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Juvenile myelomonocytic leukemia (JMML) is a rare clonal stem cell disorder that occurs in early childhood and is characterized by the hyperactivation of the RAS pathway in 95% of the patients. JMML is characterized by a hyperproliferation of granulocytes and monocytes, and little is known about the heterogeneous nature of leukemia-initiating cells, as well as of the cellular hierarchy of the JMML bone marrow. In this study, we report the generation and characterization of a novel patient-derived three-dimensional (3D) in vitro JMML model, called patient-derived JMML Atypical Organoid (pd-JAO), sustaining the long-term proliferation of JMML cells with stem cell features and patient-specific hallmarks. JMML cells brewed in a 3D model under different microenvironmental conditions acquired proliferative and survival advantages when placed under low oxygen tension. Transcriptomic and microscopic analyses revealed the activation of specific metabolic energy pathways and the inactivation of processes leading to cell death. Furthermore, we demonstrated the pd-JAO–derived cells’ migratory, propagation, and self-renewal capacities. Our study contributes to the development of a robust JMML 3D in vitro model for studying and defining the impact of microenvironmental stimuli on JMML disease and the molecular mechanisms that regulate JMML initiating and propagating cells. Pd-JAO may become a promising model for compound tests focusing on new therapeutic interventions aimed at eradicating JMML progenitors and controlling JMML disease.

Background Functional variants of the cytotoxic T-lymphocyte antigen-4 (CTLA4) could contribute to the pathogenesis of disorders characterized by abnormal T-cell responses. Case presentation We report a case of a 13-year-old girl who first presented with polyarticular juvenile idiopathic arthritis poorly responsive to treatment. During the following years the patient developed cytopenias, chronic lymphoproliferation, high values of T-cell receptor αβ+ CD4- CD8- double-negative T cells and defective Fas-mediated T cells apoptosis. Autoimmune lymphoproliferative syndrome was diagnosed and therapy with mycophenolate mofetil was started, with good hematological control. Due to the persistence of active polyarthritis, mycophenolate mofetil was replaced with sirolimus. In the following months the patient developed hypogammaglobulinemia and started having severe diarrhea. Histologically, duodenitis and chronic gastritis were present. Using the next generation sequencing-based gene panel screening, a CTLA4 mutation was detected (p.Cys58Serfs*13). At the age of 21 the patient developed acute autoimmune hemolytic anemia; steroid treatment in combination with abatacept were started with clinical remission of all symptoms, even arthritis. Conclusions Targeted immunologic screening and appropriate genetic tests could help in the diagnosis of a specific genetically mediated immune dysregulation syndrome, allowing to select those patients who can take advantage of target therapy, as in the case of abatacept in CTLA4 deficiency.

In recent years, monogenic causes of immune dysregulation syndromes, with variable phenotypes, have been documented. Mutations in the lipopolysaccharide-responsive beige-like anchor (LRBA) protein are associated with common variable immunodeficiency, autoimmunity, chronic enteropathy, and immune dysregulation disorders. The LRBA protein prevents degradation of cytotoxic T-lymphocyte antigen 4 (CTLA4) protein, thus inhibiting immune responses. Both LRBA and CTLA4 deficiencies usually present with immune dysregulation, mostly characterized by autoimmunity and lymphoproliferation. In this report, we describe a patient with an atypical clinical onset of LRBA deficiency and the patient's response to abatacept, a fusion protein-drug that mimics the action of CTLA4.

Objective of the Study:In this study we aimed to retrospectively evaluate how centers, belonging to the Associazione Italiana Ematologia e Oncologia Pediatrica (AIEOP), manage severe acquired hypofibrinogenemia in children with acute lymphoblastic leukemia, particularly evaluating the therapeutic role of human fibrinogen concentrate (HFC) and fresh frozen plasma (FFP).Methods:We conducted a survey among AIEOP centers; thereafter, we collected and analyzed data with regard to the treatment of episodes of severe acquired hypofibrinogenemia occurring during the induction and reinduction phases of the AIEOP-BFM ALL 2009 protocol.Results:In total, 15 of the 37 AIEOP centers invited to join the survey agreed to collect the data, with 10 and 5 centers declaring to react to severe acquired hypofibrinogenemia (

10001 Background: Approximately 15-20% of pediatric pts with ALL or LL will be refractory to/relapse after frontline treatment; relapsed disease is associated with poor outcomes. In a phase 2 study, 2 of 7 (28.6%) pts with T-cell ALL in first relapse achieved a complete response (CR) using the vincristine, prednisone, PEG-asparaginase, and doxorubicin (VPLD) reinduction backbone. DARA, a human IgGκ monoclonal antibody targeting CD38 approved for treating multiple myeloma, has shown preclinical efficacy in ALL models. We report the initial results of DARA plus VPLD in pediatric and young adult pts with relapsed/refractory T-cell ALL or LL enrolled in the phase 2, open-label DELPHINUS study. Methods: Eligible pts were aged 1-30 y, had T-cell ALL or LL in first relapse or refractory to 1 prior induction/consolidation regimen, and had a performance status ≥70. DARA (16 mg/kg IV QW) was given with VPLD in Cycle 1 and with methotrexate, cyclophosphamide, cytarabine, and 6-mercaptopurine in Cycle 2. Pts received age/risk-adjusted intrathecal therapy. Response was measured at the end of each cycle by local bone marrow morphology. The primary endpoint for ALL pts was CR rate in pediatric pts at the end of Cycle 1. Pts achieving CR after Cycles 1 or 2 could proceed to allogeneic HSCT off study. Overall response rate (ORR) was defined as CR or CR with incomplete hematological recovery (CRi) at any time before start of subsequent therapy or HSCT. Minimal residual disease (MRD) negativity (< 0.01%) at any time before disease progression, start of subsequent therapy, or HSCT was centrally reviewed by flow cytometry. Results: Twenty-four pediatric (age 1-17 y) and 5 young adult (age 18-30 y) ALL pts and 10 LL pts (age 1-30 y) received ≥1 DARA dose. Median (range) age was 10.0 (2-25) y (ALL) and 14.5 (5-22) y (LL); median (range) time from initial diagnosis to first study treatment was 2.0 (0.1-6.1) y (ALL) and 0.8 (0.5-6.0) y (LL). Pediatric ALL pts received a median (range) of 2 (1-3) treatment cycles; young adult ALL pts and LL pts each received 2 (1-2). Among pediatric ALL pts, 10 (41.7%) pts (90% CI, 24.6-60.3) achieved CR at the end of Cycle 1. ORR was 83.3% (CR, 13 [54.2%] pts; CRi, 7 [29.2%] pts) in pediatric and 60.0% (all CR) in young adult ALL pts and 40.0% (all CR) in LL pts. Ten (41.7%) pediatric ALL pts achieved MRD negativity. All pediatric ALL pts had a grade 3/4 TEAE. No pediatric ALL pt discontinued DARA primarily due to AEs and 1 (4.2%) died due to TEAEs (brain edema and hepatic failure) attributed to study treatment but unrelated to DARA. Conclusions: The addition of DARA to VPLD in pediatric and young adult pts with relapsed/refractory T-cell ALL or LL showed initial activity, generating improved response rates compared to those achieved with backbone therapy alone, with a manageable safety profile. Clinical trial information: NCT03384654.

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative therapy for most children with juvenile myelomonocytic leukemia (JMML). Novel therapies controlling the disorder prior to HSCT are needed. We conducted a phase 2, multicenter, open-label study to evaluate the safety and antileukemic activity of azacitidine monotherapy prior to HSCT in newly diagnosed JMML patients. Eighteen patients enrolled from September 2015 to November 2017 were treated with azacitidine (75 mg/m2) administered IV once daily on days 1 to 7 of a 28-day cycle. The primary end point was the number of patients with clinical complete remission (cCR) or clinical partial remission (cPR) after 3 cycles of therapy. Pharmacokinetics, genome-wide DNA-methylation levels, and variant allele frequencies of leukemia-specific index mutations were also analyzed. Sixteen patients completed 3 cycles and 5 patients completed 6 cycles. After 3 cycles, 11 patients (61%) were in cPR and 7 (39%) had progressive disease. Six of 16 patients (38%) who needed platelet transfusions were transfusion-free after 3 cycles. All 7 patients with intermediate- or low-methylation signatures in genome-wide DNA-methylation studies achieved cPR. Seventeen patients received HSCT; 14 (82%) were leukemia-free at a median follow-up of 23.8 months (range, 7.0-39.3 months) after HSCT. Azacitidine was well tolerated and plasma concentration-–time profiles were similar to observed profiles in adults. In conclusion, azacitidine monotherapy is a suitable option for children with newly diagnosed JMML. Although long-term safety and efficacy remain to be fully elucidated in this population, these data demonstrate that azacitidine provides valuable clinical benefit to JMML patients prior to HSCT. This trial was registered at www.clinicaltrials.gov as #NCT02447666.

Acute promyelocytic leukaemia (APL) is a rare subtype ofchildhood acute myeloid leukaemia (AML), accounting for5–12% of all AML cases. Treatment with all-trans-retinoicacid (ATRA) and anthracyclines yields complete remission(CR) rates >90% and 10-year event-free survival (EFS) ratesaround 80%.1–3The recent front-line arsenic trioxide(ATO)-based regimens have further improved the APL out-come by reducing toxicity and preventing relapse.4–6Relapsed APL patients are a rare and heterogeneous group,whose prognosis depends on front-line treatment and timeelapsing between diagnosis and recurrence. Currently, ATOis the treatment of choice for relapsed APL. Due to the rarityof relapsed childhood APL, 17–27% in ATRA- andchemotherapy-1,3,7–9and 4% in ATO-containing regimens,10it will be difficult, in the future, to design future prospectivecomparative trials for these patients. In an attempt to designtherapeutic guidelines, recommendations on management ofrelapsed/refractory paediatric APL have been publishedrecently

The aim of this study was to investigate the association of neuroimaging, clinical, and laboratory findings in children with different underlying diseases who developed posterior reversible encephalopathy syndrome (PRES). All consecutive pediatric patients referred to our institute between 2000 and 2017 were retrospectively evaluated for newly diagnosed PRES. Clinical data, medical history, and therapies administered at the time of PRES and laboratory findings were reviewed as the magnetic resonance imaging (MRI) obtained at PRES presentation and during follow-up. Statistics included Mann–Whitney U, Chi-square, and Fisher's exact tests. A total of 39 pediatric patients (25 males, median age = 8.8 years) with a confirmed diagnosis of PRES were included. The patients were divided into four groups based on the underlying disease: (1) patients with hemato-oncological diseases not transplanted (n = 15, 38.5%), (2) who underwent hematopoietic stem cell transplantation (HSCT; n = 12, 30.8%), (3) affected by renal (n = 8, 20.5%), and (4) by autoimmune diseases (n = 4, 10.2%). Hemato-oncological patients and those undergoing HSCT presented a higher incidence of involvement of deep gray matter structures and hemorrhagic lesions when compared with patients with renal and autoimmune disorders (p = 0.036 and p = 0.036, respectively). No differences emerged among different groups of patients regarding presenting PRES symptoms, arterial blood pressure, laboratory findings, and extent of MRI abnormalities and these parameters did not show association with outcome.In conclusion, in pediatric patients with different diseases who develop PRES, involvement of deep gray matter structures and hemorrhagic lesions are more common in hemato-oncological patients and those undergoing HSCT. Clinical and radiologic outcome is favorable independently of clinical data and extent of MRI abnormalities.

Importance: Blinatumomab is a CD3/CD19-directed bispecific T-cell engager molecule with efficacy in children with relapsed or refractory B-cell acute lymphoblastic leukemia (B-ALL). Objective: To evaluate event-free survival in children with high-risk first-relapse B-ALL after a third consolidation course with blinatumomab vs consolidation chemotherapy before allogeneic hematopoietic stem cell transplant. Design, Setting, and Participants: In this randomized phase 3 clinical trial, patients were enrolled November 2015 to July 2019 (data cutoff, July 17, 2019). Investigators at 47 centers in 13 countries enrolled children older than 28 days and younger than 18 years with high-risk first-relapse B-ALL in morphologic complete remission (M1 marrow

Objective To describe the clinical characteristics, treatment, and outcomes of a multinational cohort of patients with macrophage activation syndrome (MAS) and thrombotic microangiopathy (TMA). Study design International pediatric rheumatologists were asked to collect retrospectively the data of patients with the co-occurrence of MAS and TMA. Clinical and laboratory features of patients with systemic juvenile idiopathic arthritis (sJIA)-associated MAS and TMA were compared with those of an historical cohort of patients with sJIA and MAS. Results Twenty-three patients with MAS and TMA were enrolled: 17 had sJIA, 2 systemic lupus erythematosus, 1 juvenile dermatomyositis, 1 mixed connective tissue disease, and 2 undifferentiated connective tissue disease. Compared with the historical cohort of MAS, patients with sJIA with coexistent MAS and TMA had higher frequencies of renal failure and neurologic involvement, hemorrhage, jaundice, and respiratory symptoms, as well as more severe anemia and thrombocytopenia, higher levels of alanine aminotransferase, lactate dehydrogenase, bilirubin and D-dimer, and lower levels of albumin and fibrinogen. They also required admission to the intensive care unit more frequently. Among patients tested, complement abnormalities and reduced ADAMTS13 activity were observed in 64.3% and 44.4% of cases, respectively. All patients received glucocorticoids. Treatment for TMA included plasma-exchange, eculizumab, and rituximab. Conclusions The possible coexistence of MAS and TMA in rheumatic diseases may be underrecognized. This association should be considered in patients with MAS who develop disproportionate anemia, thrombocytopenia, and lactate dehydrogenase increase, or have multiorgan failure.

PSTPIP1-associated myeloid-related proteinemia inflammatory (PAMI) syndrome is a rare early-onset autoinflammatory disease associated with various hematologic findings, including chronic neutropenia and pancytopenia. We report a unique case of PAMI syndrome in a toddler with transfusion-dependent hemolytic anemia, hepatosplenomegaly, failure to thrive, developmental delay, and multiple malformations. Because of acute inflammatory-driven decompensation, anakinra was started with dramatic improvement of both the hematologic and neurologic involvement. A customized next-generation sequencing panel later identified a de novo pathogenic variant in the PSTPIP1 gene, confirming the diagnosis. Our case illustrates the broad spectrum of phenotypes associated with PAMI syndrome, which should be considered in any case of unexplained cytopenias associated with autoinflammatory stigmata. It is also one of the few reports of neurologic involvement in PSTPIP1-associated inflammatory diseases. Increased awareness of this rare disease and early performance of genetic testing can correctly diagnose PAMI syndrome and prevent disease complications.

Background Anti-N-methyl- d -aspartate receptor encephalitis is a central nervous system inflammatory autoimmune disease affecting adults and children. The use of first- and second-line immunotherapies is supported. Recent reports suggest the efficacy of bortezomib in severe anti-N-methyl- d -aspartate encephalitis in adult patients not responsive to second-line treatment; there are no data about pediatric patients. patient description We describe an eight-year-old child with anti-N-methyl- d -aspartate encephalitis not responsive to first- and second-line treatments who experienced marked clinical improvement after bortezomib administration. Discussion Bortezomib is a selective and reversible inhibitor of the 26S proteasome, which is used to treat oncologic and rare autoimmune disorders in pediatric patients. As observed in adult patients, bortezomib administration induced anti-N-methyl- d -aspartate antibody titer decline and clinical improvement with an acceptable risk profile. Conclusion This is the first report of the use of bortezomib in children with anti-N-methyl- d -aspartate encephalitis; it could be a useful therapeutic option in children with refractory anti-N-methyl- d -aspartate encephalitis.

Key Points Immunological dysregulation may underlie unusual autoimmune diseases, which also deserve to be investigated from a genetic point of view.

Background: To date, no data on the adherence to specific guidelines for children with chronic myeloid leukemia (CML) in chronic phase (CP) have been reported. Methods: Since 2001, guidelines for treatment with imatinib mesylate (IM) and monitoring in patients younger than 18 years with CP-CML have been shared with 9 pediatric referral centers (P centers) and 4 reference centers for adults and children/adolescents (AP centers) in Italy. In this study, the adherence to these guidelines was analyzed. Results: Thirty-four patients with a median age of 11.4 years and 23 patients with a median age of 11.0 years were managed at 9 P and at 4 AP centers, respectively. Evaluations of bone marrow (BM) and/or peripheral blood (PB) were available for more than 90% of evaluable patients. Cytogenetics and molecular monitoring of PB were more consistently performed in AP centers, whereas molecular analysis of BM was carried out more frequently in P centers. Before 2009, some patients who responded to IM underwent a transplantation, contrary to the guidelines’ recommendations. Conclusions: Our experience shows that having specific guidelines is an important tool for an optimal management of childhood CP-CML, together with exchange of knowledge and proactive discussions within the network.

Background: Children with high-risk 1st relapse B-ALL after frontline chemotherapy have a poor prognosis and are candidates for allogeneic hematopoietic stem cell transplant (alloHSCT) after achieving complete remission (CR). We previously reported that treatment with blinatumomab, a CD3/CD19-directed BiTE ® (bispecific T-cell engager) molecule, resulted in superior efficacy in event-free survival (EFS) and minimal residual disease (MRD) remission vs intensive multidrug chemotherapy as the 3rd consolidation block before alloHSCT in children with high-risk 1st relapse B-ALL in a phase 3 RCT (JAMA 2021;325:843-54).Here we provide FU of EFS, overall survival (OS), and safety as of Sep 2020, ie, beyond the July 2019 primary analysis. Methods: In this phase 3 RCT (Amgen NCT02393859), children >28 days and Results: Enrollment was terminated based on the interim analysis for benefit of blinatumomab (7/17/19 primary analysis). The following results reflect an updated analysis as of 9/14/20. Between Nov 2015-Aug 2019, 111 patients were randomized; 54 (49%) received blinatumomab and 57 (51%) received chemotherapy at 47 centers in 13 countries. Baseline characteristics were comparable in both arms (Table 1). After a median FU of 31 months, EFS was significantly superior with blinatumomab vs chemotherapy [63% vs 37%, stratified log-rank p CAR-T cell treatment after investigational therapy was reported for some patients; blinatumomab arm: 2/54 and chemotherapy arm: 9/57 patients (Table 2). Both blinatumomab arm patients had CD19+ disease after blinatumomab treatment, with OS of 22.1 and 12.8 months, and 1/2 alive at last FU. Of the 5 patients in the chemotherapy arm who later received blinatumomab, 3 had CD19+ disease after chemotherapy and 2 did not have CD19 expression data available; OS for these 5 patients ranged from 11.1-22.9 months with 2/5 alive at last FU. There were also 3 patients in the chemotherapy arm (but no exposure to blinatumomab) with CD19+ relapse who received CAR-T at relapse; OS for these patients ranged from 18.8-28.0 months and 2/3 were alive at last FU; a fourth patient with CD19-negative relapse who received chemotherapy only at relapse had OS of 24.8 months. Summary/Conclusion: In children with high-risk 1st relapse B-ALL, treatment with 1 cycle of blinatumomab vs chemotherapy before alloHSCT resulted in significantly superior EFS and improved OS. The incidence of CD19-negative relapse after blinatumomab was low. No evidence of a negative impact of blinatumomab followed by CAR-T cell therapy was noted in this small subset of patients. Figure 1 Figure 1. Disclosures Locatelli: Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Miltenyi: Speakers Bureau; Medac: Speakers Bureau; Jazz Pharamceutical: Speakers Bureau; Takeda: Speakers Bureau. Zugmaier: Amgen: Current Employment; Micromet/Amgen: Patents & Royalties: Patents 20190300609 and 20130323247 licensed; receives royalties of family members of international applications published as WO2010/052014; WO2010/052013; WO2011/051307; WO2012/055961; WO 2012/062596; WO2014/122251; and WO2015/181683; Amgen: Current equity holder in publicly-traded company. Rizzari: Sobi: Other: personal fees; Shire: Other: Grants and personal fees; Medac: Other: Grants and personal fees; Jazz Pharmaceuticals: Other: Personal fees; Amgen: Other: Personal fees. Morris: Amgen: Current Employment. Gruhn: AmgenGmbh: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel costs; Bellicum Pharma Gmbh: Membership on an entity's Board of Directors or advisory committees, Other: travel costs; EUSA Pharma Gmbh: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Honoraria, Other: travel costs; Novartis Pharma Inc.: Honoraria, Other: travel costs; pfizer: Honoraria; servier: Honoraria, Other: travel costs; Neovii Biotech GmbH: Other: travel costs; medac GmbH: Other: travel costs. Zeng: Amgen: Current Employment. Pilankar: Iqvia: Current Employment, Other: Iqvia provides support for Amgen. Kormany: Amgen: Current Employment. Moericke: Amgen: Other: Grants; Shire: Other: Personal fees. Peters: Amgen: Membership on an entity's Board of Directors or advisory committees, Other: Travel grants. Saha: Amgen: Other: Personal fees. von Stackelberg: Amgen: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Miltenyi: Consultancy, Honoraria.

Introduction: Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer, representing ~25% of cancer diagnoses in children. Approximately 20% of childhood leukemias are of myeloid origin with the majority being acute. Isatuximab (Isa) is a monoclonal antibody that binds to a specific epitope of CD38 and exerts anti-multiple myeloma (MM) effects through several modes of action. Isa is approved for use in MM in adults. CD38 expression is high in some acute leukemia subsets in pediatric patients, making CD38 a potential target for acute leukemia treatment in children. Methods: ISAKIDS (NCT03860844) is a Phase 2, single-arm, multicenter, open-label study evaluating the antitumor activity, safety, and pharmacokinetics (PK) of Isa in combination with standard salvage chemotherapies in children with relapsed or refractory (R/R) leukemia in first or second relapse; including both T-ALL and B-ALL and acute myeloid leukemia (AML), conducted in 3 separate cohorts. Children from 2 years (yrs) to Results: 24 pts were enrolled (10, B-ALL; 7, T-ALL; 7, AML) and treated. Baseline characteristics were comparable between cohorts; median age (range) B-ALL 6.5 (3-14) yrs; T-ALL 10.0 (7-16) yrs; AML 7.0 (2-17) yrs. Males (4/10 B-ALL; 6/7 T-ALL; 3/7 AML). Evaluable Lansky scores of 90 - 100 (9/10 B-ALL; 3/4 T-ALL; 4/6 AML). Mean (standard deviation) time from initial diagnosis to first dose of investigational medicinal product (IMP) was 2.6 (1.0) yrs, 1.2 (0.6) yrs, and 1.0 (0.3) yrs for the B-ALL, T-ALL, and AML groups, respectively. Number of prior regimens, median (range) was 6 (1-≥8), 3 (1-≥8), 4 (1-≥8) for the B-ALL, T-ALL, and AML groups, respectively, corresponding to inclusion of pts with very advanced disease. Three pts presented with hyperleukocytosis >20 x 10 9/L. Among 23 pts assessed for CD38 expression, all except 2 (1 B-ALL and 1 AML) were CD38 positive. There were 17 evaluable pts with valid response data collected up to the cutoff date (May 11, 2021). Of the evaluable participants, CR+CRi were observed for: 3/7 (42.9%) in the B-ALL cohort, 2/6 (33.3%) in the T-ALL cohort, and 2/4 (50.0%) in the AML cohort (Table). Safety data showed that Grade ≥3 TEAEs occurred in 17 pts (Table). Infusion reactions (majority Grade 1 or 2) occurred in 9/24 pts (2/10 B-ALL; 4/7 T-ALL; 3/7 AML). Three pts had Grade 5 TEAEs (deaths: 1 B-ALL and 2 AML). One subject in the AML cohort had cytokine-release syndrome (CRS) related to IMP with progressive disease as a confounding factor. The other 2 deaths were not treatment related. One subject in the AML cohort had cellulitis Grade 5 and 1 subject in the B-ALL cohort had septic shock Grade 5 as cause of death. Preliminary PK analysis on 18 pts (>2 yrs) showed that Isa PK parameters including exposure PK parameters in children with ALL or AML are consistent with those observed in adult ALL pts. PK modeling approaches predict a slightly lower exposure ( Conclusions: In a poor prognostic relapsed population, 7/17 (41.2%) pts achieved CR+CRi. Safety profile and exposure is consistent with the available data for adults. Enrollment will be opened for pts Figure 1 Figure 1. Disclosures Baruchel: Kite/Gilead: Other: Investigator; Novartis, Servier, Celgene, Jazz, Janssen, Sanofi, Amgen,Astra-Zeneca: Membership on an entity's Board of Directors or advisory committees, Other: Satellite symposium; Shire Servier: Research Funding. Abrahamsson: wedish Children´s Cancer Foundation. Research grants and 50% senior research position for clinical research on pediatric leukemia: Research Funding. Nysom: Bayer, Y-mAbs, EUSA Pharma: Consultancy, Honoraria. Rizzari: Sobi: Other: personal fees; Jazz Pharmaceuticals: Other: Personal fees; Amgen: Other: Personal fees; Medac: Other: Grants and personal fees; Shire: Other: Grants and personal fees. Cesaro: Sobi: Membership on an entity's Board of Directors or advisory committees; Gilead: Speakers Bureau. Duarte: Amgen: Consultancy, Other: Advisory Board; Novartis: Consultancy; Jazz Pharma: Research Funding. Kang: Amgen Korea: Membership on an entity's Board of Directors or advisory committees, Research Funding; Cartexell: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis Korea: Membership on an entity's Board of Directors or advisory committees, Research Funding. Kattamis: Agios Pharmaceuticals: Consultancy; IONIS: Consultancy; VIFOR: Consultancy; CRISPR/Vertex: Consultancy, Honoraria; BMS/Celgene: Consultancy, Honoraria, Research Funding; Chiesi: Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Amgen: Consultancy. Tøndel: Sanofi: Research Funding. Ivanina: Sanofi: Current Employment. Brillac: Sanofi: Current Employment. Wang: Sanofi: Current Employment. Oprea: Sanofi: Current Employment, Other: may have stock options . Abbadessa: Sanofi: Current Employment. Zwaan: Sanofi: Consultancy.

Background. Hypodiploid Acute Lymphoblastic Leukemia (ALL) is a rare subtype of childhood ALL known to be associated with a poor prognosis. Currently, intensive chemotherapy and haematopoietic stem cell transplantation are recommended as the main therapeutic strategy for these patients. Previous studies showed that low-hypodiploid ALL frequently carry TP53 variants, the majority of which are germline mutations. This finding suggests that hypodiploid ALL may be a manifestation of underlying Li-Fraumeni syndrome, with an associated high risk for secondary tumors. We analyzed TP53 variants in the Italian cohort of hypodiploid pediatric ALL patients diagnosed between 2000 and 2019, to explore frequency and characteristics, as well as the potential role of germline variants in the therapeutic strategy. Patients were treated according to the AIEOP-BFM ALL2000 (n=16), ALL2009 (n=16) and ALL2017 (n=8) protocols. Methods. We performed a targeted Next Generation Sequencing (NGS) Nextera Flex DNA panel of 40 genes, including TP53, in a retrospective series of hypodiploid paediatric ALL Italian patients enrolled in four nationwide frontline protocols. Ploidy was defined based on DNA index (DNAi) and/or cytogenetics/FISH, and cases with DNAi5% and coverage 500X were considered. Bioinformatics analysis has been carried out by Sophia DDM software. NGS has been performed both in disease (hematopoietic) and germline (remission or buccal brush) tissues samples. Results. Nineteen TP53 variants were observed in 20/40 (50%) hypodiploid ALL patients, with 19/20 being low-hypodiploid ALL cases (DNAi between 0,6 and 0,8); 13/19 TP53 variants were known to be pathogenic whereas 6/19 were classified as Variant of Unknown Significance (VUS). Considering the VUS variants, 3/6 were missense, 1/6 frameshift and 2/6 in-frame ins/del. Notably, 13 patients out of 20 (65%) were found to carry a germline variant, while 5 patients presented a somatic variant; in 2 cases the remission sample was not available, but the VF Considering the 32 patients with at least 5 years of follow-up, EFS was not significantly different between TP53 wild type (47.1% ± 12.1) vs TP53 variant (51.9% ± 17,8) subgroups. According to MRD stratification criteria, the patients carrying a TP53 variant were classified as medium risk in 14/20, standard risk in 5/20 and HR in 1 case, not statistically different from TP53 wild type. Collection of data on secondary neoplasms in patients and their relatives in ongoing. Conclusion. Our data represent the largest low hypodiploid patient cohort tested so far, confirming the high frequency of deleterious TP53 mutations. Mutational testing of TP53 in patients with hypodiploid ALL is warranted, in order to ensure a proper genetic counseling for patients with germline mutations and their families, with tailored clinical surveillance (according to Li-Fraumeni Syndrome guidelines). The best therapeutic regimen for hypodiploid patients is still a matter of debate, with MRD at the end of induction and TP53 germline mutations potentially indicating a highest relevance in the indication to hematopoietic stem cell transplantation. Chemotherapy-only treatment could be indicated for MRD-low patients and HSCT for MRD-High, potentially considering a reduced conditioning regimen for TP53 mutated cases. Disclosures Locatelli: Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bellicum Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Miltenyi: Speakers Bureau; Medac: Speakers Bureau; Jazz Pharmaceeutical: Speakers Bureau. Rizzari:Sobi: Consultancy, Other: Advisory Board.

Background Macrophage activation syndrome (MAS) is a severe complication of rheumatologic conditions, mainly systemic juvenile idiopathic arthritis (sJIA), and is classified as a secondary form of hemophagocytic lymphohistiocytosis (HLH). Thrombotic microangiopathy (TMA) is a heterogeneous group of potentially fatal diseases characterized by microangiopathic hemolytic anemia, thrombocytopenia and organ injury. The association between TMA and HLH has been described only in single reports in renal transplant recipients1 and in two cases of virus-induced HLH2. TMA associated with MAS has never been reported so far Objectives To present the preliminary data from a multinational cohort of pediatric patients with MAS and TMA Methods The clinical charts of patients with MAS were retrospectively reviewed to identify the instances that were associated with TMA. Demographic, clinical and laboratory features at MAS and TMA onset, therapeutic interventions and outcome were collected. Results A total of 14 patients, 71.4% females, with MAS and TMA were collected. An underlying rheumatologic disease was reported in 9/14 (8 sJIA or sJIA-like illness and 1 systemic lupus erythematosus). The median age at MAS onset was 8.6 years. In 5 patients MAS and TMA occurred simultaneously, whereas in 4 TMA preceded and in 5 followed MAS. The main features at MAS and TMA onset are presented in Table. Low complement levels and reduced ADAMTS13 activity were observed in 75% and 43% of patients respectively. For MAS management, 85.7% of patients received high-dose corticosteroids and 71.4% cyclosporine; in 5 cases anakinra was added. TMA episodes were treated with plasma-exchange in 57.1% of patients; 7 patients were given biologics (1 rituximab and 6 eculizumab) with good results. Admission to the Intensive Care Unit was required in 85.7% of cases. All patients survived. Conclusion The association of MAS and TMA is a life-threatening condition, likely under-recognized. Clues to suspect TMA in a patient with MAS are the increase in LDH and decrease in platelet count out of proportion of other laboratory abnormalities, the drop in haptoglobin level, the finding of schistocytes in blood smear and the new onset of hematuria. Biologics, particularly rituximab and eculizumab, may offer an adjunctive therapeutic option for refractory cases. References [1] Esmaili H, et al. An update on renal involvement in hemophagocytic syndrome. J Nephropathol 2016; 2Fraga-Rodriguez GM, et al. Eculizumab in a child with atypical haemolytic uraemic syndrome and haemophagocytic lymphohistiocytosis triggered by cytomegalovirus infection. BMJ Case Rep2017. Disclosure of Interests Francesca Minoia: None declared, Jessica Tibaldi: None declared, Valentina Muratore: None declared, Romina Gallizzi: None declared, Claudia Bracaglia: None declared, Alessia Arduini: None declared, Elif Comak: None declared, Olga Vougiouka: None declared, Ralf Trauzeddel : None declared, Giovanni Filocamo: None declared, Concetta Micalizzi: None declared, Angelo Ravelli Grant/research support from: Angelini, AbbVie, Bristol-Myers Squibb, Johnson & Johnson, Novartis, Pfizer, Reckitt Benkiser, and Roche, Consultant for: Angelini, AbbVie, Bristol-Myers Squibb, Johnson & Johnson, Novartis, Pfizer, Reckitt Benkiser, and Roche, Speakers bureau: Angelini, AbbVie, Bristol-Myers Squibb, Johnson & Johnson, Novartis, Pfizer, Reckitt Benkiser, and Roche

Introduction Advances in paediatric oncology led to the increase in long-term survival, revealing the burden of therapy-related long-term side effects. We evaluated overall and cause-specific mortality in a large cohort of Italian childhood cancer survivors (CCSs) and adolescent cancer survivors identified through the off-therapy registry. Materials and methods CCSs alive 5 years after cancer diagnosis occurring between 1960 and 1999 were eligible; the last follow-up was between 2011 and 2014. Outcomes were reported as standardised mortality ratios (SMRs) and absolute excess risks (AERs). Results Among 12,214 CCSs, 1113 (9.1%) deaths occurred. Survival at 35 years since diagnosis was 87% (95% confidence interval [CI]: 86–88) and at 45 years was 81% (95% CI: 77–84). CCSs had an 11-fold increased risk of death (SMR 95% CI: 10.7–12), corresponding to an AER of 48 (95% CI: 45–51). Mortality decreased by 60% for survivors treated most recently (1990–1999). The most frequent causes of death were recurrence of the original cancer (56%), a subsequent neoplasm (19%) and cardiovascular diseases (5.8%). Among those who survived at least 15 years after diagnosis, a secondary malignancy was the leading cause of death. Conclusions This study confirms the impact of recent advances in anticancer therapy in reducing mortality, mainly attributable to recurrence but also to other causes. However, overall mortality continues to be higher than in the general population. A long-term follow-up is needed to prevent late mortality due to secondary neoplasms and non-neoplastic causes in CCSs.

Autoimmune lymphoproliferative syndrome (ALPS) is a congenital disorder that results in an apoptosis impairment of lymphocytes, leading to chronic lymphoproliferation and autoimmunity, mainly autoimmune cytopenias. FAS gene defects are often responsible for the disease, the phenotype of which can vary from asymptomatic/mild forms to severe disease. More rarely, defects are associated to other genes involved in apoptosis pathway, such as CASP10. Few data are available on CASP10-mutated patients. To date, two CASP10 mutations have been recognized as pathogenic (I406L and L258F) and others have been reported with controversial result on their pathogenicity (V410l, Y446C) or are known to be polymorphic variants (L522l). In this study, we evaluated apoptosis function in patients with an ALPS/ALPS-like phenotype carrying CASP10 variants. Molecular findings were obtained by next generation sequencing analysis of genes involved in immune dysregulation syndromes. Functional studies were performed after inducing apoptosis by FAS-ligand/TRIAL stimulation and analysing cell death and the function of CASP10, CASP8 and PARP proteins. We identified 6 patients with an ALPS (n = 2) or ALPS-like (n = 4) phenotype, carrying I406L (n = 1),V410l (n = 2),Y446C (n = 1) heterozygous CASP10 variants or the L522l polymorphisms (n = 2) associated with another polymorphic homozygote variant on CASP8 or a compound heterozygous mutation on TNFRSF13C. Apoptosis was impaired in all patients showing that such variants may play a role in the development of clinical phenotype.

Asparagine levels in cerebrospinal fluid and serum asparaginase activity were monitored in children with acute lymphoblastic leukemia treated with pegylated-asparaginase. The drug was given intravenously at a dose of 2,500 IU/m2 on days 12 and 26. Serum and cerebrospinal fluid samples obtained on days 33 and 45 were analyzed centrally. Since physiological levels of asparagine in the cerebrospinal fluid of children and adolescents are 4-10 μmol/L, in this study asparagine depletion was considered complete when the concentration of asparagine was ≤0.2 μmol/L, i.e. below the lower limit of quantification of the assay used. Over 24 months 736 patients (AIEOP n=245, BFM n=491) and 903 cerebrospinal fluid samples (n=686 on day 33 and n=217 on day 45) were available for analysis. Data were analyzed separately for the AIEOP and BFM cohorts and yielded superimposable results. Independently of serum asparaginase activity levels, cerebrospinal fluid asparagine levels were significantly reduced during the investigated study phase but only 28% of analyzed samples showed complete asparagine depletion while relevant levels, ≥1 μmol/L, were still detectable in around 23% of them. Complete cerebrospinal fluid asparagine depletion was found in around 5-6% and 33-37% of samples at serum asparaginase activity levels

Background Ultrasound-guided (USG) cannulation of the brachiocephalic vein (BCV) is gaining worldwide consensus for central venous access in children. This study reports a 20-month experience with this approach in children. Methods All patients who underwent percutaneous USG central venous catheter (CVC) positioning in the BCV between August 2013 and March 2015 have been included. Devices inserted during this period were open-ended, either single or double-lumen tunneled CVC. Our series was divided into three consecutive study periods in order to determine the relative incidence of repositioning and complications. Results During the study period, a total of 95 patients underwent 109 CVC insertions in the BCV. The median length of CVC duration was 230 days for a total of 23,212 catheter days. No major intraoperative complications occurred. Overall rate of CVC-related postoperative complications requiring repositioning or precocious removal was 0.90 per 1,000 catheter days and involved 21 CVC (19%, 95% confidence interval 13-28). These included 18 dislodgments, two infections, and one malfunction. Double-lumen CVCs represented the only significant risk factor for complications (52% complications-three per 1,000 catheter days). Conclusion USG supraclavicular cannulation of the BCV represents a safe approach for central line placement in children. It proved to be versatile, as it can be used in premature infants as well as in adolescents. Provided it is adopted by operators experienced in USG cannulation, we strongly suggest to resort to this approach as a first-line choice in children undergoing tunnelled central line placement for long-lasting therapy.

Summary The management of refractory autoimmune cytopenias in childhood is challenging due to the lack of established evidence on escalating treatments. The long-term efficacy of immunosuppressive drugs was evaluated in children with refractory autoimmune cytopenias referred to the Haematology Unit of the Gaslini Children's Hospital between 2001 and 2014. Patients were grouped into three categories: autoimmune lymphoproliferative syndrome (ALPS), ALPS-related syndrome (at least one absolute/primary additional criterion for ALPS) and primary autoimmune cytopenia (PAC, cytopenia with no other immunological symptoms/signs). Fifty-eight children (aged 1–16 years) entered the study: 12 were categorized with ALPS, 24 were ALPS-related and 22 had PAC. Five didn't receive treatment. Fifty-three were initially treated with steroids/intravenous immunoglobulin. Fourteen responded, whereas 39 did not. Of these 39 patients, 34 (87%) received mycophenolate mofetil (MMF) as second/further-line treatment and 22 (65%) responded. Within these 34 subjects, ALPS patients responded better (11/11, 100%) than the two other groups pooled together (11/23, 48%; P = 0·002). Sirolimus was given as second/further-line treatment to 16 children, and 12 (75%) responded, including 8 who previously failed MMF therapy. Median follow-up was 3·46 years. MMF and Sirolimus were well-tolerated and enabled partial/complete and sustained remission in most children. These drugs may be successfully and safely used in children with refractory autoimmune cytopenias with or without ALPS/ALPS-related disorders and may represent a valid second/further line option.

OBJECTIVE: To develop and validate a diagnostic score that assists in discriminating primary hemophagocytic lymphohistiocytosis (pHLH) from macrophage activation syndrome (MAS) related to systemic juvenile idiopathic arthritis. STUDY DESIGN: The clinical, laboratory, and histopathologic features of 362 patients with MAS and 258 patients with pHLH were collected in a multinational collaborative study. Eighty percent of the population was assessed to develop the score and the remaining 20% constituted the validation sample. Variables that entered the best fitted model of logistic regression were assigned a score, based on their statistical weight. The MAS/HLH (MH) score was made up with the individual scores of selected variables. The cutoff in the MH score that discriminated pHLH from MAS best was calculated by means of receiver operating characteristic curve analysis. Score performance was examined in both developmental and validation samples. RESULTS: Six variables composed the MH score: age at onset, neutrophil count, fibrinogen, splenomegaly, platelet count, and hemoglobin. The MH score ranged from 0 to 123, and its median value was 97 (1st-3rd quartile 75-123) and 12 (1st-3rd quartile 11-34) in pHLH and MAS, respectively. The probability of a diagnosis of pHLH ranged from 99% for a score of =123. A cutoff value of =60 revealed the best performance in discriminating pHLH from MAS. CONCLUSION: The MH score is a powerful tool that may aid practitioners to identify patients who are more likely to have pHLH and, thus, could be prioritized for functional and genetic testing.

To the editor: Reinduction therapy (also known as delayed intensification, DI) is an essential part of childhood acute lymphoblastic leukemia (ALL) treatment.[1][1],[2][2] In Berlin-Frankfurt-Munster (BFM) studies, it includes same/similar drugs as those employed in induction therapy. The Children

Febrile neutropenia (FN) represents a life-threatening complication in hematological malignancies. Its etiology is most often due to infections even though FN of other origins, such as tumor-related fever and non-infectious inflammation, should rapidly be ruled out. Initially, C-reactive protein and, more recently, procalcitonin (PCT) have been proposed as useful biomarkers for differential diagnosis. PCT was shown to be a good biomarker of bacterial infections and their clinical outcomes. Definition of standard cut-offs and design of PCT-guided treatment protocols remain however to be defined. Areas covered: In this review, highlights on the current clinical use of PCT and its potential role as a diagnostic tool have been discussed by a panel of physicians from different areas of expertise. We provide current clinical evidence that PCT has been shown to be a reliable biomarker to differentiate fever of bacterial origin from other causes. Moreover, the Authors convened to a round-table to discuss their 'real-life experience' and offer their recommendations by a Delphi survey. Expert commentary: PCT has an important clinical role in FN. Issues such as the validation of a specific decision algorithm that includes PCT to monitor antibiotic choice and treatment duration will be addressed in prospective studies.

To the editor: Essential thrombocythemia (ET) is a myeloproliferative neoplasm (MPN) that mainly affects middle-aged patients. Although pediatric cases occur, they are rare, and their molecular features considerably differ from the adult counterparts: JAK2 V617F mutation occurs in only 25% of cases

Gaucher disease (GD) is caused by an enzyme deficiency that leads to the accumulation of glycolipids in various organs. Although the signs and symptoms of GD emerge in childhood in the majority of patients, the disease often remains unrecognized for many years with delay of benefits of therapy or development of irreversible complications. Based on published data and data from the International Collaborative Gaucher Group Registry, an algorithm has been drafted for early diagnosis of GD in pediatric patients. It will help hematologists in promoting a timely diagnosis and early access to therapy for pediatric patients with GD.