALAL. AML-type treatment is preferred in a minority of ALAL cases with CD19- and no other lymphoid features. No overall benefit of transplantation was documented, and it could be introduced in some patients with a poor response to treatment. As no clear indicator was found for a change in treatment type, this is to be considered only in cases with ≥5% blasts after remission induction. The results provide a basis for a prospective trial.

The clinical characteristics of chronic myeloid leukemia (CML) in lymphoid blast crisis (BC) can resemble those of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph ALL). Because of this, there can be concern as to whether a patient with newly diagnosed Ph leukemia has Ph ALL or CML in lymphoid BC. This distinction has significant potential therapeutic implications because most children with Ph ALL are now treated with chemotherapy plus a tyrosine kinase inhibitor, whereas allogeneic stem cell transplant is usually recommended for any patient with CML that presents in or later develops BC.

Introduction. Exophiala dermatitidisis a relatively common environmental black yeast with worldwide distribution and is a rare cause of fungal infection, mostly in patients with certain predisposing factors. Due to the rarity of the infection, little is known about the specific predisposing factors, way of infection or treatment. Case presentation. Here, we report what is to our knowledge the first case of E. dermatitidis infection in a child after allogeneic stem cell transplantation. We also review all paediatric cases reported in the literature since 1993. Conclusion. This is, to our knowledge, the first reported case of E. dermatitidis infection in a child after allogeneic stem cell transplantation. This report should increase the awareness of E. dermatitidis in immunocompromised paediatric patients, particularly after stem cell transplantation.

Magnusiomyces capitatus (previously known as Geotrichum capitatum or Blastoschizomyces capitatus or Trichosporon capitatum) is a rare cause of fungal infection in immunocompromised patients. Most of these cases (87%) have been reported from the Mediterranean region, as it is extremely rare to recognize it in other regions. Here we report a first case of disseminated M. capitatus infection in Slovakia. The patient – 19 year old woman with myelodysplastic syndrome was diagnosed with M. capitatus fungemia after allogeneic stem cell transplantation. The infection occurred despite antifungal prophylaxis with micafungin, which was in vitro sensitive to the yeast. The treatment according to minimal inhibitory concentrations (micafungin, voriconazol) and granulocyte transfusions were administered. M. capitatus was cleared out from the bloodstream. However, patient died of multiple organ failure. Autopsy showed multiple lesions in organs, but did not prove presence of yeast by histopathology. M. capitatus was confirmed by polymerase chain reaction from all tested organs: heart, brain, lungs, spleen, liver and kidneys. We present the post mortem pictures showing the yeast lesions in affected organs. 2012 Elsevier Ltd. All rights reserved.

Key Points Single-agent vemurafenib leads to a rapid and sustained clinical response in severe multisystem LCH but does not eradicate the disease. Longitudinal assessment of BRAF V600E during treatment shows that clinical remission can occur despite significant amounts of mutated BRAF.

The precise diagnosis of acute lymphoblastic leukemia is essential for correct prognosis assessment and therapy regimen selection. At present, immunophenotyping, cytogenetics and molecular screening are major and complementary methods utilized in a routine leukemia diagnostics. The aim of this study was to validate the application of multiplex reverse transcription-polymerase chain reaction (RT-PCR) assay for molecular diagnosis of the most common pediatric acute lymphoblastic leukemia-associated fusion transcripts. Our data show that screening of bone marrow and/or peripheral blood by RT-PCR, consisting of multiplex and monoplex PCR, confirmed results of real-time quantitative PCR (RT qPCR). This screening may provide a reliable, specific and sensitive method amenable to standard laboratory practice and a cost-effective alternative to more complex and expensive RT qPCR techniques.

BACKGROUND: Low grade gliomas (LGG) are the most frequent tumors of the central nervous system in children. Pediatric LGG are a heterogeneous set of tumors. They encompass tumors of astrocytic, oligodendroglial, and mixed glial-neuronal histology, and are classified according to the World Health Organization (WHO). METHODS: The objective of our study was to analyze the outcome of patients with LGG from the Department of Pediatric Hematology and Oncology in Bratislava, Slovakia treated in period from January 2000 up to December 2015. The cohort consisted of 139 patients with LGG, 83 boys/56 girls. RESULTS: The most common histological type was pilocytic astrocytoma (WHO grade I) in 64 children. Primary surgery was performed in 102 children and 72 from these do not need any further therapy. Forty eight patients received chemotherapy first or other line therapy. Radiotherapy was used 26 times. In our study median follow up was 82,3 months and overall survival for the whole cohort was 97,2%. CONCLUSION: In pediatric low grade glioma surgery is the mainstay of therapy. Ten year overall survival rates for patients whose tumors are completely resected are 90% or greater. Chemotherapy is reserved for progressive or recurrent tumors. Radiotherapy can also improve OS but is associated with more frequent adverse effects. Recent advent of integrated genomics and NGS has implicated the activation of RAS/RAF/MEK pathway in tumor genesis of LGG. Many of these biological advances are changing treatment paradigma, particularly in low-grade gliomas, where rationale targeted therapies are currently being explored in clinical trials.

Background The classification of acute myeloid leukemia (AML) FAB subtype M7 relies on immunophenotypic assessment. CD41 is expressed throughout all stages of maturation of megakaryocytes and has therefore been described as a specific blast cell marker in AML M7 as well as in transient myeloproliferative disease (TMD) of patients with Down syndrome (DS). However, technical difficulties underlie the need for new markers for these entities. Methods We evaluated the expression of human lymphocyte function-associated antigen 1 (CD11a) in a large cohort of pediatric AML and TMD patients (n = 91) of the Austrian AML-BFM 98 and 2004 studies. Results We found a consistent deficiency of CD11a as assessed by mean fluorescence intensity in all patients with non-DS AML M7 (n = 8) and M6 (n = 1), all cases of classical DS-AML (n = 12) as well as TMD (n = 15) that was statistically significant in comparison to non-DS AML M0-M5 patients (n = 55; P < 0.001, sensitivity 100%). Only three of 55 Non-DS M0-5 patients were CD11a deficient (specificity 95%). Monocytic leukemias (M4/5) and normal monocytes typically showed a high CD11a expression, FAB types M1/2 and normal neutrophils an intermediate expression level, while all M3 leukemias were rather low in CD11a expression. Conclusions We conclude, that deficiency of CD11a expression should be added to the diagnostic criteria of AML-M7, classical DS-AML and TMD. © 2013 International Clinical Cytometry Society

Background Acute myeloid leukemia (AML) in children is rare, and it is generally considered to be more resistant to chemotherapy than acute lymphoblastic leukemia. However, because of the gradual intensification of chemotherapy and better supportive care, outcomes have improved considerably over the past 20 years. The management of children with AML in the Slovak Republic was unified and centralized during the second half of the 1990s with the introduction of Berlin-Frankfurt-Munster (BFM) protocols. In 2000, the AML-BFM-1998 protocol was introduced, and data collection became centralized.

Bacterial infection is the most common complication in paediatric oncological patients during cancer treatment. A suitable tool for early prediction of unfavourable course of infection is still needed. We performed a prospective longitudinal observational study to evaluate of the role of serum biomarkers (C-reactive protein, procalcitonin, interleukin-6, presepsin) in the early diagnosis of bacteraemia (gram-negative versus gram-positive) in patients with haematological malignancies. We observed 69 febrile episodes in 33 patients (17 male, 16 female; 1.5-18.9 years, mean 7.31 years, median 5 years). Within this sample, there were 22 cases of positive blood cultures, 16 cases of sepsis, 38 cases of fever with no signs or symptoms of sepsis, and two deaths from infectious complications. All markers tested had good negative predictive value (73% - 93%). CRP was characterized by good specificity for registration bacteraemia (96%, 95% CI: 85% - 99%), but other results were inconclusive. We identified comparably balanced sensitivity (64% - 81%) and specificity (61% - 88%) for interleukin-6 and procalcitonin, and we proved their quality to predict positive blood culture and clinical signs of sepsis as well. Patients with gram-negative bacteraemia had significantly elevated levels of PCT and IL-6 in comparison with a group of patients with gram-positive bacteraemia (p = 0.04 for PCT and p = 0.005 for IL-6). Presepsin was characterized by poor specificity (27%, 95% CI: 15% - 43%) and positive predictive value (24%, 95% CI: 12 - 39%) for predicting bacteraemia, and by better sensitivity (84%, 95% CI: 55% - 98%) and specificity (58%, 95% CI: 42% - 73%) for predicting clinical signs of sepsis.

Children with Down syndrome (DS) up to the age of 4 years are at a 150-fold excess risk of developing myeloid leukemia (ML-DS). Approximately 4%-5% of newborns with DS develop transient myeloproliferative disorder (TMD). Blast cell structure and immunophenotype are similar in TMD and ML-DS. A mutation in the hematopoietic transcription factor GATA1 is present in almost all cases. Here, we show that simple techniques detect GATA1 mutations in the largest series of TMD (n = 134; 88%) and ML-DS (n = 103; 85%) cases tested. Furthermore, no significant difference in the mutational spectrum between the 2 disorders was seen. Thus, the type of GATA1 sequence mutation is not a reliable tool and is not prognostic of which patients with TMD are probable to develop ML-DS.

Research has exposed cancer to be a heterogeneous disease with a high degree of inter-tumoral and intra-tumoral variability. Individual tumors have unique profiles, and these molecular signatures make the use of traditional histology-based treatments problematic. The conventional diagnostic categories, while necessary for care, thwart the use of molecular information for treatment as molecular characteristics cross tissue types. This is compounded by the struggle to keep abreast the scientific advances made in all fields of science, and by the enormous challenge to organize, cross-reference, and apply molecular data for patient benefit. In order to supplement the site-specific, histology-driven diagnosis with genomic, proteomic and metabolomics information, a paradigm shift in diagnosis and treatment of patients is required. While most physicians are open and keen to use the emerging data for therapy, even those versed in molecular therapeutics are overwhelmed with the amount of available data. It is not surprising that even though The Human Genome Project was completed thirteen years ago, our patients have not benefited from the information. Physicians cannot, and should not be asked to process the gigabytes of genomic and proteomic information on their own in order to provide patients with safe therapies. The following consensus summary identifies the needed for practice changes, proposes potential solutions to the present crisis of informational overload, suggests ways of providing physicians with the tools necessary for interpreting patient specific molecular profiles, and facilitates the implementation of quantitative precision medicine. It also provides two case studies where this approach has been used.

Treatment of childhood acute lymphoblastic leukemia (ALL) according to the 1st Slovak protocol started in the Slovak Republic in 1971 in eight pediatric departments. Gradually, two other protocols were written, and 496 children were treated with these three protocols from 1971 to 1992. Since 1992, all children have been treated in three pediatric oncological departments. From 1992 to 1996, protocols for standard and high-risk ALL were developed that were used for 111 children in Bratislava, while the centres in Banska Bystrica and Kosice had started to use BFM protocols. Since 1997, all patients with ALL have been treated according to ALL BFM 95, and since 2002, they have been included in the ALL IC BFM 2002 study. We evaluated treatment results in the standard arm of ALL BFM 95 and compared it with previous Slovak protocols. Rates of complete remission increased from 90.6% in the first Slovak protocol to 97.1% in BFM 95; EFS and OS increased from 0.46 and 0.50 to 0.67 and 0.72, respectively. Relapse rates decreased from 42% to 20.5%. EFS was significantly worse in children with leukocyte counts >100×109/l and in the HR group in comparison to standard- and medium-risk groups. OS was also significantly worse in T-cell ALL than in B-cell ALL. Death rates in the 1st complete remission decreased gradually in the Slovak protocols from 10.4% to 1.8%, but were high in BFM 95 (10.8%) due to more intensive therapy and initial unsatisfactory experiences with BFM protocols. All parameters improved in the ALL IC BFM 2002 study.

Introduction: Subunit A of blood coagulation factor XIII (FXIIIA) may be expressed in leukemic B-cell precursor (BCP) lymphoblasts in addition to platelets, megakaryocytes, monocytes and macrophages (Kiss F. et al Thromb Haemost 2006;96:172-82.). In a retrospective single-center cohort of children with acute lymphoblastic leukemia (ALL) treated with the BFM ALL-IC 2002 protocol, expression of FXIIIA was correlated with statistically significant survival advantage (Kárai B et al. Pathol Oncol Res 2018; 24:345-52.). Our aim was to investigate the impact of FXIIIA expression pattern on EFS and its correlation with known clinical and genetic prognostic factors in a multi-center pilot study within the frames of the BFM ALL-IC 2009 clinical trial (EuDract: 2010-019722-13). Patients and Methods: We examined 317 children with BCP-ALL between 2011 and 2018 at institutions in Poland (n=188), Hungary (n=116), and Slovakia (n=13). Patients with Down-syndrome, t(9;22), and infants ( Results: We observed 3 different patterns of FXIIIA expression in leukemic lymphoblasts: negative pattern (80%). Evaluation of FC histograms of the moderate positive pattern showed that FXIIIA expression increased continuously which excluded the existence of distinct FXIIIA negative and FXIIIA positive subpopulations within the moderate positive expression group (Fig.1). In contrast to the previous single-center retrospective cohort, EFS of patients with FXIIIA positive BCP-ALL was not significantly different from that of patients of FXIIIA negative BCP-ALL (Fig.2A). However, a significant EFS advantage of patients with moderate FXIIIA positivity was demonstrated when compared with patients with FXIIIA negative BCP-ALL (p=0.019), and with patients with FXIIIA strong positive BCP-ALL (p=0.001) (Fig.2B). The 3 different FXIIIA expression patterns did not correlate significantly with either risk stratification according to BFM ALL-IC 2009 or FC MRD categories. Intermediate genetic risk categories (low hyperdiploidy, t(1;19), and "B-other") were significantly more prevalent (p=0.042) among patients with FXIIIA negative BCP-ALL than among patients with strong FXIIIA positive BCP-ALL. The "B-other" subgroup was also significantly more prevalent (p=0.022) among patients of the above 2 groups (Table 1). Distribution of the "B-other" genetic group and the prednisone response differed significantly between the FXIIIA positive and negative groups. Intermediate genetic risk group is mostly made up of patients assigned to the "B-other" group explaining the significant difference between the FXIIIA positive and negative groups, in terms that FXIIIA negative patients had 50% lower chance of facing low instead of intermediate genetic risk compared to FXIIIA positive patients. The multivariate logistic regression analysis confirmed the association between the FXIIIA characteristics and the intermediate genetic risk group. This association persisted after adjusting for categorical variables, i.e. gender, age, WBC, and BFM ALL-IC 2009 stratification (Table 2). High risk copy number alterations were detected in 4/7 samples of the FXIIIA negative group and in 1/17 of the FXIIIA positive group. Conclusions: FXIIIA expression status of leukemic lymphoblasts can easily be determined by FC. Patients with FXIIIA negative lymphoblasts should be further investigated with sophisticated and more expensive genetic and molecular methods. Grant sponsor: OTKA K108885. Disclosures No relevant conflicts of interest to declare.

Our aim was to analyze event-free (EFS) and overall survival (OS) among children and adolescents with acute lymphoblastic leukemia (ALL) treated with International BFM Intercontinental trial (ALL IC 2002) therapy in the Slovak Republic. In total, 280 children and adolescent age 1 to 18 years were treated with ALL IC BFM 2002 based therapy from 2002 to 2012, which was divided into two periods. During 2002-2007, when patients were actively enrolled in the ALL IC-BFM 2002 trial, and during 2008-2012 when the trial was closed and patients were treated with the same therapy without randomization. Five-year EFS and OS rates were 79% (+/- 2.6%) and 86% (+/- 2.1%), respectively, similar to results obtained in the ALL-BFM 95 trial, which was the basis for ALL IC BFM 2002 therapy. The EFS (p

Chromosomal rearrangements of the human MLL (mixed lineage leukemia) gene are associated with high-risk infant, pediatric, adult and therapy-induced acute leukemias. We used long-distance inverse-polymerase chain reaction to characterize the chromosomal rearrangement of individual acute leukemia patients. We present data of the molecular characterization of 1590 MLL-rearranged biopsy samples obtained from acute leukemia patients. The precise localization of genomic breakpoints within the MLL gene and the involved translocation partner genes (TPGs) were determined and novel TPGs identified. All patients were classified according to their gender (852 females and 745 males), age at diagnosis (558 infant, 416 pediatric and 616 adult leukemia patients) and other clinical criteria. Combined data of our study and recently published data revealed a total of 121 different MLL rearrangements, of which 79 TPGs are now characterized at the molecular level. However, only seven rearrangements seem to be predominantly associated with illegitimate recombinations of the MLL gene (≈ 90%): AFF1/AF4, MLLT3/AF9, MLLT1/ENL, MLLT10/AF10, ELL, partial tandem duplications (MLL PTDs) and MLLT4/AF6, respectively. The MLL breakpoint distributions for all clinical relevant subtypes (gender, disease type, age at diagnosis, reciprocal, complex and therapy-induced translocations) are presented. Finally, we present the extending network of reciprocal MLL fusions deriving from complex rearrangements.

Mutations of the hematopoietic transcription factor GATA1 (GATA1s) are pathognomonic in newborn with transient leukemia and children with Down syndrome and myeloid leukemia (ML-DS). Both TL and ML-DS can also occur in children with trisomy 21 mosaic.Between 2002 and 2011, 15 newborns and infants were diagnosed with DS mosaic. 9 of them presented with TL and 8 children suffered from ML-DS; 2 of them with a history of TL. In children without stigmata the special morphology and immunophenotype of blasts triggered the screening for GATA1 mutation and trisomy 21 mosaic.All newborns with TL achieved complete remission (CR). Due to clinical symptoms caused by the leukemic blasts, in 3 children low-dose cytarabine was applied. 1 patient died due to cardiac defect. In all patients GATA 1 s was confirmed. 6 children with ML-DS were initially treated according the AML-BFM protocol. After ML-DS was confirmed, therapy was continued with the intensity reduced schedule according to the ML-DS 2006 protocol. All children are still in CR (follow-up 1.8-7 years, median 2.7 yrs). 2 children with unknown trisomy 21 mosaic were diagnosed as acute megakaryoblastic leukemia (AMKL) and treated according the high risk arm of the AML-BFM 2004 including allogeneic stem cell transplantation in one child). GATA1 mutation was identified retrospectively. Both children are alive in CR.GATA1s associated leukemia has to be excluded in all young children with AMKL (

BACKGROUND Although the iron is an essential element for the physiological functions of cells, tissues and organs, it is also an important inductor of reactive oxygen species (ROS). MATERIAL AND METHODS Three groups of human spleen with autoimmune thrombocytopenia (AITP), hereditary spherocytosis (HS) and reference samples stained by haematoxylin and eosin, Perls' reaction for nonheme Fe(III) iron and Alcian blue for glycoconjugates detection were studied. RESULTS Positive Perls' reaction in both AITP and HS groups was seen. Higher positivity in the HS than in AITP group was observed. HS group showed a higher amount of acidic glycoconjugates deposits than AITP group. Iron overload in HS and AITP leads to overproduction of ROS. CONCLUSION We suggest that acidic glycoconjugates deposits are involved in antioxidant defence by elimination and restriction of iron as a ROS inducer (Fig. 4, Ref. 19).

Childhood leukemia arises from hematopoietic stem cells by induction of mutations. Quite often chromosomal translocations arise prenatally as first key event in multistage process of leukemogenesis. These translocations result in so called preleukemic gene fusions (PGFs), such as BCR-ABL and TEL-AML1, which generate hybrid proteins with altered properties. Critical DNA damage resulting in translocations are DNA double-strand breaks (DSBs). BCR-ABL and TEL-AML1 were shown to be associated with increased constitutive DSBs in various model systems. We analyzed cells from peripheral blood and CD34-/CD34+ cells from bone marrow of pediatric acute lymphoblastic leukemia (ALL) patients harboring BCR-ABL or TEL-AML1. We used sensitive technique that is based on automated enumeration of DSB co-localizing proteins γH2AX and 53BP1, which form so called DNA repair foci. We found that level of constitutive γH2AX/53BP1 foci is significantly higher in cells of ALL pediatric patients than in healthy subjects. There was also significant increased level of constitutive γH2AX/53BP1 foci in cells from ALL patients harboring BCR-ABL or TEL-AML1 compared to patients without PGFs. The same increase was observed regardless cell type for both PGFs. Our data on increased DSB levels in the BCR-ABL/TEL-AML1 patient's cells support a model where BCR-ABL/TEL-AML1 induces DNA instability through facilitating mutagenesis and appearance of additional genetic alterations driving leukemogenesis.

Acute leukemia (AL) of ambiguous lineage (AMBI-L) comprises up to 5% of AL cases in both children and adults. Although several definitions exist, a general treatment guideline has been missing. Single country studies usually report fewer than 50 cases of children or adults. Accordingly, the international iBFM AMBI2012 Study/Registry collected 275 AMBI-L cases in patients In total, 275 patients were included in the study. Of these, 240 fulfilled the definitions of biphenotypic/mixed phenotype AL, partially overlapping with cases in whom two clones had been identified (n=68) and 15 cases presented with undifferentiated AL. Most patients started their treatment with an ALL-type protocol (n=161), 79 with AML therapy, 27 with a combined regimen, including the Interfant protocols, 2 patients were not treated, 2 received other treatment, and in 4 patients such information was missing. The 5yEFS of the entire cohort was 56±3.7% and 5y overall survival was 67±3.3%. Patients treated by ALL-type protocols had superior 5 year event free survival (5yEFS) (70±4.6%, n=158) compared to those who started AML-type treatment (5yEFS: 40±6.4%, n=78) or hybrid ALL/AML treatment (5yEFS: 50±11%, n=27). Although protocol selection was likely biased, we recommend ALL treatment, when diagnostic findings, including molecular genetics, fail to indicate AML therapy. Although myeloperoxidase (MPO) has been used as the ultimate marker of myeloid lineage, patients who started with ALL-type treatment demonstrated a better prognosis even among cases classified as MPOpos/part pos (Fig. 1). These differences by initial choice of treatment are most prominent when CD19pos/part pos cases are analyzed regardless of the overall lineage (Fig. 2). This shows that at least for CD19pos/part pos cases in the absence of RUNX1/RUNX1T1 fusion, treatment should not start with current AML-type protocols. Until week 12, patients with higher leukemia burden were slightly overrepresented compared to non-AMBI ALL patients (data not shown). In addition, patients with higher residual disease had a much poorer prognosis. Thus, Prednisone poor and good responders (based on day 8 blood blast counts) had a 5yEFS of 50±9.7%, n=38 and 81±5.8%, n=82, respectively (p=0.005). By day 15 bone marrow (BM), only cutoffs of 10-4 and 10-3 were analyzed and neither showed significant associations with EFS. At the end of induction, patients with BM residual disease ≥10-3 had a 5yEFS of 51±10%, n=49 compared to 90±4.3% for those with lower levels, n=75 (p=0.0002). Especially higher residual disease at week 12 was associated with an extremely poor EFS (Fig. 3). Early identification of patients with inadequate response and designing alternative treatment for them is our important challenge. No overall benefit of transplantation was seen in patients who started on ALL treatment or hybrid ALL/AML treatment. Again, this may be caused by a biased selection of more severe cases for transplant. In patients who started with AML treatment, transplant appeared to improve prognosis (Fig. 4). This study provides the basis for improved treatment of future patients with AMBI-L, with more accurate diagnostics. OH, AL, IJ, EM and JS were supported by Czech Health Research Council 15-28525A. Disclosures Bleckmann: JazzPharma: Other: financial support of travel costs. Moricke:JazzPharma: Honoraria, Other: financial support of travel costs. Inaba:Arog: Research Funding. Kattamis:Novartis: Honoraria, Research Funding; ApoPharma: Honoraria. Reinhardt:Boehringer Ingelheim: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; Jazz Pharma: Other: Travel Accomodation; Celgene: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees.

Acute myeloid leukemia (AML) is characterized by the malignant transformation of myeloid cells from myeloblasts to a pathological cell clone. These pathological cell clones lose their ability to differentiate and mature, are no longer subject to regulatory mechanisms and suppress other components of normal hemopoiesis. AML does not fall under a single nosological entity. The heterogeneity of AML is reflected by differences in morphology and immunophenotype, as well as cytogenetic and molecular genetic abnormalities. It includes a number of subtypes, which can be further classified according to the FAB and World Health Organization (WHO) criteria.

Anaplastic large cell lymphoma represents approximately 10-15 % of pediatric non-Hodgkin lymphomas. Leukemic presentation is very rare, and in particular, the null phenotype ALCL without typical anaplastic morphology together with aberrant expression of CD13 and/or CD11b represents a diagnostic challenge. We report a case of a 9 year-old boy with leukemic presentation of ALCL with the typical translocation t(2;5)(p23;q35); in this patient, the only positive antigens identified by immunophenotyping were CD13, NG2 HLA-DR, and CD38. To our knowledge, aberrant expression of NG2 has never been reported in ALCL cases (Tab. 1, Fig. 6, Ref. 20).

Up to 5% of patients with acute leukemia (AL) are diagnosed as AL of ambiguous lineage. The ambiguous lineage ALs consist of mixed phenotype AL (MPAL, or biphenotypic AL, BAL), bilineal AL, switching AL and rare, undifferentiated ALs. From a molecular genetic point of view, they overlap with several molecular genetic subsets such as AL with MLL rearrangements or early T precursor AL. As no general treatment strategy exists, these patients have been variably treated with lymphoblastic (ALL)- , myeloid (AML)- or combined (hybrid) therapy, with or without stem cell transplant. They are often unreported as they are excluded from standard protocols. So far, attempts to shed more light on these patients has largely focused on definitions of ambiguous lineage AL. Only limited therapeutic observations have been possible in studies on this AL subset, usually reporting 50 or fewer pediatric/adult patients. In order to facilitate more detailed analyses, we have created an international study "iBFM AMBI2012 Study/Registry". In this study, patients under 18 years at diagnosis are eligible. Each center/country was asked to report all consecutive patients with ambiguous lineage AL, from a 2- to 13-year period ending May 31, 2015. The definitions included those with WHO and EGIL criteria and remained unchanged throughout the study. Complete information on type of treatment, follow up and immunophenotype was requested. Where available (n=101 at the time of this abstract uploading), raw cytometric FCS data files were stored centrally for review. Apart from the study itself, the central database served also as a basis for consulting individual patients during the diagnostic workup. Furthermore, data on fusion genes, cytogenetics, treatment response and availability of specimens for collateral studies were also collected. In total, 247 patients from Australia, Austria, Brazil, Czechia, Germany, Greece, Israel, Netherlands, NOPHO (Denmark, Estonia, Finland, Norway, Sweden, Iceland and Lithuania), PINDA (Chile), Poland, SAHOP (Argentina), Slovakia, St. Jude Children's Research Hospital (USA), Ukraine and United Kingdom are reported. Among those, 222 fulfilled the definitions of MPAL/BAL, partially overlapping with cases in whom two clones had been identified (n=47) and 14 cases presented with undifferentiated AL. Most of them, consistent with our general treatment guideline (Figure 1), started their treatment with an ALL type of protocol (n=150), 60 patients started on AML therapy, 8 patients received a combined regimen including the Interfant protocols, 2 patients were not treated, 13 received other treatment, and this information is missing in 9 patients (additional 5 pts. started on ALL treatment but their follow up information is incomplete). The 5 year event free survival of the entire cohort was 55±4% and its separation by first type of treatment is shown in Figure 2. In a collateral study, we set up a qPCR array on 90 genes that are characteristic of the lymphoid or myeloid lineages and/or are thought to be involved in their regulation. Using this array, sorted cells of granulocytic, monocytic, T, and B lineages at various stages of development (17 stages total) were analyzed and compared to samples of AL including 6 samples of MPAL of precursor B/myeloid phenotype. Although this array did not show a general deregulation in the MPAL genome compared to that in AL or healthy cells, subtle changes were seen such as decrease of CEBPE and LILRA2 gene expression, in comparison to classical B precursor ALL. Overall, our data shows that the general treatment guideline (Figure 1), which favors ALL treatment is justified by the outcome. However, although this study is larger than those published, caution is needed during its interpretation due to variations in diagnostics and treatment among the participating countries. Therefore, our data should be viewed as a basis for non-ambiguous treatment guidelines that will direct each patient to either ALL or AML treatment. These guidelines will be tested prospectively. In addition, the framework of this study is being used as a basis of consulting new AL cases with diagnostic uncertainties. Furthermore, it serves as a data resource for biologic studies. Supported by AZV 15-28525A, UNCE 204012, NT/14534-3, NT/13462-4, P302/12/G101. Disclosures Kattamis: Novartis: Research Funding, Speakers Bureau; ApoPharma: Speakers Bureau.

Acute lymphoblastic leukemia is the most common form of cancer in children. The 10-year event-free survival ranged from 77 to 85% after having achieved complete remission rates of 93% or higher. The main cause of treatment failure is relapse arising from outgrowth of residual leukemic cells that are refractory to therapy. An intense effort has been made to develop methods to determine the degree of minimal residual leukemia cells present in patients considered to be in morphological remission. Because of the strong correlation between minimal residual disease (MRD) levels and risk of relapse, monitoring of MRD provides unique information regarding treatment response. The MRD monitoring based on real-time quantitative PCR detection of patient-specific immunoglobulin and T-cell receptor (Ig/TCR) gene rearrangements is currently considered to be the most reliable tool for MRD-based diagnosis in ALL. Because the significance of MRD monitoring has been strongly supported by several studies and because it has been implemented in the latest protocols, there has been a significant effort to develop MRD monitoring in the Slovak Republic since 2005. Between October 2006 and December 2009, 50 children with ALL who were treated at three Slovak centers were included in the RQ PCR MRD pilot project. A total of 40 patients with BCP-ALL ( B cell precursor ALL) and 4 patients with T ALL were analyzed for Ig/TCR rearrangement. We identified 106 different rearrangements in the 44 ALL patients analyzed. Based on MRD stratification, we identified 26 patients who were stratified into the HRG ( high risk group) (n = 3; 11.5%), IRG ( intermediate risk group) (n = 14; 54%) and SRG ) standard risk group) (n = 9; 34.5%). Morphology-based risk stratification allows the identification of most HRG patients identified also by MRD-based stratification, but fails to discriminate the IRG assigned to therapy reduction. Patients in the SRG and the IRG could profit from MRD-based risk assignment

There is a fear that antibacterial prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX) in children with acquired immunodeficiency syndrome (AIDS)1 might lead to increase of antimicrobial resistance in bacteria. We compared culture results and resistance pro- files in children receiving TMP-SMX prophylaxis 3 times weekly orally in Phnom Penh Cambodia and in Nairobi Kenya after 12–18 months of highly active antiretroviral therapy (HAART) therapy. Thirty-three children from Phnom Penh (group A) and 42 patients from Nairobi (group B) were compared. CD4 count varied from 10 to 220 at admission. Oropharyngeal swab cultures were transported to the reference laboratory of antimicrobial resistance of the Slovak Ministry of Health. Tables 1 and 2 show comparison of culture results and resistance patterns in human immunodeficiency virus-positive children in Phnom Penh and Nairobi at the initiation of HAART and after 12–18 months of therapy. (excerpt)

Abstract 888 Introduction: Pediatric acute megakaryoblastic leukemia (AMKL) occurred in 6.6% (84/1271) of the children enrolled to the AML-BFM98 and 2004 studies. Despite a similar phenotype in morphology and immunophenotype, AMKL shows a heterogenous cytogenetic distribution (normal karyotype 23%, complex karyotype 21%, t(1;22) 9%; MLL-rearrangement 8%; monosomy 7 5%, trisomy 8 5%; other aberrations 29%). Mutations of the hematopoietic transcription factor GATA1 have been identified in almost all children suffering myeloid leukemia of Down syndrome (ML-DS). In addition, GATA1 mutations (GATA1mut) could be identified in children with trisomy 21 mosaic. Here, AMKL without evidence of Down syndrome or Down syndrome mosaic were analyzed for mutations in exon 1, 2 or 3 of the transcription factor GATA1. Patients: Seventy-one children from the AML-BFM Study group (n=51; 2000–2011), the Netherlands (n=10), France (n=3) and Scandinavia (n=7) were included. Within the AML-BFM Group the 51 analyzed patients showed similar characteristics compared to the total cohort of 84 children with AMKL of the AML-BFM 98 and 2004 studies. AMKL was confirmed according to the WHO classification by genetics (t(1;22)); morphology and immunophenotyping. Table 1a) summarizes the patientxs characteristics and b) the cytogenetic results. Methods: For GATA1 mutation screening genomic DNA was amplified by PCR reaction for exon 1, 2, and 3. PCR amplicons were analyzed by direct sequencing or following denaturing high-performance liquid chromatography (WAVE). Results: Seven different GATA1 mutations were detected in 8 children (11.1%; table 2). In all GATA1mut leukemia, a trisomy 21 within the leukemic blasts could be detected. Seven out of these 8 children and all other 64 AMKL patients have been treated with intensive chemotherapy regimens according the study group protocols. The results are given in table 2. All achieved continuous complete remission (CCR; 0.4 to 4.2 years). In one newborn with typical morphology and immunophenotype a GATA1mut associated transient leukemia was supposed. The child achieved CCR (follow-up 6 years). In total, allogeneic stem cell transplantation in 1st CR was performed in 6 children with AMKL (GATA1mut leukemia n=1). Conclusions: GATA1 mutations occurred in 11% of children with AMKL without any symptoms or evidence of trisomy 21 or trisomy 21 mosaic. GATA1 mutations are associated with a trisomy 21 within the leukemic blasts. Although non-response occurred, prognosis was significant better compared to other AMKL. Therefore, analysis of GATA1 mutation in infant AMKL is strongly recommended. Whether treatment reduction similar to ML-DS Down syndrome is feasible needs to be confirmed. Disclosures: No relevant conflicts of interest to declare.

Abstract 2539 Introduction: Transient leukemia (TL) occurs in 5 to 10% of newborns with Down syndrome (DS). In almost all cases it resolves spontaneously within 3 months, but 20–25% of the children develop myeloid leukemia (ML-DS) until the age of 4 years. TL and ML-DS can occur also in children without any clinical signs of Down syndrome, but with constitutional trisomy 21 due to mosaicism. It can be difficult to diagnose TL or ML-DS in these children and the treatment strategies have not been defined. Patients/Material: Between 1/2002 and 7/2011, 15 newborns and infants were diagnosed with DS mosaic. Nine of them presented with TL and 8 children suffered from ML-DS; 2 of them with a history of TL (table 1). In children without any stigmata the special morphology and immunophenotype of blasts triggered the screening for GATA1 mutation and trisomy 21 mosaic. Diagnostic work-up was performed according to standard guidelines: morphology, immunophenotyping (IP), cytogenetics and FISH (trisomy 21), molecular genetics (GATA 1 mutation screening). Screening of GATA1 mutations was done with direct sequencing of PCR product (Exon1, Exon2, and Exon3). For monitoring of GATA1 mutant clone qPCR have been used with patient specific TaqMan probes and primers. Mosaic was detected by cytogenetics or FISH in bone marrow, blood and/or fibroblasts. Results: All newborns with TL achieved complete remission (CR). Due to clinical symptoms caused by the leukemic blasts, in 3 children low-dose cytarabine was applied. One patient died due to cardiovascular failure. In all patients GATA 1 mutation was confirmed. Minimal residual disease by qPCR (mutation-specific probes) or immunophenotyping (IP) revealed negativity in 3 out of 3 children monitored (follow-up 2 to 10.1 yrs). Two children with (unknown) trisomy 21 mosaic were diagnosed as acute megakaryoblastic leukemia (AMKL) and treated according the high risk arm of the AML-BFM 2004 including allogeneic stem cell transplantation (one child), GATA1 mutation was identified retrospectively. Both children are alive in CR. Six children with ML-DS were initially treated according the AML-BFM protocol. After ML-DS was confirmed, therapy was continued with the intensity reduced schedule according to the ML-DS 2006 protocol. All children are still in CR (follow-up 1.5 to 6.7 years, median 2.4 yrs). This was confirmed by MRD-monitoring, which achieved negativity after two treatment elements (qPCR Conclusions: GATA1 mutated leukemia has to be excluded in all young children with AMKL ( Disclosures: No relevant conflicts of interest to declare.

Abstract 481 Childhood leukemia frequently originates prenatally. Only a small percentage ( The high incidence (5 to 10%) of the transient leukemia (TL) in newborns with trisomy 21 and the high risk to develop a myeloid leukemia of Down Syndrome (ML-DS) within the first 4 years of life supported the hypothesis that the elimination of the preleukemic GATA1 positive clone might prevent leukemia. Prerequisites are the high sensitivity of TL-blasts to cytarabine, the recurrence of the same GATA1-mutated clone and the feasibility to monitor the preleukemic clone. Since 4/2007 69 children with TL were enrolled the study “Prevention of Myeloid Leukemia in Children with Down Syndrome and Transient Leukemia” (EudraCT 2006-002962-20) ; Germany n=50, The Netherlands n=16, Slovakia n=1, Czech Republic n=2). Inclusion criteria were met by 52 children (study patients), 17 children were observed only (protocol patients). Table 1 summarizes the patients' characteristics. The TL and ML-DS specific mutations of the transcriptions factor GATA1 have been detected in 60 children (87%), failure of detection were caused by low percentage of blasts ( Totally, 58 % of the children showed clinical symptoms associated to the TL, severe complications have been reported in 22 children (table 2). According to the study guidelines 20 out of these 22 children were treated with low dose cytarabine (1.5mg/kg body weight 1 week). Enrollment to the study including reference diagnostics and consulting, and a consequent treatment seems to improve the prognosis of this particular group. Compared to the historical group of children with similar characteristics (Klusmann et al. Blood 111(6):2991-8, 2008), the overall survival (2 years) significantly increased from 55±7% to 84±8%, p=0.03. MRD diagnostics by qRT-PCR and/or immunophenotyping was performed in 53 children (77%). Reasons for failure were early deaths (n=9; cardiac defects n=1, prematurity/MOV n=7, liver fibrosis n=1), refusal of monitoring by the parents (n=3), lack of material (n=4). If the MRD-level at week 8 and/or 10 exceeded 10-3 (qRT-PCR) or 10-2 (immunophenotyping), respectively, intervention with low-cytarabine was recommended. Currently, 39 children were already analyzed at week 12 (1st endpoint). In 7 children (13%) treatment recommendation according to high MRD levels were given. With exception of transient myelosuppression (CTC Grade II) no severe side effects occurred. All children but two became MRD negative at week 12. To date one child with persistent detectable MRD levels suffered ML-DS (1 year after TL). In summary, participating in the study and treatment of children with TL causing severe clinical symptoms seems to improve the prognosis. Although the recruitment into the study is faster than expected and the results to date are promising, the follow-up is much too short to draw definitive conclusion. Disclosures: No relevant conflicts of interest to declare.