Search

International audience; Fanconi anemia (FA) patients experience chromosome instability, yielding hematopoietic stem/progenitor cell (HSPC) exhaustion and predisposition to poor-prognosis myeloid leukemia. Based on a longitudinal cohort of 335 patients, we performed clinical, genomic, and functional studies in 62 patients with clonal evolution. We found a unique pattern of somatic structural variants and mutations that shares features of BRCA-related cancers, the FA-hallmark being unbalanced, microhomology-mediated translocations driving copy-number alterations. Half the patients developed chromosome 1q gain, driving clonal hematopoiesis through MDM4 trisomy downmodulating p53 signaling later followed by secondary acute myeloid lukemia genomic alterations. Functionally, MDM4 triplication conferred greater fitness to murine and human primary FA HSPCs, rescued inflammation-mediated bone marrow failure, and drove clonal dominance in FA mouse models, while targeting MDM4 impaired leukemia cells in vitro and in vivo. Our results identify a linear route toward secondary leukemogenesis whereby early MDM4-driven downregulation of basal p53 activation plays a pivotal role, opening monitoring and therapeutic prospects.

Ten to fifteen percent of children with acute lymphoblastic leukemia (ALL) relapse following treatment. Of these, less than 2% display ophthalmic relapses, which owing to their scarcity, are largely undocumented, leaving clinicians with few diagnostic and therapeutic recommendations, despite serious functional sequelae. We conducted a French multicenter retrospective study to collect all clinical, radiological, biological, and therapeutic data, and outcomes for children with ALL ophthalmic relapses. From 2000 to 2020, 20 ophthalmic relapses occurring after first-line therapy performed before January 1

SUMMARYChanges in lymphocyte production patterns occurring across human ontogeny remain poorly defined. In this study, we demonstrate that human lymphopoiesis is supported by three waves of embryonic, fetal, and postnatal multi-lymphoid progenitors (MLPs) differing in CD7 and CD10 expression and their output of CD127-/+early lymphoid progenitors (ELP). Our results reveal that, like the fetal-to-adult switch in erythropoiesis, transition to postnatal life coincides with a shift from multilineage to B lineage-biased lymphopoiesis and an increase in production of CD127+ELPs which persists until puberty. A further developmental transition is observed in elderly individuals where B-cell differentiation bypasses the CD127+compartment and branches directly from CD10+MLPs. Functional analyses indicate that these changes are determined at the level of the hematopoietic stem cell. Besides reconciling controversies about the identity and function of human MLPs, these results may shed light on the causes of age-related differences in the incidence of lymphoblastic leukemia.

Gain-of-function mutations in the protein-tyrosine phosphatase SHP2 are the most frequently occurring mutations in sporadic juvenile myelomonocytic leukemia (JMML) and JMML-like myeloproliferative neoplasm (MPN) associated with Noonan syndrome (NS). Hematopoietic stem and progenitor cells (HSPCs) are the disease propagating cells of JMML. Here, we explored transcriptomes of HSPCs with SHP2 mutations derived from JMML patients and a novel NS zebrafish model. In addition to major NS traits, CRISPR/Cas9 knock-in Shp2Juvenile myelomonocytic leukaemia is a childhood blood cancer. It is more common in children with a genetic condition called Noonan Syndrome, which causes problems with development in many parts of the body. The most frequent cause is a mutation in a protein called Src homology region 2 domain-containing phosphatase-2, or SHP2 for short. Juvenile myelomonocytic leukaemia starts in the stem cells that normally become blood cells. In children with Noonan Syndrome, these cells show signs of problems before leukaemia begins. Recreating Noonan Syndrome in an animal could shed light on how this childhood cancer develops, but doing this is not straightforward. One option is to use zebrafish, a species of fish in which the embryos are transparent, allowing scientists to watch their blood cells developing under a microscope. They also share many genes with humans, including SHP2. Solman et al. genetically modified zebrafish so they would carry one of the most common mutations seen in children with Noonan Syndrome in the SHP2 protein. The fish had many of the typical features of the condition, including problems producing blood cells. Single cell analysis of the stem cells that become these blood cells showed that, in the mutated fish, these cells had abnormally high levels of activity in genes involved in inflammation. Treating the fish with an anti-inflammatory drug, dexamethasone, reversed the problem. When Solman et al. investigated stem cells from human patients with juvenile myelomonocytic leukaemia, they found the same high levels of activity in inflammatory genes. The current treatment for juvenile myelomonocytic leukaemia is a stem cell transplant, which is only successful in around half of cases. Finding a way to prevent the cancer from developing altogether could save lives. This new line of zebrafish allows researchers to study Noonan Syndrome in more detail, and to test new treatments. A next step could be to find out whether anti-inflammatory drugs have the same effects in mammals as they do in fish.

To investigate whether ontogeny-related features determine the pediatric specificity in juvenile myelomonocytic leukemia (JMML), we compared the gene expression profile of hematopoietic progenitor cells sorted from JMML to their healthy counterparts isolated at different stages of ontogeny. Two groups of JMML were identified. The JMML in the first group had a fetal-like expression profile. Their progenitors showed a stronger monocytic identity than other JMML or healthy postnatal progenitors with overexpression of monocytic/dendritic, inflammasome and innate immunity markers, reminiscent of the monocyte-biased myelopoiesis characterizing physiologic fetal hematopoiesis. The second group, although clustering apart from healthy prenatal and post-natal fractions, was characterized by aberrant expression of the master oncofetal regulator LIN28B, suggesting developmental dysregulation. LIN28B expression was associated with DNA hypermethylation. Analysis of a large cohort of 108 patients with JMML showed that a high LIN28 expression was correlated to a poor outcome. Our findings highlight a strong but complex link between JMML and development, and will be important to guide future treatment strategies in this rare but severe leukemia.

Objective The conduct of a medical interview is a challenging skill, even for the most qualified physicians. Since a training is needed to acquire the necessary skills to conduct an interview with a patient, we compared role-play with standardized patients (SP) training and a conventional lecture for the acquisition of communications skills in undergraduate medical students.Methods An entire promotion of third year undergraduate medical students, who never received any lessons about communications skills, were randomized into 4 arms: 1) SP 2 months before the testing of medical communications skills (SP); 2) conventional lecture 2 months before the testing (CL); 3) two control groups (CG) without any intervention, tested either at the beginning of the study or two months later. Students were blindly assessed by trained physicians with a modified 17-items Calgary-Cambridge scale.Results 388 students (98.7%) participated. SP performed better than CL, with significant statistical differences regarding 5 skills: the use of open and closed questions, encouraging patient responses, inviting the patient to clarify the missing items, encouraging of the patient’s emotions, and managing the time and the conduct of the interview. The SP group specifically improved communications skills between the SP training and testing sessions regarding 2 skills: the use of open and closed questions and encouraging patient responses. No improvements in communications skills were observed in CG between the two time points, ruling out a possible time effect.Conclusion Role-play with standardized patients appears more efficient than conventional lecture to acquire communication skills in undergraduate medical students.

International audience; Context A negative association between a history of allergy and childhood acute lymphoblastic leukaemia (ALL) has been reported in previous studies, but remains debated. This work aimed to investigate this association accounting for genetic polymorphisms of the Th2 pathway cytokines (IL4, IL10, IL13 and IL4-receptor (IL4R)). Methods Analyses were based on the French case-control study ESTELLE (2010-2011). The complete sample included 629 ALL cases and 1,421 population-based controls frequency-matched on age and gender. The child's medical history was collected through standardised maternal interview. Biological samples were collected, and genotyping data were available for 411 cases and 704 controls of European origin. Odds ratios (OR) were estimated using unconditional regression models adjusted for potential confounders. Results In the complete sample, a significant inverse association was observed between ALL and reported history of allergic rhinitis or sinusitis (OR=0.65 [0.42-0.98]; p= 0.04), but there was no obvious association with allergies overall. There was an interaction between genetic polymorphisms in IL4 and IL4R (pinteraction=0.003), as well as a gene-environment interaction between IL4R-rs1801275 and a reported history of asthma (IOR=0.23; pint=0.008) and eczema (IOR= 0.47; pint=0.06). We observed no interaction with the candidate polymorphisms in IL4 and IL13. Conclusion These results suggest that the association between allergic symptoms and childhood ALL could be modified by IL4R-rs1801275, and that this variant could also interact with a functional variant in IL4 gene. While they warrant confirmation, these results could help understand the pathological mechanisms under the reported inverse association between allergy and childhood ALL.

Aberrant signaling through pathways controlling cell response to extracellular stimuli constitutes a central theme in disorders affecting development. Signaling through RAS and the MAPK cascade controls a variety of cell decisions in response to cytokines, hormones, and growth factors, and its upregulation causes Noonan syndrome (NS), a developmental disorder whose major features include a distinctive facies, a wide spectrum of cardiac defects, short stature, variable cognitive impairment, and predisposition to malignancies. NS is genetically heterogeneous, and mutations in more than ten genes have been reported to underlie this disorder. Despite the large number of genes implicated, about 10%-20% of affected individuals with a clinical diagnosis of NS do not have mutations in known RASopathy-associated genes, indicating that additional unidentified genes contribute to the disease, when mutated. By using a mixed strategy of functional candidacy and exome sequencing, we identify RRAS2 as a gene implicated in NS in six unrelated subjects/families. We show that the NS-causing RRAS2 variants affect highly conserved residues localized around the nucleotide binding pocket of the GTPase and are predicted to variably affect diverse aspects of RRAS2 biochemical behavior, including nucleotide binding, GTP hydrolysis, and interaction with effectors. Additionally, all pathogenic variants increase activation of the MAPK cascade and variably impact cellmorphology and cytoskeletal rearrangement. Finally, we provide a characterization of the clinical phenotype associated with RRAS2 mutations.

10006 Background: Access to innovative anticancer therapies for children, adolescents and young adults within clinical trials in France is steadily increasing in the last years. However, current clinical trials portfolios are still inadequate and thus pediatric hemato-oncologists regularly prescribe innovative medicines outside their marketing authorization, and/or experimental drugs through compassionate use. Methods: The Secured Access to innovative medicines for CHildren with cAncer (SACHA) is a French prospective observational study developed by the French Society of Pediatric Oncology (SFCE) with Gustave Roussy as the legal sponsor to prospectively collect real-world safety and activity data of innovative therapies administered to patients ≤ 25 years-old with pediatric malignancies (solid tumor or leukemia) or other related conditions, either on compassionate use of experimental drugs or off-label use of anti-cancer medicines that have been first approved in adults after 2007. Prior to SACHA inclusion, multicenter tumor board discussion defining best available therapeutic options for each patient with a relapsed malignancy is mandatory. Results: The SACHA study opened in March 2020 and by February 2022, 283 patients have been included from 29/31 SFCE recruiting centers; median age: 11.0 years (range: 0.3-24.4). Main cancer types were central nervous system (CNS) tumors (47%), followed by non-CNS tumors (40%) and leukemias (13%). Innovative therapies prescribed in > 10 patients with reported objective response rate (ORR) and related CTCAE v.5 grade ≥2 clinical and/or grade ≥3 biological adverse drug reactions (ADRs) are described in Table. Conclusions: SACHA confirms the feasibility of this type of prospective real word registry, with a high participation of French centers. Based on this French experience, the Innovative Therapies for Children with Cancer (ITCC) consortium is currently developing a “SACHA International Project” to be opened in ITCC and collaborating countries. [Table: see text]

Depuis l’émergence de l’infection à SARS-CoV-2, de très nombreuses recommandations ont été émises. Cependant la nature de la maladie et la spécificité du traitement des leucémies aiguës lymphoblastiques de l’enfant et de l’adolescent ont conduit le Comité Leucémies de la Société Française de lutte contre les Cancers et leucémies de l’Enfant et de l’adolescent (SFCE) à proposer des recommandations propres. Voici la deuxième version de ces recommandations prenant en compte l’évolution des connaissances sur l’infection COVID19.

Juvenile myelomonocytic leukemia (JMML) is a rare aggressive myelodysplastic/myeloproliferative neoplasm of early childhood, initiated by RAS-activating mutations. Genomic analyses have recently described JMML mutational landscape; however, the nature of JMML-propagating cells (JMML-PCs) and the clonal architecture of the disease remained until now elusive. Combining genomic (exome, RNA-seq), Colony forming assay and xenograft studies, we detect the presence of JMML-PCs that faithfully reproduce JMML features including the complex/nonlinear organization of dominant/minor clones, both at diagnosis and relapse. Further integrated analysis also reveals that although the mutations are acquired in hematopoietic stem cells, JMML-PCs are not always restricted to this compartment, highlighting the heterogeneity of the disease during the initiation steps. We show that the hematopoietic stem/progenitor cell phenotype is globally maintained in JMML despite overexpression of CD90/THY-1 in a subset of patients. This study shed new lights into the ontogeny of JMML, and the identity of JMML-PCs, and provides robust models to monitor the disease and test novel therapeutic approaches.

International audience; Since the emergence of the SARS-CoV-2 infection many recommendations have been made. However the very nature of acute lymphoblastic leukemias and their treatment in children and adolescents led the Leukemia Committee of the French Society for the fight against cancers and leukemias in children and adolescents (SFCE) to propose more specific recommendations even if data for this population are still scarce. They may have to evolve according to the rapid evolution of knowledge on COVID-19.

Introduction Data regarding real-world impact on cancer clinical research during COVID-19 are scarce. We analysed the impact of the COVID-19 pandemic on the conduct of paediatric cancer phase I-II trials in Europe through the experience of the Innovative Therapies for Children with Cancer (ITCC). Methods A survey was sent to all ITCC-accredited Early-Phase Clinical Trial Hospitals including questions about impact on staff activities, recruitment, patient care, supply of investigational products and legal aspects, between 1/March and 30/April/2020. Results Thirty-one out of 53 hospitals from 12 countries participated. Challenges reported included staff constraints (30% drop), reduction in planned monitoring activity (67% drop of site initiation visits and 64% of monitoring visits) and patient recruitment (61% drop compared to 2019). The percentage of phase I, phase II trials and molecular platforms closing to recruitment in at least one site was 48.5%, 61.3% and 64.3%, respectively. Additionally, 26% of sites had restrictions on performing trial assessments due to local contingency plans. Almost half of the units suffered impact upon pending contracts. Most hospitals (65%) are planning on improving organizational and structural changes. Conclusion The study reveals a profound disruption of paediatric cancer early phase clinical research due to the COVID-19 pandemic across Europe. Reported difficulties affected both patient care and monitoring activity. Efforts should be made to reallocate resources to avoid lost opportunities for patients and to allow the continued advancement of oncology research. Identified adaptations to clinical trial procedures may be integrated to increase preparedness of clinical research to futures crises., Highlights • The COVID-19 pandemic has profoundly disrupted paediatric cancer clinical research. • A drastic drop in recruitment in phase I/II trials compared to 2019 was observed. • Current research needs reorganization to avoid loss of opportunities for children.

La leucemie myelomonocytaire juvenile (LMMJ) est un syndrome myelodysplasique/myeloproliferatif agressif de la petite enfance lie a une hyperactivation de la voie de signalisation RAS/MAP-kinase. Il s’agit d’une hemopathie rare et difficile a diagnostiquer du fait de la grande heterogeneite des presentations cliniques et de l’absence de test diagnostique specifique. Un tiers des LMMJ surviennent dans un contexte de syndromes predisposants lies a une hyperactivation constitutive de la voie RAS, les RASopathies, qui necessitent une prise en charge particuliere. Il est donc indispensable, chez tout patient avec LMMJ, de mener une enquete genetique constitutionnelle, clinique et biologique. La meilleure connaissance des bases moleculaires des LMMJ a permis, ces dernieres annees, d’ameliorer la stratification therapeutique des patients, et il est donc aujourd’hui licite de proposer a certains patients, sur les bases de leur analyse moleculaire tumorale et constitutionnelle, une surveillance clinique et biologique simple. Cependant, un grand nombre de patients doivent toujours avoir recours a un traitement curateur. Le traitement de reference reste aujourd’hui la greffe de cellules souches hematopoietiques qui permet de guerir environ 50 % des enfants. Les espoirs se concentrent sur les agents demethylants et sur l’utilisation de therapeutiques ciblees sur les voies de signalisation deregulees dans la LMMJ.

No abstract available

Resume La voie de signalisation cellulaire des RAS/MAP Kinases (RAS/MAPK) joue un role majeur sur le devenir des cellules en participant a la regulation de la proliferation, de la differentiation et de la survie cellulaire. Les mutations des genes RAS et des genes de leurs effecteurs et regulateurs participent a l’oncogenese de nombreux cancers sporadiques. Par ailleurs, au cours de ces 20 dernieres annees, des mutations constitutionnelles de ces memes genes ont ete identifiees dans plusieurs syndromes cliniques associant, de facon variable, une cardiopathie ou une cardiomyopathie, une dysmorphie, une deficience intellectuelle, des anomalies cutanees et un retard de croissance. Ces differents syndromes (syndrome de Noonan, de Costello, syndrome cardio-facio-cutane…), lies a une deregulation de la voie RAS/MAPK, sont aujourd’hui regroupes sous le terme RASopathie. En plus des anomalies du developpement qui les caracterisent, les RASopathies engendrent un risque accru de tumeurs malignes dans l’enfance. Ces patients doivent donc beneficier d’une surveillance et d’une prise en charge adaptees a ce risque.

Juvenile myelomonocytic leukemia (JMML) is a rare aggressive myelodysplastic/myeloproliferative neoplasm of early childhood, initiated by RAS-activating mutations. Genomic analyses have recently described JMML mutational landscape; however, the nature of JMML-propagating cells (JMML-PCs) and the clonal architecture of the disease remained until now elusive. Combining genomic (exome, RNA-seq), Colony forming assay and xenograft studies, we detect the presence of JMML-PCs that faithfully reproduce JMML features including the complex/nonlinear organization of dominant/minor clones, both at diagnosis and relapse. Further integrated analysis also reveals that although the mutations are acquired in hematopoietic stem cells, JMML-PCs are not always restricted to this compartment, highlighting the heterogeneity of the disease during the initiation steps. We show that the hematopoietic stem/progenitor cell phenotype is globally maintained in JMML despite overexpression of CD90/THY-1 in a subset of patients. This study shed new lights into the ontogeny of JMML, and the identity of JMML-PCs, and provides robust models to monitor the disease and test novel therapeutic approaches.

Purpose: Hypomethylating agents are approved in adults with Acute Myeloid Leukemia (AML) or Myelodysplastic Syndrome (MDS). By contrast, data in pediatric hematologic malignancies are scarce. Herein, we report the off-label administration of Azacitidine (Aza) in a cohort of children, adolescents and young adults (AYA). Methods: Patients from Robert-Debré, Saint-Louis and Armand-Trousseau University Hospitals (Assistance Publique-Hôpitaux de Paris), 25 year-old or younger at initiation of treatment and who received Aza between 2009 and 2019 were included. Data on indication, efficacy and toxicity of the treatment were retrospectively collected. Results: As 3 patients (pts) were treated twice with Aza at different stages of their disease, 35 treatments in 32 patients were analyzed. Median age at diagnosis was 11.7 y (range 0.1-22.4). Diagnosis were: 16 Acute Myeloid Leukemias (AML), 6 Juvenile Myelomonocytic Leukemias (JMML), 7 Myelodysplastic Syndromes (MDS), 2 Mixed Phenotype Acute Leukemias (MPAL) and 1 Interdigitating Dendritic Cells Sarcoma. Aza was administrated after a median of 2 lines of treatment (range 0-6) and front line in 5 out of 32 pts (16%; MDS = 4, JMML = 1). Concomitant therapy was administrated in 15/35 treatments (43%) (Sorafenib = 6, Gemtuzumab Ozogamicin = 2, donor lymphocyte infusions = 2, other = 5). Fourteen out of 35 treatments (40%) were delivered in patients with a history of hematopoietic stem cell transplantation (HSCT). Aza was administrated either intravenously (n = 11) or subcutaneously (n = 24) at a dose of 75mg/m² for 7 (20/35, 57%) or 5 (6/35, 17%) consecutive days every 28 days, i.e. same daily dose as in adults; at reduced doses (≤ 50mg/m²) in 3/35 patients; at a dosing scheme varying from one cycle to another in 6/35 patients. Patients received a median of 3 cycles of Aza per treatment (range 1-31). A total of 137 cycles was delivered. Aza was well tolerated with only 5/137 cycles delayed due to hematological (n = 3) or non-hematological (n = 2) toxicity. Aza was discontinued due to toxicity in 2/137 cycles (1 rectal bleeding, 1 severe sepsis). Anemia was noted in 68/130 cycles (52%), thrombocytopenia in 68/128 cycles (53%), neutropenia in 84/127 cycles (66%) and febrile neutropenia in 25/131 cycles (19%). Two grade 5 side effects were observed: 1 patient died from cerebral hemorrhage in a context of anti-platelet poly-immunization, another from septic shock in a context of neutropenia. Most common non-hematological side effects included: nausea, vomiting, diarrhea, subcutaneous injections lesions (local inflammation or hematoma) and infections. Responses to Aza are detailed in the attached table. Best responses to Aza included: 2 complete remissions (CR) both after 3 cycles, 3 CR with incomplete hematologic recovery (CRi) after a median of 2 cycles (range 1-2), 2 partial remissions (PR) after 2 and 3 cycles, 6 stable diseases (SD) during a median of 2 cycles (range 2-12) and 2 hematologic improvements. Overall response rate (sum of CR, CRi, PRs), was 19% (6/32) (3 non evaluable responses). Three out of the 6 patients treated with Aza combined with Sorafenib (AML = 4, MPAL = 2) obtained a response (CR: 2, CRi: 1). The association led to HSCT for 2 of them; the third patient had a CR maintained almost 3 years without HSCT, before relapsing on therapy. One patient with MDS had a SD for 12 months after palliative treatment with Aza. Overall, Aza treatment allowed to proceed to HSCT in 8 out of 32 patients (25%), 7 out of 8 proceeding to a first HSCT [CR: 1 patient, CRi: 3 patients, PR: 2 patients, SD: 1 patient, progressive disease: 1 patient]. These 8 pts included: 4 pts with AML, alive in CR after a median follow-up of 29.5 months (2 of them received concomitant targeted therapy); 2 pts with JMML (1 alive in CR after a follow-up of 25 months); 2 pts with MDS (both died, 7 and 30 months after Aza initiation). Finally, 24 out of 32 patients died and overall survival at 5 years was 23% (IC95% [11;48]) with no difference according to diagnosis. Conclusion: In a cohort of pediatric and AYA patients with heavily pretreated myeloid malignancies, Aza was well tolerated, and allowed to bridge 25% of patients to HSCT. Further prospective studies are needed to explore combination of Aza with targeted therapy in pediatric patients. Disclosures Boissel: NOVARTIS: Consultancy.

The early persistence of minimal residual disease (MRD) is considered a poor prognostic factor indicative of chemoresistance in acute lymphoblastic leukemia. In French children, chemosensitivity is assessed at day 21 post-induction by cytomorphology. Here, it was investigated whether a more precise evaluation could be obtained at this time point with multiparameter flow cytometry (MFC). This study enrolled 123 children with de novo acute lymphoblastic leukemia. MRD0 was investigated at day 21 in MFC with a combination of antibodies based on the immunophenotype of diagnosis. It was also evaluated at day 35 by immunoglobulin/T-cell receptor quantitative real-time polymerase chain reaction (MRD1). Three risk groups could be delineated based on MRD0. Patients with MFC/MRD0 levels >10-2 (n = 25) were considered high risk, those with levels between 10-2 and 10-4 (n = 46) intermediate risk, and those

Background Infants with Noonan syndrome (NS) are predisposed to developing juvenile myelomonocytic leukaemia (JMML) or JMML-like myeloproliferative disorders (MPD). Whereas sporadic JMML is known to be aggressive, JMML occurring in patients with NS is often considered as benign and transitory. However, little information is available regarding the occurrence and characteristics of JMML in NS. Methods and results Within a large prospective cohort of 641 patients with a germline PTPN11 mutation, we identified MPD features in 36 (5.6%) patients, including 20 patients (3%) who fully met the consensus diagnostic criteria for JMML. Sixty percent of the latter (12/20) had severe neonatal manifestations, and 10/20 died in the first month of life. Almost all (11/12) patients with severe neonatal JMML were males. Two females who survived MPD/JMML subsequently developed another malignancy during childhood. Although the risk of developing MPD/JMML could not be fully predicted by the underlying PTPN11 mutation, some germline PTPN11 mutations were preferentially associated with myeloproliferation: 10/48 patients with NS (20.8%) with a mutation in codon Asp61 developed MPD/JMML in infancy. Patients with a p.Thr73Ile mutation also had more chances of developing MPD/JMML but with a milder clinical course. SNP array and whole exome sequencing in paired tumoral and constitutional samples identified no second acquired somatic mutation to explain the occurrence of myeloproliferation. Conclusions JMML represents the first cause of death in PTPN11 -associated NS. Few patients have been reported so far, suggesting that JMML may sometimes be overlooked due to early death, comorbidities or lack of confirmatory tests.

Juvenile myelomonocytic leukemias (JMML) are rare but severe myelodysplastic and myeloproliferative neoplasms of infancy. They represent about 10 new cases per year in France and preferentially affect males. JMML are all stem cell diseases the common denominator of which is RAS pathway dysregulation, due to mutations in RAS (NRAS, KRAS) or RAS regulatory components (PTPN11, NF1 or CBL). This leads to an hypersensivity of myeloid progenitors to GM-CSF (granulo-macrophagic colony stimulating factor) which induces in turn excessive monocytic and macrophagic proliferation in blood and bone marrow. All organs can be infiltrated by this monocytic proliferation leading to multisystemic failure. Blast crisis with transformation into acute myeloid leukemia occurs in one third of patients. A salient feature of JMML is their frequent association with predisposition syndromes such as Noonan syndrome, neurofibromatosis and CBL syndrome, which are developmental diseases associated with a constitutional RAS pathway deregulation, now grouped under the name RASopathies. Clinical heterogeneity makes JMML diagnosis difficult. Splenomagaly is the most constant sign. Palor, adenopathy, respiratory or cutaneous symptoms can also be present. Blood smear shows monocytosis (>1×10(9)/L) presence of myeloid progenitors and abnormal basophils. The demonstration of an endogeneous in vitro growth of myeloid progenitors although not very specific can help JMML diagnosis. Nowadays, genetic typing has to be included in the workup of JMML diagnosis and allows to evidence a mutation in more than 90% of cases. JMML have a poor prognosis. The only curative treatment is bone marrow transplantation but approximately 35% of patients relapse. JMML clinical course is highly heterogeneous and unpredictable. Some rare patients have an indolent evolution or even spontaneous remission. Age over two years, thrombopenia below 33×10(9)/L and high foetal hemoglobin (HbF) level for age are poor prognosis criteria but hardly predict individual outcome. Several research directions are currently being explored to improve prognosis prediction and provide more effective targeted treatments.

In hematopoietic cells with a germline mutation of CBL , loss of heterozygosity is not a signature of juvenile myelo-monocytic leukemia

Pediatric patients with high-risk (HR), refractory disease or early relapse, still have a dismal prognosis and therefore innovative salvage approaches are needed in this setting. Allogeneic stem ce...

International audience; Noonan syndrome is associated with a range of malignancies including acute lymphoblastic leukemia (ALL). However, little information is available regarding the frequency, natural history, characteristics and prognosis of ALL in Noonan syndrome or RASopathies in general. Cross-referencing data from a large prospective cohort of 1176 patients having a molecularly confirmed RASopathy with data from the French childhood cancer registry allowed us to identify ALL in 6 (0.5%) patients including 4/778 (0.5%) with a germline PTPN11 mutation and 2/94 (2.1%) with a germline SOS1 mutation. None of the patients of our series with CFC syndrome (with germline BRAF or MAP2K1/MAP2K2 mutation - n = 121) or Costello syndrome (with HRAS mutation - n = 35) had an ALL. A total of 19 Noonan-ALL were gathered by adding our patients to those of the International Berlin-Munster-Frankfurt (I-BFM) study group and previously reported patients. Strikingly, all Noonan-associated ALL were B-cell precursor ALL, and high hyperdiploidy with more than 50 chromosomes was found in the leukemia cells of 13/17 (76%) patients with available genetics data. Our data suggest that children with Noonan syndrome are at higher risk to develop ALL. Like what is observed for somatic PTPN11 mutations, NS is preferentially associated with the development of hyperdiploid ALL that will usually respond well to chemotherapy. However, Noonan syndrome patients seem to have a propensity to develop post therapy myelodysplasia that can eventually be fatal. Hence, one should be particularly cautious when treating these patients.

This single-center retrospective study reported the outcome of 19 children treated with a reduced-intensity conditioning (RIC) regimen prior to allogeneic stem cell transplantation (allo-SCT), for hematologic malignancies (n = 17), bone marrow failure (n = 1), and neuroblastoma (n = 1). Children were ineligible for standard myeloablative conditioning because of severe comorbidities (n = 9), a previous auto or allo-SCT (n = 7) or a prior history of extensive chemotherapy (n = 3). All patients underwent a fludarabine-based RIC regimen, and received grafts from matched-related donors (n = 5), match-unrelated donors (n = 6), or unrelated cord blood (UCB, n = 8). In this series, two patients treated with UCB failed to engraft and 63% achieved full donor chimerism at day 100 after allo-SCT. With a median follow-up of 537 d (range, 115-4136), treatment-related mortality was 16% and overall survival was 47%. The principal cause of death was disease relapse (n = 7). Acute graft versus host disease (GVHD) occurred in 53% of patients, while only 10% developed extensive chronic GVHD. Overall, results from this series suggest that RIC allo-SCT can be a valid alternative treatment option in unfit children with malignant hematological diseases. Prospective studies are needed to enlarge pediatric experience in this domain and better identify those children more suitable for a RIC allo-SCT approach.

International audience; Juvenile myelomonocytic leukemia (JMML) is a rare and severe myelodysplastic and myeloproliferative neoplasm of early childhood initiated by germline or somatic RAS-activating mutations. Genetic profiling and whole-exome sequencing of a large JMML cohort (118 and 30 cases, respectively) uncovered additional genetic abnormalities in 56 cases (47%). Somatic events were rare (0.38 events/Mb/case) and restricted to sporadic (49/78; 63%) or neurofibromatosis type 1 (NF1)-associated (8/8; 100%) JMML cases. Multiple concomitant genetic hits targeting the RAS pathway were identified in 13 of 78 cases (17%), disproving the concept of mutually exclusive RAS pathway mutations and defining new pathways activated in JMML involving phosphoinositide 3-kinase (PI3K) and the mTORC2 complex through RAC2 mutation. Furthermore, this study highlights PRC2 loss (26/78; 33% of sporadic JMML cases) that switches the methylation/acetylation status of lysine 27 of histone H3 in JMML cases with altered RAS and PRC2 pathways. Finally, the association between JMML outcome and mutational profile suggests a dose-dependent effect for RAS pathway activation, distinguishing very aggressive JMML rapidly progressing to acute myeloid leukemia.

This prospective study aimed to assess the incidence of silent hypersensitivity to Escherichia coli asparaginase in the treatment of acute lymphoblastic leukemia (ALL). Thirty-three children with newly diagnosed ALL were included in the study and treated according to the FRALLE 2000 protocol. The 'A group' (n = 18) differed from the 'B-T group' (n = 15) by a less intensive chemotherapy, the absence of concurrent prednisone therapy, and different asparaginase administration modalities during the second intensification. Asparagine, asparaginase activity, and anti-asparaginase antibodies were measured in each phase before the next injection of asparaginase. Eighteen percent of children presented a silent hypersensitivity. Most of them were in the 'B-T group' (p = 0.07), and maintained low antibody titers throughout the treatment. Clinical hypersensitivity was statistically more frequent in group A (p = 0.002), and allergy occurred mainly during the second intensification when antibody concentrations were significantly increased. We did not find any significant difference between asparaginase activity or asparagine depletion between the silent hypersensitivity and clinical allergy groups. In all, the results of this study suggest that chemotherapy and corticosteroid therapy associated with asparaginase treatment can lower antibody production and contribute to maintaining a silent hypersensitivity state.

Allogeneic hematopoietic stem cell transplantation (allo-SCT) is a treatment option for relapsed anaplastic large cell lymphoma (ALCL) in children, but reports on its efficacy in this disease are still limited. We analyzed data concerning 34 patients under 18 years of age prospectively registered in the French SFGM-TC database, who had undergone an allo-SCT for the treatment of ALK+ ALCL between 1993 and 2011. At transplant, 28 patients (82.4%) were in CR, whereas 6 exhibited detectable disease. Conditioning regimens were mostly myelo-ablative (n=31). With a median follow-up of 6 years, 5-year overall and event-free survival rates were 70% (SE=8%) and 58% (SE=9%), respectively. The 5-year cumulative incidence of relapse and treatment-related mortality was 18% (SE=7%) and 24% (SE=8%), respectively. Six patients had relapsed (median time, 141 days (35-235)). A durable CR had been obtained in 4/6 patients after injection of donor lymphocytes (n=1) or vinblastine-corticosteroid therapy (n=3). Ten patients had died, eight due to transplant toxicity and two due to progressive disease. Allo-SCT is an efficient treatment for pediatric patients with high-risk relapsed ALK+ ALCL. However, the overall morbidity of allo-SCT raises questions about its place, given the efficacy of targeted agents currently under development in this disease.

Juvenile myelomonocytic leukemias (JMML) are rare but severe myelodysplastic and myeloproliferative neoplasms of infancy. They represent about 10 new cases per year in France and preferentially affect males. JMML are all stem cell diseases the common denominator of which is RAS pathway dysregulation, due to mutations in RAS (NRAS, KRAS) or RAS regulatory components (PTPN11, NF1 or CBL). This leads to an hypersensivity of myeloid progenitors to GM-CSF (granulo-macrophagic colony stimulating factor) which induces in turn excessive monocytic and macrophagic proliferation in blood and bone marrow. All organs can be infiltrated by this monocytic proliferation leading to multisystemic failure. Blast crisis with transformation into acute myeloid leukemia occurs in one third of patients. A salient feature of JMML is their frequent association with predisposition syndromes such as Noonan syndrome, neurofibromatosis and CBL syndrome, which are developmental diseases associated with a constitutional RAS pathway deregulation, now grouped under the name RASopathies. Clinical heterogeneity makes JMML diagnosis difficult. Splenomagaly is the most constant sign. Palor, adenopathy, respiratory or cutaneous symptoms can also be present. Blood smear shows monocytosis (1×10(9)/L) presence of myeloid progenitors and abnormal basophils. The demonstration of an endogeneous in vitro growth of myeloid progenitors although not very specific can help JMML diagnosis. Nowadays, genetic typing has to be included in the workup of JMML diagnosis and allows to evidence a mutation in more than 90% of cases. JMML have a poor prognosis. The only curative treatment is bone marrow transplantation but approximately 35% of patients relapse. JMML clinical course is highly heterogeneous and unpredictable. Some rare patients have an indolent evolution or even spontaneous remission. Age over two years, thrombopenia below 33×10(9)/L and high foetal hemoglobin (HbF) level for age are poor prognosis criteria but hardly predict individual outcome. Several research directions are currently being explored to improve prognosis prediction and provide more effective targeted treatments.

Item does not contain fulltext RASopathies, a family of disorders characterized by cardiac defects, defective growth, facial dysmorphism, variable cognitive deficits and predisposition to certain malignancies, are caused by constitutional dysregulation of RAS signalling predominantly through the RAF/MEK/ERK (MAPK) cascade. We report on two germline mutations (p.Gly39dup and p.Val55Met) in RRAS, a gene encoding a small monomeric GTPase controlling cell adhesion, spreading and migration, underlying a rare (2 subjects among 504 individuals analysed) and variable phenotype with features partially overlapping Noonan syndrome, the most common RASopathy. We also identified somatic RRAS mutations (p.Gly39dup and p.Gln87Leu) in 2 of 110 cases of non-syndromic juvenile myelomonocytic leukaemia, a childhood myeloproliferative/myelodysplastic disease caused by upregulated RAS signalling, defining an atypical form of this haematological disorder rapidly progressing to acute myeloid leukaemia. Two of the three identified mutations affected known oncogenic hotspots of RAS genes and conferred variably enhanced RRAS function and stimulus-dependent MAPK activation. Expression of an RRAS mutant homolog in Caenorhabditis elegans enhanced RAS signalling and engendered protruding vulva, a phenotype previously linked to the RASopathy-causing SHOC2(S2G) mutant. Overall, these findings provide evidence of a functional link between RRAS and MAPK signalling and reveal an unpredicted role of enhanced RRAS function in human disease.

Background Immune thrombocytopenia (ITP) is a childhood disorder that is often life-altering for children and their parents. Health related quality of life (HRQL) has never been chronologically monitored in children with ITP. We initiated a prospective study to assess HRQL from diagnosis to six months and define factors that influence this outcome in children with ITP. Methods 73 children with acute ITP aged from 2 to 18 years were prospectively enrolled in the study. According to the presence of bleeding, they were or were not given a 4-day course of corticosteroid treatment. The PedsQL™ 4.0 Generic Core Scale was completed by children and parents upon their inclusion in the study and 6 months after diagnosis. Results Over the six month period, quality of life improved in terms of their global, physical and psychosocial well-being for 54.5%, 35.6% and 36.2% of patients respectively. This improvement is clinically relevant compared to scores at diagnosis, corresponding at least to a minimal clinically important difference (MCID). Factors such as sex, age, platelet count, bleeding scores, bone marrow aspiration and persistence of ITP at 6 months were not significantly associated with HRQL scores. However, preceding viral infection was identified to have an impact on HRQL. Conclusions This first longitudinal study assessing HRQL in children with ITP reveals a global improvement in PedSQL™ 4.0. However, these results should be considered with caution since our data also confirm that self-report HRQL scores are not influenced by any analyzed biologic or clinical parameters. Others tools, such as Kids’ ITP Tools, would probably be required to assess the HRQL of this population. Trial registration Trial registration clinical trials.gov Identifier: NCT00331357.

Summary This study aimed to describe the clinical features and outcome of anaplastic large cell lymphoma (ALCL) with leukaemic presentation in children. Among 267 patients included in the French paediatric ALCL database between 1989 and 2012, nine (3%) were described as having cytologically detectable circulating tumour cells. Clinical features combined fever (8/9), nodal and extra-nodal disease (9/9), including hepato-splenic (9/9) and lung involvement (7/9). The level of hyperleucocytosis ranged from 30 to 120 × 109/l, with 12–90% of tumour cells. Diagnosis relied on a lymph node biopsy, with a positive ALK+ antibody immunostain in all nine cases, a T-cell immunophenotype in 7/9 cases and CD3 positivity in 5/9 cases. A small cell component was present in 6/9 cases. Only four patients achieved a complete remission with first-line therapy and 3/4 relapsed. Four patients are alive with a median follow-up of 31 months, two of them after allogeneic haematopoietic stem cell transplantation (HSCT), and five patients died, two of them of disease. In conclusion, ALCL with leukaemic presentation is very unusual and should be considered as high-risk lymphoma requiring new therapeutic strategies. The respective role of new agents and allogeneic HSCT in first complete remission still has to be assessed.

This single-center retrospective study reported the outcome of 19 children treated with a reduced-intensity conditioning (RIC) regimen prior to allogeneic stem cell transplantation (allo-SCT), for hematologic malignancies (n = 17), bone marrow failure (n = 1), and neuroblastoma (n = 1). Children were ineligible for standard myeloablative conditioning because of severe comorbidities (n = 9), a previous auto or allo-SCT (n = 7) or a prior history of extensive chemotherapy (n = 3). All patients underwent a fludarabine-based RIC regimen, and received grafts from matched-related donors (n = 5), match-unrelated donors (n = 6), or unrelated cord blood (UCB, n = 8). In this series, two patients treated with UCB failed to engraft and 63% achieved full donor chimerism at day 100 after allo-SCT. With a median follow-up of 537 d (range, 115-4136), treatment-related mortality was 16% and overall survival was 47%. The principal cause of death was disease relapse (n = 7). Acute graft versus host disease (GVHD) occurred in 53% of patients, while only 10% developed extensive chronic GVHD. Overall, results from this series suggest that RIC allo-SCT can be a valid alternative treatment option in unfit children with malignant hematological diseases. Prospective studies are needed to enlarge pediatric experience in this domain and better identify those children more suitable for a RIC allo-SCT approach.

Background: Gemtuzumab Ozogamicin (GO) is a humanized anti-CD33 monoclonal antibody linked to calicheamicin. It was developed to treat relapsed CD33+ AML patients, first at the dose of 9 mg/m² administered twice at day +1 and +14, than combined with chemotherapy but with reduced dose to lower toxicity. In 2008, we reported a 63% (50% of complete remission (CR) + 13% of CR with incomplete platelets recovery (CRp), platelets Materials and Method: This was a single center retrospective study including all CD33+ relapsed/refractory AML patients who received the MIDAM regimen, from 2008 to March 2015. Between 2008 and July 2012, all patients received GO as a single dose at 9 mg/m² day +4 (s-MIDAM group) and after until March 2015 it was decided to fractionate the GO dose according to Castaigne'schedule at 3 mg/m²/day day +1 +4 and +7 (fra-MIDAM group). All patients were treated as part of a compassionate use program as GO is not available in France for routine use. The main objective was to compare the incidence of SOS and related-deaths between both groups (s-MIDAM vs fra-MIDAM). Secondary objectives were to compare ORR (CR+CRp), median time of neutrophils and platelets (>20 Giga/L, >50 Giga/L, >100 Giga/L) recovery and overall survival (OS). Results: 33 patients were included in the study, 15 in the fra-MIDAM group and 18 in the s-MIDAM group. Characteristics of patients were similar between the former and the latter in terms of age (median: 55 vs 52 years, p=NS), gender (male: 60% vs 66%, p=NS), cytogenetics risk (favorable 33% vs 28%, intermediate 60% vs 39%, high: 7% vs 33%, p=NS) or median CD33+ expression (99% vs 99.5%, p=NS).There were more refractory patients in the s-MIDAM group (39% vs 7%, p=0.04) but more patients for whom adapted lower dose of Ara-C (4 g/m² instead of 10 g/m² total dose, for one patient) or mitoxantrone (3 patients did not received any, and 1 received 2 days instead of 3 days) were prescribed in the fra-MIDAM group (27% vs 0%, p=0.04). Also, 20% and 28% of patients received a reduced dose of GO (6 mg/m², administered in 2 fractionated dose (3 mg/m² twice) or a single dose) in the fra-MIDAM and the s-MIDAM groups, respectively (p=NS). ORR was similar between both groups (fra-MIDAM: 53% vs s-MIDAM: 61%, p=NS) as well as the CR rate (33% vs 39%, p=NS) or the CRp rate (20% vs 22%, p=NS). Median time to neutrophils and platelets (>20 Giga/L, >50 Giga/L and >100 Giga/L) recovery were also similar (fra-MIDAM: 29 days vs s-MIDAM: 26 days, p=0.25; 24 vs 26 days, p=NS; 27 vs 34 days, p=0.13 and 38 vs 36.5 days, p=NS). Among patients in response, 40% vs 67% were allotransplanted after the fra-MIDAM and the s-MIDAM regimens, respectively, (p=NS). With a median follow-up of 139 days and 782 days for the fra-MIDAM and the s-MIDAM groups, respectively, median OS was 7.2 months for the former and 10.2 months for the latter (p=NS). Sixty percent of patients died in the fra-MIDAM group vs 72% in the s-MIDAM group (p=NS), with no significant differences in terms of causes of death. Regarding our primary objective, 2 and 3 cases developed SOS after the fra-MIDAM and the s-MIDAM regimen, respectively, and these 5 patients died of SOS. Conclusion: Use of fractionated GO doses compared to single GO dose as part of the MIDAM salvage regimen for relapsed/refractory AML patients showed no advantages in terms of outcomes or lower toxicity, especially regarding incidence of SOS or death due to SOS. Both schedules are equivalent and can be used. Disclosures Mohty: Janssen: Honoraria; Celgene: Honoraria. Moreau:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees.

The efficacy of induction chemotherapy in childhood acute lymphoblastic leukemia (ALL) is usually evaluated on day 35. However, at this stage, many patients have already begun to recover and present with a regenerative bone marrow (BM) where hematogones may make the identification of residual blast cells problematic both in morphology and in flow cytometry (FCM). In the FRALLE (French Acute Lymphoblastic Leukemia) trials, evaluation is proposed on days 8, 21 and 35. Here we evaluated whether FCM performed on day 21 (D21), when hematogones are still absent, would prove informative. The cohort reported here was constituted of 45 children aged between 1 and 20 years old (median 6) treated for ALL according to the FRALLE recommendations since 2006. There were 81% B-ALL, 17% T-ALL and 2% of mixed phenotype acute leukemia (MPAL, T/My). At diagnosis, the mean percentage of BM blasts was 50%. Classification according to the European Group for Immunophenotyping of Leukemia (EGIL) was 3 B-I, 21 B-II, 11 B-III, 2 B-IV and 1 T-I, 2 T-II and 4 T-III. Extensive immunophenotyping at diagnosis identified a median of 3 leukemia associated immunophenotypes (LAIP, range 1-5), defined as discriminant from hematogones. Corticosensitivity was defined on a complete blood count (CBC) as less than 1 G/L of blast cells on day 8. Chemosensitivity was assessed on a bone marrow aspiration at day 21, both morphologically (< 5% blasts) and in FCM (MRD0). Molecular biology (according to Biomed2) was performed on BM samples collected on days 35 (MRD1) and 70 (MRD2). Follow-up median time was 59 months (3-276). Corticosensitivity was observed for 39/43 patients (one had received corticosteroids for a tonsillitis before being referred and diagnosed with ALL and another one had less than 1 G/L of blasts at diagnosis). Five/44 patients were identified as chemoresistant by morphology on D21 (one aplastic sample). Enough cells were available for minimal residual disease (MRD) by FCM in 43 patients, on bone marrow collected on EDTA. As a mean, 586 328 total nucleated cells were acquired in FCM (range 9 616 - 1 751 000) thereby providing good sensitivity. Multiparameter FCM in 6 to 8 colors was performed on a single tube, customized according to each patient’s LAIP. Five MRD thresholds were defined as follows : level 1, >10-2 detected blasts; level 2, 10-3- Event-free survival (EFS; Kaplan Meier Log rank test) was statistically significant (p=0.023) when comparing patients with level 4 or 5 MRD to the others. Level 3 patients had an intermediate EFS and OS. In an independent cohort of 79 patients with evaluable FMC MRD on day 21 from a different center, the same good prognosis value of MRD lower than 10-4at that time point was confirmed for EFS (p=0.03). Childhood ALL has become of relatively good prognosis with the progress in therapies. However, it is noteworthy that half the patients had detectable MRD at levels 1, 2 or 3, which probably prompted the clinicians to intensify treatment. However, below level 3, i.e. In summary, this work demonstrates the feasibility of FCM evaluation on D21, with the advantage of not being complicated by the presence of hematogones. Moreover, interpretation remains delicate in morphology at this time point where BM smears may be very poor. FCM thereby provides precious early information on chemosensitivity with a single patient-adapted antibody combination. Disclosures No relevant conflicts of interest to declare.