Autoimmune cytopenia and Kabuki syndrome in paediatrics: Insights in 11 patients.

Kabuki syndrome (KS) is now listed in the Human Inborn Errors of Immunity (IEI) Classification. It is a rare disease caused by KMT2D and KDM6A variants, dominated by intellectual disability and characteristic facial features. Recurrently, pathogenic variants are identified in those genes in patients examined for autoimmune cytopenia (AIC), but interpretation remains challenging. This study aims to describe the genetic diagnosis and the clinical management of patients with paediatric-onset AIC and KS. Among 11 patients with AIC and KS, all had chronic immune thrombocytopenic purpura, and seven had Evans syndrome. All had other associated immunopathological manifestations, mainly symptomatic hypogammaglobinaemia. They had a median of 8 (5-10) KS-associated manifestations. Pathogenic variants were detected in KMT2D gene without clustering, during the immunological work-up of AIC in three cases, and the clinical strategy to validate them is emphasized. Eight patients received second-line treatments, mainly rituximab and mycophenolate mofetil. With a median follow-up of 17 (2-31) years, 8/10 alive patients still needed treatment for AIC. First-line paediatricians should be able to recognize and confirm KS in children with ITP or multiple AIC, to provide early appropriate clinical management and specific long-term follow-up. The epigenetic immune dysregulation in KS opens exciting new perspectives.

Pubertal development of transfusion-dependent thalassemia patients in the era of oral chelation with deferasirox: results from the French registry.

Not available.

Next generation sequencing (NGS) interest in deciphering erythrocyte molecular defects' association in red cell disorders: Clinical and erythrocyte phenotypes of patients with mutations inheritance in PIEZO1, Spectrin ß1, RhAG and SLC4A1.

We report here an instructive case referred at 16 months-old for exploration of hemolysis without anemia (compensated anemia with reticulocytosis). The biology tests confirmed the hemolysis with increased total and indirect bilirubin. The usual hemolysis diagnosis tests were normal (DAT, G6PD, PK, Hb electrophoresis) except cytology and ektacytometry suggesting an association of multiple red blood cell (RBC) membrane disorders. This led us to propose a molecular screening analysis using targeted-Next Generation Sequencing (t-NGS) with a capture technique on 93 genes involved in RBC and erythropoiesis defects. We identified 4 missense heterozygous allelic variations, all of them were described without any significance (VUS) in the SLC4A1, RhAG, PIEZO1 and SPTB genes. The study of the familial cosegregation and research functional tests allowed to decipher the role of at least two by two genes in the phenotype and the hemolytic disease of this young patient. Specialized t-NGS panel (or virtual exome/genome sequencing) in a disease-referent laboratory and the motivated collaboration of clinicians, biologists and scientists should be the gold standard for improving the diagnosis of the patients affected with RBC diseases or rare inherited anemias.

Molecular and clinicopathologic characterization of pediatric histiocytoses.

The spectrum of somatic mutations in pediatric histiocytoses and their clinical implications are not fully characterized, especially for non-Langerhans cell histiocytosis (-LCH) subtypes. A cohort of 415 children with histiocytosis from the French histiocytosis registry was reviewed and analyzed for BRAFV600E . Most BRAFWT samples were analyzed by next-generation sequencing (NGS) with a custom panel of genes for histiocytosis and myeloid neoplasia. Of 415 case samples, there were 366 LCH, 1 Erdheim-Chester disease, 21 Rosai-Dorfman disease (RDD), 21 juvenile xanthogranuloma (JXG, mostly with severe presentation), and 6 malignant histiocytosis (MH). BRAFV600E was the most common mutation found in LCH (50.3%, n = 184). Among 105 non-BRAFV600E -mutated LCH case samples, NGS revealed mutations as follows: MAP2K1 (n = 44), BRAF exon 12 deletions (n = 26), and duplications (n = 8), other BRAF V600 codon mutation (n = 4), and non-MAP-kinase pathway genes (n = 5). Wild-type sequences were identified in 17.1% of samples. BRAFV600E was the only variant significantly correlated with critical presentations: organ-risk involvement and neurodegeneration. MAP-kinase pathway mutations were identified in seven RDD (mostly MAP2K1) and three JXG samples, but most samples were wild-type on NGS. Finally, two MH samples had KRAS mutations, and one had a novel BRAFG469R mutation. Rarely, we identified mutations unrelated to MAP-kinase pathway genes. In conclusion, we characterized the mutational spectrum of childhood LCH and clinical correlations of variants and subtypes. Variants responsible for JXG and RDD were not elucidated in more than half of the cases, calling for other sequencing approaches.

Epstein-Barr Virus in Childhood and Adolescent Classic Hodgkin Lymphoma in a French Cohort of 301 Patients.

OBJECTIVE: The aim was to analyze the role of Epstein-Barr virus (EBV) in the bioclinical characteristics of patients treated for classic Hodgkin lymphoma (cHL) in France. METHODS: Biopathologic data of 301 patients treated for a cHL in/or according to the EuroNet PHL-C1 trial between November 2008 and February 2013 were centrally reviewed. RESULTS: Median age at diagnosis was 14 (3 to 18) years and the F/M ratio 0.86, 0.47 before 10 years and 0.9 from 11 to 18. CHL subtypes were nodular sclerosis for 266/301 (88%) patients, mixed cellularity for 22/301 (7%), lymphocyte rich for 2/301 (1%), and 11/301 were unclassified. EBV positivity by in situ hybridization was observed for 68/301 (23%) patients, significantly associated with mixed cellularity subtype and male sex, particularly overrepresented in boys below 10 years: 15/23 (65%) versus 28/139 among other male patients (20%). EBV viral load was detectable in 22 of 108 (22%) tested cases and was overrepresented in EBV cHL (13/28) versus non-EBV cHL (9/80) patients. Detailed semiquantitative histologic analysis showed a high number of B-cell residual follicles in EBV cHL relative to EBV-negative HL. CONCLUSION: Distribution of EBV cHL in children and adolescents is associated with young age and male sex, suggesting a specific physiopathology and may require a differential therapeutic approach.

Should treatment of ALK-positive anaplastic large cell lymphoma be stratified according to minimal residual disease?

In anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALK+ ALCL), positive minimal residual disease (MRD+) after the first chemotherapy course was proven of strong prognostic significance. We aimed to validate these results in 138 French patients. Eighty-seven patients had a detectable minimal disseminated disease at diagnosis (MDD+). Early MRD assessment was performed in 33 of 87 patients and was positive in 18 and negative in 15 (MRD-). Three-year progression-free survival was significantly correlated with the MDD/MRD status: 81.1% in MDD-, 69.6% in MDD+/MRD-, and 15.2% in MDD+/MRD+ patients. In conclusion, we confirmed on an independent cohort that the MDD/MRD status has strong prognosis significance in ALK+ ALCL.

Maternal exposure to pesticides and risk of childhood lymphoma in France: A pooled analysis of the ESCALE and ESTELLE studies (SFCE).

BACKGROUND: Few studies have assessed the relation between maternal prenatal pesticides use and childhood lymphoma risk, some reporting a positive association with non-Hodgkin lymphoma (NHL). We investigated the association between maternal exposure to pesticides during pregnancy and childhood Hodgkin (HL) and non-Hodgkin lymphoma. METHODS: We pooled data from the two French national population-based case-control studies ESCALE (2003-2004) and ESTELLE (2010-2011). Data on domestic and occupational exposures to pesticides during pregnancy were obtained through standardised maternal interviews. Logistic regression models were used to compute odds ratios (OR) and 95% confidence intervals (CI) for HL and NHL, by pesticide category adjusted for potential confounders. Analyses by histological subtypes were also performed. RESULTS: We included 328 H L, 305 non-Hodgkin NHL and 2,415 controls. Around 40% of control mothers reported having used pesticides during index pregnancy, of whom 95% reported insecticides use. Maternal use of herbicides and fungicides occurred mostly in combination with insecticides. Insecticides use was more frequently reported in cases than controls (ORNHL = 1.6 [95%CI 1.3-2.1], p = 0.0001; ORHL = 1.3 [95%CI 1.0-1.7], p = 0.03). This association appeared more marked for Burkitt lymphoma and mixed cellularity classical HL. No obvious association was observed with occupational pesticides exposure during pregnancy. CONCLUSION: These results suggest that maternal domestic use of insecticides during pregnancy might be related to both childhood NHL and HL. Further larger studies are urgently needed.

Childhood Langerhans cell histiocytosis with severe lung involvement: a nationwide cohort study.

BACKGROUND: Lung involvement in childhood Langerhans cell histiocytosis (LCH) is infrequent and rarely life threatening, but occasionally, severe presentations are observed. METHODS: Among 1482 children (< 15 years) registered in the French LCH registry (1994-2018), 111 (7.4%) had lung involvement. This retrospective study included data for 17 (1.1%) patients that required one or more intensive care unit (ICU) admissions for respiratory failure. RESULTS: The median age was 1.3 years at the first ICU hospitalization. Of the 17 patients, 14 presented with lung involvement at the LCH diagnosis, and 7 patients (41%) had concomitant involvement of risk-organ (hematologic, spleen, or liver). Thirty-five ICU hospitalizations were analysed. Among these, 22 (63%) were secondary to a pneumothorax, 5 (14%) were associated with important cystic lesions without pneumothorax, and 8 (23%) included a diffuse micronodular lung infiltration in the context of multisystem disease. First-line vinblastine-corticosteroid combination therapy was administered to 16 patients; 12 patients required a second-line therapy (cladribine: n = 7; etoposide-aracytine: n = 3; targeted therapy n = 2). A total of 6 children (35%) died (repeated pneumothorax: n = 3; diffuse micronodular lung infiltration in the context of multisystem disease: n = 2; following lung transplantation: n = 1). For survivors, the median follow-up after ICU was 11.2 years. Among these, 9 patients remain asymptomatic despite abnormal chest imaging. CONCLUSIONS: Severe lung involvement is unusual in childhood LCH, but it is associated with high mortality. Treatment guidelines should be improved for this group of patients: viral infection prophylaxis and early administration of a new LCH therapy, such as targeted therapy.

De novo missense variants in the RAP1B gene identified in two patients with syndromic thrombocytopenia.

We present two independent cases of syndromic thrombocytopenia with multiple malformations, microcephaly, learning difficulties, dysmorphism and other features. Exome sequencing identified two novel de novo heterozygous variants in these patients, c.35G>T p.(Gly12Val) and c.178G>C p.(Gly60Arg), in the RAP1B gene (NM_001010942.2). These variants have not been described previously as germline variants, however functional studies in literature strongly suggest a clinical implication of these two activating hot spot positions. We hypothesize that pathogenic missense variants in the RAP1B gene cause congenital syndromic thrombocytopenia with a spectrum of associated malformations and dysmorphism, possibly through a gain of function mechanism.

Long-term follow-up of children with risk organ-negative Langerhans cell histiocytosis after 2-chlorodeoxyadenosine treatment.

The nucleoside analogue, 2-chlorodeoxyadenosine (2CDA), was reported to be an active treatment for childhood Langerhans cell histiocytosis (LCH) without risk organ (RO-) involvement. However, we lack data on long-term effects of 2CDA treatment, including the disease reactivation rate, permanent sequelae and long-term tolerance. This study included 44 children from the French LCH registry, treated for a RO- LCH with 2CDA monotherapy (median number of six courses). The median age at the beginning of 2CDA was 3·6 years (range, 0·3-19·7 years) and the median follow-up after was 5·4 years (range, 0·6-15·1 years). Objective response to 2CDA was observed in 25 patients (56·8%), while six patients (13·6%) had stable disease and 13 patients (29·5%) exhibited progressive disease. Among patients without progression, only two experienced disease reactivation after 2CDA discontinuation. The five-year cumulative incidence of disease progression or reactivation after 2CDA therapy initiation was 34·3%. The lymphopenia reported in all cases [72% below absolute lymphocyte count (ALC) of 0·5 G/l], was addressed with appropriate prophylactic measures. Other toxicities above grade 2 were uncommon, and no second malignant neoplasm or neuropathy was reported. The five-year overall survival was 97·7%. In conclusion, we could confirm that 2CDA monotherapy was a beneficial long-term therapy for treating patients with RO- LCH. Appropriate management of induced immune deficiency is mandatory.

IL10RA modulates crizotinib sensitivity in NPM1-ALK+ anaplastic large cell lymphoma.

Anaplastic large cell lymphoma (ALCL) is a T-cell malignancy predominantly driven by a hyperactive anaplastic lymphoma kinase (ALK) fusion protein. ALK inhibitors, such as crizotinib, provide alternatives to standard chemotherapy with reduced toxicity and side effects. Children with lymphomas driven by nucleophosmin 1 (NPM1)-ALK fusion proteins achieved an objective response rate to ALK inhibition therapy of 54% to 90% in clinical trials; however, a subset of patients progressed within the first 3 months of treatment. The mechanism for the development of ALK inhibitor resistance is unknown. Through genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) activation and knockout screens in ALCL cell lines, combined with RNA sequencing data derived from ALK inhibitor-relapsed patient tumors, we show that resistance to ALK inhibition by crizotinib in ALCL can be driven by aberrant upregulation of interleukin 10 receptor subunit alpha (IL10RA). Elevated IL10RA expression rewires the STAT3 signaling pathway, bypassing otherwise critical phosphorylation by NPM1-ALK. IL-10RA expression does not correlate with response to standard chemotherapy in pediatric patients, suggesting that a combination of crizotinib and chemotherapy could prevent ALK inhibitor resistance-specific relapse.

Childhood pulmonary Langerhans cell histiocytosis: a comprehensive clinical-histopathological and BRAFV600E mutation study from the French national cohort.

Childhood pulmonary Langerhans cell histiocytosis (PLCH) is a rare disease. Its pulmonary histopathology, according to comprehensive clinical-radiological findings and BRAFV600E mutation status, has not yet been thoroughly documented. From the 167 childhood PLCH cases entered in the French National Histiocytosis Registry (1983-2016), we retrieved lung biopsies from a consecutive retrospective series of 17 patients, diagnosed when they were 2 weeks to 16 years old (median, 9.4 years), and report the clinical and histopathological findings herein. Histological analyses of biopsies (16 surgical and 1 postmortem) found the following features, alone or associated: Langerhans cell (LC) nodules with cavitation (9/17), cysts (14/17), fibrotic scars (2/17), peribronchiolar topographic distribution of the lesions (10/17), and accessory changes, like stretch emphysema (7/17). Those characteristics closely resemble those describing adult PLCH. However, unusual findings observed were 2 large nodules and a diffuse interstitial LC infiltrate. BRAFV600E mutation was detected in 4 of 12 samples tested, notably in the 3 with unusual features. In conclusion, childhood PLCH mostly shares the common histology features already described in adult PLCH, regardless of age. Because smoking is considered the major trigger in PLCH pathogenesis, the findings based on this series suggest other inducers of bronchiolar LC recruitment, especially in very young patients.

Incidence and risk factors for clinical neurodegenerative Langerhans cell histiocytosis: a longitudinal cohort study.

Neurodegenerative (ND) complications in Langerhans cell histiocytosis (LCH) are a late-onset but dramatic sequelae for which incidence and risk factors are not well defined. Based on a national prospective registry of paediatric LCH patients, we determined the incidence rate of clinical ND LCH (cND-LCH) and analysed risk factors, taking into account disease extent and molecular characteristics. Among 1897 LCH patients, 36 (1·9%) were diagnosed with a cND-LCH. The 10-year cumulative incidence of cND-LCH was 4·1%. cND-LCH typically affected patients previously treated for a multisystem, risk organ-negative LCH, represented in 69·4% of cND-LCH cases. Pituitary gland, skin and base skull/orbit bone lesions were more frequent (P < 0·001) in cND-LCH patients compared to those without cND-LCH (respectively 86·1% vs. 12·2%, 75·0% vs. 34·2%, and 63·9% vs. 28·4%). The 'cND susceptible patients' (n = 671) i.e., children who had experienced LCH disease with pituitary or skull base or orbit bone involvement, had a 10-year cND risk of 7·8% vs. 0% for patients who did not meet these criteria. Finally, BRAFV600E status added important information among these cND susceptible patients, with the 10-year cND risk of 33·1% if a BRAFV600E mutation was present compared to 2·9% if it was absent (P = 0·002).

Late effects after hematopoietic stem cell transplantation for ß-thalassemia major: the French national experience.

In this retrospective study, we evaluate long-term complications in nearly all ß-thalassemia-major patients who successfully received allogeneic hematopoietic stem cell transplantation in France. Ninety-nine patients were analyzed with a median age of 5.9 years at transplantation. The median duration of clinical follow up was 12 years. All conditioning regimens were myeloablative, most were based on busulfan combined with cyclophosphamide, and more than 90% of patients underwent a transplant from a matched sibling donor. After transplantation, 11% of patients developed thyroid dysfunction, 5% diabetes, and 2% heart failure. Hypogonadism was present in 56% of females and 14% of males. Female patients who went on to normal puberty after transplant were significantly younger at transplantation than those who experienced delayed puberty (median age 2.5 vs 8.7 years). Fertility was preserved in 9 of 27 females aged 20 years or older and 2 other patients became pregnant following oocyte donation. In addition to patient's age and higher serum ferritin levels at transplantation, time elapsed since transplant was significantly associated with decreased height growth in multivariate analysis. Weight growth increased after transplantation particularly in females, 36% of adults being overweight at last evaluation. A comprehensive long-term monitoring, especially of endocrine late effects, is required after hematopoietic stem cell transplantation for thalassemia.

Advanced stage nodular lymphocyte predominant Hodgkin lymphoma in children and adolescents: clinical characteristics and treatment outcome - a report from the SFCE & CCLG groups.

Advanced stage nodular lymphocyte predominant Hodgkin lymphoma (nLPHL) is extremely rare in children and as a consequence, optimal treatment for this group of patients has not been established. Here we retrospectively evaluated the treatments and treatment outcomes of 41 of our patients from the UK and France with advanced stage nLPHL. Most patients received chemotherapy, some with the addition of the anti CD20 antibody rituximab or radiotherapy. Chemotherapy regimens were diverse and followed either classical Hodgkin lymphoma or B non-Hodgkin lymphoma protocols. All 41 patients achieved a complete remission with first line treatment and 40 patients are alive and well in remission. Eight patients subsequently relapsed and 1 patient died of secondary cancer (9 progression-free survival events). The median time to progression for those who progressed was 21 months (5·9-73·8). The median time since last diagnosis is 87·3 months (8·44-179·20). Thirty-six (90%), 30 (75%) and 27 (68%) patients have been in remission for more than 12, 24 and 36 months, respectively. Overall, the use of rituximab combined with multi-agent chemotherapy as first line treatment seems to be a reasonable therapeutic option.

BRAF Mutation Correlates With High-Risk Langerhans Cell Histiocytosis and Increased Resistance to First-Line Therapy.

PURPOSE: Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasia with a broad spectrum of clinical manifestations and outcomes in children. The somatic BRAF(V600E) mutation occurs frequently, but clinical significance remains to be determined. PATIENTS AND METHODS: BRAF(V600E) mutation was investigated in a French LCH cohort. We analyzed associations between mutation status and clinical presentation, extent of disease, reactivation rate, response to therapy, and long-term permanent sequelae. RESULTS: Among 315 patients with successfully determined BRAF status, 173 (54.6%) carried a BRAF(V600E) mutation. Patients with BRAF(V600E) manifested more severe disease than did those with wild-type BRAF. Patients with BRAF(V600E) comprised 87.8% of patients (43 of 49) with multisystem LCH with risk organ involvement (liver, spleen, hematology), 68.6% of patients (35 of 51) with multisystem LCH without risk organ involvement, 43.9% of patients (86 of 196) with single-system LCH, and 42.1% of patients (8 of 19) with lung-involved LCH (P < .001). BRAF(V600E) mutation was also associated with organ involvement that could lead to permanent, irreversible damage, such as neurologic (75%) and pituitary (72.9%) injuries. Compared with patients with wild-type BRAF, patients with BRAF(V600E) more commonly displayed resistance to combined vinblastine and corticosteroid therapy (21.9% v 3.3%; P = .001), showed a higher reactivation rate (5-year reactivation rate, 42.8% v 28.1%; P = .006), and had more permanent, long-term consequences from disease or treatment (27.9% v 12.6%; P = .001). CONCLUSION: In children with LCH, BRAF(V600E) mutation was associated with high-risk features, permanent injury, and poor short-term response to chemotherapy. Further population-based studies should be undertaken to confirm our observations and to assess the impact of BRAF inhibitors for this subgroup of patients who may benefit from targeted therapy.

Langerhans cell histiocytosis: therapeutic strategy and outcome in a 30-year nationwide cohort of 1478 patients under 18 years of age.

The French national cohort of children with Langerhans cell histiocytosis (LCH) has included 1478 patients since it was established in 1983. LCH therapeutic strategies substantially changed in 1998, so we have divided the cohort into two 15-year periods. Starting in 1998, therapy duration increased from 6 to 12 months, repeated induction therapy was performed in cases showing a poor response to the first induction with vinblastine and steroids, and refractory disease in a risk organ (RO+) was treated with cladribine and cytarabine. A total of 483 (33%) patients were enrolled before 1998, and 995 (67%) after 1998. Five-year survival was 96·6% (95% confidence interval: 95·4-97·5%) overall, improving from 92% pre-1998 to 99% post-1998 (P < 0·001 adjusted to disease extent). This change was supported by an increase in 5-year survival from 60% to 92% in the RO+ group. Survival was particularly associated with cladribine and cytarabine among refractory RO+ patients. Disease reactivation was slightly less frequent after 1998, due to better enrolment of single-system patients, extended therapy duration, and more efficient second-line therapy. The crude rates of endocrine and neurological sequelae (the most frequent sequelae) appeared to improve over time, but this difference was not observed when the analysis was stratified by disease extent.