RESUMEN
Langerhans cell histiocytosis (LCH) is a myeloid neoplastic disorder characterized by lesions with CD1a-positive/Langerin (CD207)-positive histiocytes and inflammatory infiltrate that can cause local tissue damage and systemic inflammation. Clinical presentations range from single lesions with minimal impact to life-threatening disseminated disease. Therapy for systemic LCH has been established through serial trials empirically testing different chemotherapy agents and durations of therapy. However, fewer than 50% of patients who have disseminated disease are cured with the current standard-of-care vinblastine/prednisone/(mercaptopurine), and treatment failure is associated with long-term morbidity, including the risk of LCH-associated neurodegeneration. Historically, the nature of LCH-whether a reactive condition versus a neoplastic/malignant condition-was uncertain. Over the past 15 years, seminal discoveries have broadly defined LCH pathogenesis; specifically, activating mitogen-activated protein kinase pathway mutations (most frequently, BRAFV600E) in myeloid precursors drive lesion formation. LCH therefore is a clonal neoplastic disorder, although secondary inflammatory features contribute to the disease. These paradigm-changing insights offer a promise of rational cures for patients based on individual mutations, clonal reservoirs, and extent of disease. However, the pace of clinical trial development behind lags the kinetics of translational discovery. In this review, the authors discuss the current understanding of LCH biology, clinical characteristics, therapeutic strategies, and opportunities to improve outcomes for every patient through coordinated agent prioritization and clinical trial efforts.
Asunto(s)
Histiocitosis de Células de Langerhans , Humanos , Histiocitosis de Células de Langerhans/tratamiento farmacológicoRESUMEN
The prognostic impact of PICALM::MLLT10 status in childhood leukaemia is not well described. Ten International Berlin Frankfurt Münster-affiliated study groups and the Children's Oncology Group collaborated in this multicentre retrospective study. The presence of the PICALM::MLLT10 fusion gene was confirmed by fluorescence in situ hybridization and/or RNA sequencing at participating sites. Ninety-eight children met the study criteria. T-cell acute lymphoblastic leukaemia (T-ALL) and acute myeloid leukaemia (AML) predominated 55 (56%) and 39 (40%) patients, respectively. Most patients received a chemotherapy regimen per their disease phenotype: 58% received an ALL regimen, 40% an AML regimen and 1% a hybrid regimen. Outcomes for children with PICALM::MLLT10 ALL were reasonable: 5-year event-free survival (EFS) 67% and 5-year overall survival (OS) 76%, but children with PICALM::MLLT10 AML had poor outcomes: 5-year EFS 22% and 5-year OS 26%. Haematopoietic stem cell transplant (HSCT) did not result in a significant improvement in outcomes for PICALM::MLLT10 AML: 5-year EFS 20% for those who received HSCT versus 23% for those who did not (p = 0.6) and 5-year OS 37% versus 36% (p = 0.7). In summary, this study confirms that PICALM::MLLT10 AML is associated with a dismal prognosis and patients cannot be salvaged with HSCT; exploration of novel therapeutic options is warranted.
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Leucemia Mieloide Aguda , Proteínas de Ensamble de Clatrina Monoméricas , Niño , Humanos , Hibridación Fluorescente in Situ , Estudios Retrospectivos , Proteínas de Fusión Oncogénica/genética , Resultado del Tratamiento , Leucemia Mieloide Aguda/genética , Factores de Transcripción/genética , Enfermedad Aguda , Pronóstico , Proteínas de Ensamble de Clatrina Monoméricas/genéticaRESUMEN
Over 50% of patients with systemic LCH are not cured with front-line therapies, and data to guide salvage options are limited. We describe 58 patients with LCH who were treated with clofarabine. Clofarabine monotherapy was active against LCH in this cohort, including heavily pretreated patients with a systemic objective response rate of 92.6%, higher in children (93.8%) than adults (83.3%). BRAFV600E+ variant allele frequency in peripheral blood is correlated with clinical responses. Prospective multicentre trials are warranted to determine optimal dosing, long-term efficacy, late toxicities, relative cost and patient-reported outcomes of clofarabine compared to alternative LCH salvage therapy strategies.
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Clofarabina , Histiocitosis de Células de Langerhans , Humanos , Clofarabina/uso terapéutico , Clofarabina/administración & dosificación , Histiocitosis de Células de Langerhans/tratamiento farmacológico , Masculino , Femenino , Adulto , Adolescente , Niño , Persona de Mediana Edad , Preescolar , Adulto Joven , Anciano , Recurrencia , Proteínas Proto-Oncogénicas B-raf/genética , Lactante , Resultado del Tratamiento , Terapia Recuperativa , Nucleótidos de Adenina/uso terapéutico , Nucleótidos de Adenina/administración & dosificación , Nucleótidos de Adenina/efectos adversos , Arabinonucleósidos/uso terapéutico , Arabinonucleósidos/administración & dosificación , Arabinonucleósidos/efectos adversosRESUMEN
Optimal therapeutic approaches for advanced Langerhans cell histiocytosis (LCH) are not known. We assessed the safety and efficacy of combined chemotherapy with MAPK pathway inhibition in 10 patients with refractory systemic disease and/or LCH-associated neurodegeneration. Overall response rate was 9/10 (90%) for the entire cohort: 5/5 (100%) for patients with systemic disease and 6/7 (86%) for patients with central nervous system disease. BRAFV600E+ peripheral blood fraction decreased in 5/6 (83%). Toxicities included fever, skin rash, myalgias, neuropathy, cytopenias and hypocalcaemia. Prospective trials are required to optimize combination strategies, determine potential to achieve cure and compare outcomes to chemotherapy or MAPK inhibitor monotherapy.
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Histiocitosis de Células de Langerhans , Sistema de Señalización de MAP Quinasas , Inhibidores de Proteínas Quinasas , Femenino , Humanos , Masculino , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Histiocitosis de Células de Langerhans/tratamiento farmacológico , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Inhibidores de Proteínas Quinasas/uso terapéutico , Inhibidores de Proteínas Quinasas/efectos adversos , Inhibidores de Proteínas Quinasas/administración & dosificación , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Proteínas Proto-Oncogénicas B-raf/genética , Recurrencia , Resultado del TratamientoRESUMEN
Here we report efficacy, pharmacokinetics, and safety data obtained in treatment-naive, pediatric patients with newly diagnosed advanced MDS receiving azacitidine in the AZA-JMML-001 study. The primary endpoint was response rate (proportion of patients with complete response [CR], partial response [PR], or marrow CR, sustained for ≥4 weeks). Of the 10 patients enrolled, one had an unconfirmed marrow CR and none had confirmed responses after three cycles; the study was therefore closed after stage 1. Azacitidine was well tolerated. The lack of efficacy of azacitidine in pediatric patients with newly diagnosed advanced MDS highlights the need for effective new treatments in these patients.
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Trasplante de Células Madre Hematopoyéticas , Leucemia Mieloide Aguda , Síndromes Mielodisplásicos , Humanos , Niño , Azacitidina/efectos adversos , Leucemia Mieloide Aguda/tratamiento farmacológico , Síndromes Mielodisplásicos/tratamiento farmacológico , Síndromes Mielodisplásicos/diagnóstico , Resultado del Tratamiento , Trasplante de Células Madre Hematopoyéticas/efectos adversosRESUMEN
ETV6 mutations are rare but recurrent somatic events in myeloid neoplasms and are negatively prognostic in myelodysplastic syndrome. We set out to examine the clinical and molecular characteristics of patients undergoing investigation for myeloid neoplasms, found to have deleterious ETV6 mutations. ETV6 mutations occurred in 33 of 5793 (0.6%) cases investigated and predominantly in high-risk disease entities including MDS with increased blasts, primary myelofibrosis and AML, myelodysplasia-related. In three cases, isolated iso (17q) karyotype was concurrently detected, an otherwise rare karyotype in myeloid neoplasms. ETV6 mutations were frequently subclonal and never occurred as an isolated abnormality with ASXL1 (n = 22, 75%), SRSF2 (n = 14, 42%) and SETBP1 (n = 11, 33%) the predominant co-mutations. Restricting to patients with MDS, higher rates of ASXL1, SETBP1, RUNX1 and U2AF1 mutations occurred in ETV6 mutated cases, relative to a consecutive control cohort with wild-type ETV6. The median OS of the cohort was 17.5 months. This report highlights the clinical and molecular associations of somatic ETV6 mutations in myeloid neoplasms, suggests their occurrence as a later event, and proposes further translational research questions for their role in myeloid neoplasia.
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Leucemia Mieloide Aguda , Síndromes Mielodisplásicos , Trastornos Mieloproliferativos , Neoplasias , Humanos , Leucemia Mieloide Aguda/genética , Mutación , Síndromes Mielodisplásicos/genética , Trastornos Mieloproliferativos/genética , Pronóstico , Proteína ETS de Variante de Translocación 6RESUMEN
Telomere dysfunctions are associated with several hematopoietic stem cell (HSC) malignancies. Recent findings have indicated that the occurrence of rare variants of unknown significance (VUS) in the Telomerase Reverse Transcriptase (TERT) gene influences the outcomes of patients with myelodysplastic syndromes undergoing allogeneic HSC transplantation. However, the role of TERT variants has been historically controversial as initially considered pathogenic variants (H412Y, A202T) presenting functional consequences, were found very frequent in general population questioning their pathogenicity and risk allele significance. Herein, we show that overall TERT VUS are non-recurrent in myeloid disorders and cannot be considered risk alleles individually nor can their biological impact.
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Leucemia Mieloide , Telomerasa , Células Madre Hematopoyéticas , Humanos , Leucemia Mieloide/genética , Telomerasa/genética , Telómero/metabolismoRESUMEN
Myelodysplastic syndromes (MDS) are characterized by variable clinical manifestations and outcomes. Several prognostic systems relying on clinical factors and cytogenetic abnormalities have been developed to help stratify MDS patients into different risk categories of distinct prognoses and therapeutic implications. The current abundance of molecular information poses the challenges of precisely defining patients' molecular profiles and their incorporation in clinically established diagnostic and prognostic schemes. Perhaps the prognostic power of the current systems can be boosted by incorporating molecular features. Machine learning (ML) algorithms can be helpful in developing more precise prognostication models that integrate complex genomic interactions at a higher dimensional level. These techniques can potentially generate automated diagnostic and prognostic models and assist in advancing personalized therapies. This review highlights the current prognostication models used in MDS while shedding light on the latest achievements in ML-based research.
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Síndromes Mielodisplásicos , Aberraciones Cromosómicas , Genómica/métodos , Humanos , Aprendizaje Automático , Síndromes Mielodisplásicos/diagnóstico , Síndromes Mielodisplásicos/genética , Síndromes Mielodisplásicos/terapiaRESUMEN
PURPOSE OF REVIEW: To review available data on the relationship of MDS and aging and to address the question if biological changes of (premature) aging are a prerequisite for the development of MDS. RECENT FINDINGS: Whereas the association of MDS with advanced age and some common biologic features of aging and MDS are well established, additional evidence for both, especially on the role of stem cells, the stem cell niche, and inflammation, has been recently described. Biologically, many but not all drivers of aging also play a role in the development and propagation of MDS and vice versa. As a consequence, aging contributes to the development of MDS which can be seen as an interplay of clonal disease and normal and premature aging. The impact of aging may be different in specific MDS subtypes and risk groups.
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Envejecimiento/metabolismo , Transformación Celular Neoplásica/metabolismo , Células Madre Hematopoyéticas/metabolismo , Síndromes Mielodisplásicos/metabolismo , Envejecimiento/patología , Transformación Celular Neoplásica/patología , Hematopoyesis , Células Madre Hematopoyéticas/patología , Humanos , Síndromes Mielodisplásicos/patologíaRESUMEN
Morphological features of eosinophils in patients with reactive eosinophilia (28 patients) and clonal eosinophilia (26 patients) have been compared with each other and with the eosinophil characteristics of healthy volunteers (three subjects) and of patients with the idiopathic hypereosinophilic syndrome (three patients). Morphological features, assessed in isolation from other haematological abnormalities, were found to have poor specificity for a myeloid neoplasm. The most useful feature was the presence of basophilic granules in mature eosinophils, which was associated particularly with acute myeloid leukaemia with inv(16). Marked reduction in granules occurred more often in some subsets of the myeloid neoplasm group but nevertheless was lacking in specificity since it was not infrequently seen in reactive eosinophilia. Although experienced morphologists more often considered that a myeloid neoplasm was likely in patients in whom this was the diagnosis (69%), myeloid neoplasia was also considered likely in a considerable proportion (39%) of patients with reactive eosinophilia. Morphological abnormalities of eosinophils therefore cannot be assessed in isolation in seeking to make a diagnosis of a myeloid neoplasm. Morphology is, however, needed and should be integrated with the results of other investigations.
RESUMEN
OBJECTIVE: Chronic lymphocytic leukemia (CLL) treatment has changed dramatically, and landscape of second hematologic malignancies (SHM) evolves in the new era of targeted therapy. No data were available about the real-world burden of SHM. METHODS: All 2631 patients with CLL in the Cancer registry of Norway registered 2003-2012 were included. RESULTS: After median follow-up of 6.6 years, 103 patients (4%) developed SHM. Diffuse large B-cell lymphoma (DLBCL) was most common (n = 65; 63%). Median survival was 9.3 years (95% CI; 8.9-9.8) in non-SHM patients and 1.7 years in DLBCL, 0.8 years in Hodgkin lymphoma (n = 12), and 2.8 years in myeloid neoplasia (n = 15; 95% CI: 0.3-2.6, 0.6-2.9, and 0.4-5.3, respectively; P < .001). Outcomes were poorest for SHM patients treated for CLL (HR 2.76, 95% CI 1.4-5.5, P = 0.003). A higher proportion of men and younger age were found in SHM patients (median age 66 vs 72 years in non-SHM; P < .001; men 68% vs 57%, P = .03). Myeloid neoplasia was rare (incidence rate 1/1000 person-years; 95% CI: 0.6-1.5) and tended to occur later than DLBCL in patients treated for CLL (median time from CLL to SHM 62 vs 45 months; P = .09). CONCLUSIONS: SHM and especially myeloid malignancies were rare in chemoimmunotherapy era.
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Leucemia Linfocítica Crónica de Células B/epidemiología , Neoplasias Primarias Secundarias/epidemiología , Anciano , Susceptibilidad a Enfermedades , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Leucemia Linfocítica Crónica de Células B/tratamiento farmacológico , Masculino , Persona de Mediana Edad , Síndromes Mielodisplásicos/epidemiología , Síndromes Mielodisplásicos/etiología , Neoplasias Primarias Secundarias/etiología , Noruega/epidemiología , Pronóstico , Vigilancia en Salud Pública , Sistema de RegistrosRESUMEN
The interaction of hematopoietic stem and progenitor cells with their direct neighboring cells in the bone marrow (the so called hematopoietic niche) evolves as a key principle for understanding physiological and malignant hematopoiesis. Significant progress in this matter has recently been achieved making use of emerging high-throughput techniques that allow characterization of the bone marrow microenvironment at single cell resolution. This review aims to discuss these single cell findings in the light of other conventional niche studies that together define the current notion of the niche's implication in i) normal hematopoiesis, ii) myeloid neoplasms and iii) disease-driving pathways that can be exploited to establish novel therapeutic strategies in the future.
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Médula Ósea/metabolismo , Leucemia Mieloide/metabolismo , Trastornos Mieloproliferativos/metabolismo , Animales , Médula Ósea/fisiología , Células de la Médula Ósea/metabolismo , Hematopoyesis/fisiología , Células Madre Hematopoyéticas/metabolismo , Humanos , Leucemia Mieloide/fisiopatología , Síndromes Mielodisplásicos/patología , Neoplasias/metabolismo , Nicho de Células Madre , Microambiente TumoralRESUMEN
This article describes the indications for sampling of bone marrow, the technical aspects of obtaining marrow core biopsies and aspirates, and the preparation of marrow smears. All aspects are illustrated with clinical cases. The information that can be expected from the pathologist's report of marrow samples is outlined, and the clinical features and prognosis of different types of leukemia are detailed.
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Enfermedades de la Médula Ósea/veterinaria , Médula Ósea/patología , Enfermedades de los Caballos/patología , Caballos/sangre , Animales , Enfermedades de la Médula Ósea/sangre , Enfermedades de la Médula Ósea/patología , Femenino , Enfermedades de los Caballos/sangre , Leucemia/sangre , Leucemia/patología , Leucemia/veterinaria , Patología Clínica , Pronóstico , Manejo de EspecímenesRESUMEN
OBJECTIVE: To improve monitoring of myeloid neoplasms by flow cytometry-based minimal residual disease (MRD) analysis, we analyzed the significance of leukemia-associated immunophenotype (LAIP) markers in 44 patients. METHODS: In a pilot study cohort, peripheral blood or bone marrow samples from 13 patients with myeloid neoplasms and one case of B lymphoblastic leukemia in complete hematologic remission after allogeneic bone marrow or stem cell transplantation were subjected to selection for leukemia-specific phenotypes by fluorescence-activated cell sorting using individual marker combinations, followed by PCR-based chimerism analysis. RESULTS: The feasibility of this method could be demonstrated, with selection being successful in 12 cases, including two cases where mixed chimerism was found exclusively in sorted cells. Interestingly, four specimens displayed full donor chimerism in cells expressing the presumably aberrant combination CD34+ /CD7+ . Further analyses, including assessment of an independent cohort of 25 patients not affected by neoplastic bone marrow infiltration, revealed that normal myeloid precursors usually include a population coexpressing CD34, CD13, CD33, and CD7. CONCLUSION: We conclude that the combination CD34+ /CD7+ might not be suitable as an LAIP for MRD diagnostics and that a subset of normal myeloid precursors in the bone marrow expresses CD7.
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Antígenos CD34/metabolismo , Antígenos CD7/metabolismo , Células Progenitoras Mieloides/metabolismo , Antígenos CD7/genética , Biomarcadores , Células de la Médula Ósea/metabolismo , Células de la Médula Ósea/patología , Expresión Génica , Humanos , Inmunofenotipificación , Leucemia Mieloide/diagnóstico , Leucemia Mieloide/genética , Leucemia Mieloide/metabolismo , Células Progenitoras Mieloides/patología , Neoplasia Residual/diagnóstico , Neoplasia Residual/genética , Neoplasia Residual/metabolismoRESUMEN
Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasm characterized by constitutive activation of extracellular signal-regulated kinase (ERK). Genomic characterization has identified activating point mutations including mutually exclusive BRAFV600E and activating MAP2K1 mutations to be responsible for ERK activation in a majority of pediatric LCH patients. Here, we report the discovery of a novel BRAF kinase fusion, PACSIN2-BRAF, in a child with multisystem LCH. This is the second reported case of an activating BRAF kinase fusion and indicates a recurrent pathologic mechanism. Genomic evaluation for activating kinase fusions should be strongly considered in pediatric LCH patients lacking more common mutations.
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Proteínas Adaptadoras Transductoras de Señales/genética , Quinasas MAP Reguladas por Señal Extracelular , Histiocitosis de Células de Langerhans/genética , Proteínas de Fusión Oncogénica/genética , Proteínas Proto-Oncogénicas B-raf/genética , Niño , Activación Enzimática/genética , Humanos , MasculinoRESUMEN
Langerhans cell histiocytosis (LCH) is an inflammatory neoplasia of myeloid precursor cells driven by mutations in the mitogen-activated protein kinase pathway. When disease involves the skin, LCH most commonly presents as a seborrheic dermatitis or eczematous eruption on the scalp and trunk. Evaluation for involvement of other organ systems is essential, because 9 of 10 patients presenting with cutaneous disease also have multisystem involvement. Clinical manifestations range from isolated disease with spontaneous resolution to life-threatening multisystem disease. Prognosis depends on involvement of risk organs (liver, spleen, and bone marrow) at diagnosis, particularly on presence of organ dysfunction, and response to initial therapy. Systemic treatment incorporating steroids and cytostatic drugs for at least one year has improved prognosis of multisystem LCH and represents the current standard of care.
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Histiocitosis de Células de Langerhans/patología , Histiocitosis de Células de Langerhans/terapia , Multimorbilidad , Adolescente , Biopsia con Aguja , Niño , Preescolar , Progresión de la Enfermedad , Femenino , Histiocitosis de Células de Langerhans/clasificación , Histiocitosis de Células de Langerhans/epidemiología , Humanos , Inmunohistoquímica , Incidencia , Masculino , Pronóstico , Enfermedades Raras , Medición de Riesgo , Índice de Severidad de la EnfermedadRESUMEN
Pseudokinases lack conserved motifs typically required for kinase activity. Nearly half of pseudokinases bind ATP, but only few retain phosphotransfer activity, leaving the functional role of nucleotide binding in most cases unknown. Janus kinases (JAKs) are nonreceptor tyrosine kinases with a tandem pseudokinase-kinase domain configuration, where the pseudokinase domain (JAK homology 2, JH2) has important regulatory functions and harbors mutations underlying hematological and immunological diseases. JH2 of JAK1, JAK2, and TYK2 all bind ATP, but the significance of this is unclear. We characterize the role of nucleotide binding in normal and pathogenic JAK signaling using comprehensive structure-based mutagenesis. Disruption of JH2 ATP binding in wild-type JAK2 has only minor effects, and in the presence of type I cytokine receptors, the mutations do not affect JAK2 activation. However, JH2 mutants devoid of ATP binding ameliorate the hyperactivation of JAK2 V617F. Disrupting ATP binding in JH2 also inhibits the hyperactivity of other pathogenic JAK2 mutants, as well as of JAK1 V658F, and prevents induction of erythrocytosis in a JAK2 V617F myeloproliferative neoplasm mouse model. Molecular dynamic simulations and thermal-shift analysis indicate that ATP binding stabilizes JH2, with a pronounced effect on the C helix region, which plays a critical role in pathogenic activation of JAK2. Taken together, our results suggest that ATP binding to JH2 serves a structural role in JAKs, which is required for aberrant activity of pathogenic JAK mutants. The inhibitory effect of abrogating JH2 ATP binding in pathogenic JAK mutants may warrant novel therapeutic approaches.
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Adenosina Trifosfato/metabolismo , Janus Quinasa 2/genética , Janus Quinasa 2/metabolismo , Mutación Missense , Adenosina Trifosfato/química , Animales , Sitios de Unión/genética , Células COS , Línea Celular Tumoral , Chlorocebus aethiops , Activación Enzimática/genética , Femenino , Humanos , Immunoblotting , Janus Quinasa 2/química , Ratones Endogámicos C57BL , Simulación de Dinámica Molecular , Trastornos Mieloproliferativos/enzimología , Trastornos Mieloproliferativos/genética , Trastornos Mieloproliferativos/metabolismo , Fosforilación , Unión Proteica , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Receptores de Eritropoyetina/metabolismoRESUMEN
The paper presents new molecular data, the principles of the classification of myeloid neoplasms, and criteria for their diagnosis according to the new edition of the WHO Classification of Tumors of Hematopoietic and Lymphoid Tissues, 2017. Current concepts of clonal hematopoiesis and models of clonal evolution are presented to characterize the common features of the molecular pathogenesis of myeloid neoplasms. There are new data and general principles of diagnosis of myeloid neoplasms: Ph-negative myeloproliferative diseases, myelodysplastic syndromes, myeloid/lymphoid neoplasms with eosinophilia and rearrangements of PDGFRA, PDGFRB, FGFR1, and PCM1-JAK2, diseases from the group of myelodysplastic/myeloproliferative diseases. Emphasis is laid on the possibilities and limitations of pathological differential diagnosis when a pathologist examines bone marrow trepanobiopsy specimens in his/her routine work.
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Neoplasias de la Médula Ósea , Síndromes Mielodisplásicos , Trastornos Mieloproliferativos , Neoplasias , Neoplasias de la Médula Ósea/clasificación , Neoplasias de la Médula Ósea/diagnóstico , Trasplante de Células Madre Hematopoyéticas , Humanos , Tejido Linfoide , Síndromes Mielodisplásicos/clasificación , Síndromes Mielodisplásicos/diagnóstico , Trastornos Mieloproliferativos/clasificación , Trastornos Mieloproliferativos/diagnósticoRESUMEN
Langerhans cell histiocytosis (LCH), the most common histiocytic disorder, is characterized by the accumulation of CD1A(+) /CD207(+) mononuclear phagocytes within granulomatous lesions that can affect nearly all organ systems. Historically, LCH has been presumed to arise from transformed or pathologically activated epidermal dendritic cells called Langerhans cells. However, new evidence supports a model in which LCH occurs as a consequence of a misguided differentiation programme of myeloid dendritic cell precursors. Genetic, molecular and functional data implicate activation of the ERK signalling pathway at critical stages in myeloid differentiation as an essential and universal driver of LCH pathology. Based on these findings, we propose that LCH should be re-defined as an inflammatory myeloid neoplasia. Increased understanding of LCH pathogenesis will provide opportunities to optimize and personalize therapy through improved risk-stratification, targeted therapy and assessment of therapy response based on specific molecular features and origin of the pathological myeloid cells.
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Diferenciación Celular , Histiocitosis de Células de Langerhans , Células de Langerhans , Modelos Biológicos , Células Mieloides , Neoplasias , Antígenos CD/metabolismo , Antígenos CD1/metabolismo , Histiocitosis de Células de Langerhans/clasificación , Histiocitosis de Células de Langerhans/metabolismo , Histiocitosis de Células de Langerhans/patología , Histiocitosis de Células de Langerhans/terapia , Humanos , Células de Langerhans/metabolismo , Células de Langerhans/patología , Lectinas Tipo C/metabolismo , Sistema de Señalización de MAP Quinasas , Lectinas de Unión a Manosa/metabolismo , Células Mieloides/metabolismo , Células Mieloides/patología , Neoplasias/clasificación , Neoplasias/metabolismo , Neoplasias/patología , Neoplasias/terapiaRESUMEN
Polycythemia Vera (PV) is typically caused by V617F or exon 12 JAK2 mutations. Little is known about Polycythemia cases where no JAK2 variants can be detected, and no other causes identified. This condition is defined as idiopathic erythrocytosis (IE). We evaluated clinical-laboratory parameters of a cohort of 56 IE patients and we determined their molecular profile at diagnosis with paired blood/buccal-DNA exome-sequencing coupled with a high-depth targeted OncoPanel to identify a possible underling germline or somatic cause. We demonstrated that most of our cohort (40/56: 71.4%) showed no evidence of clonal hematopoiesis, suggesting that IE is, in large part, a germline disorder. We identified 20 low mutation burden somatic variants (Variant allelic fraction, VAF, < 10%) in only 14 (25%) patients, principally involving DNMT3A and TET2. Only 2 patients presented high mutation burden somatic variants, involving DNMT3A, TET2, ASXL1 and WT1. We identified recurrent germline variants in 42 (75%) patients occurring mainly in JAK/STAT, Hypoxia and Iron metabolism pathways, among them: JAK3-V722I and HIF1A-P582S; a high fraction of patients (48.2%) resulted also mutated in homeostatic iron regulatory gene HFE-H63D or C282Y. By generating cellular models, we showed that JAK3-V722I causes activation of the JAK-STAT5 axis and upregulation of EPAS1/HIF2A, while HIF1A-P582S causes suppression of hepcidin mRNA synthesis, suggesting a major role for these variants in the onset of IE.