Daratumumab displays in vitro and in vivo anti-tumor activity in models of B-cell non-Hodgkin lymphoma and improves responses to standard chemo-immunotherapy regimens

Altres ajuts: This work was carried out at the Esther Koplowitz Center, Barcelona. Genmab and Janssen pharmaceuticals funded this research. Additional grants that contributed to this work included: [...], and CIBERONC (CB16/12/00334 and CB16/12/00225).CD38 is expressed in several types of non-Hodgkin lymphoma (NHL) and constitutes a promising target for antibody-based therapy. Daratumumab (Darzalex) is a first-in-class anti-CD38 antibody approved for the treatment of relapsed/refractory (R/R) multiple myeloma (MM). It has also demonstrated clinical activity in Waldenström macroglobulinaemia and amyloidosis. Here, we have evaluated the activity and mechanism of action of daratumumab in preclinical in vitro and in vivo models of mantle cell lymphoma (MCL), follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL), as monotherapy or in combination with standard chemo-immunotherapy. In vitro, daratumumab engages Fc-mediated cytotoxicity by antibody-dependent cell cytotoxicity and antibody-dependent cell phagocytosis in all lymphoma subtypes. In the presence of human serum, complement-dependent cell cytotoxicity was marginally engaged. We demonstrated by Selective Plane Illumination Microscopy that daratumumab fully penetrated a three-dimensional (3D) lymphoma organoid and decreased organoid volume. In vivo, daratumumab completely prevents tumor outgrowth in models of MCL and FL, and shows comparable activity to rituximab in a disseminated in vivo model of blastic MCL. Moreover, daratumumab improves overall survival (OS) in a mouse model of transformed CD20 FL, where rituximab showed limited activity. Daratumumab potentiates the antitumor activity of CHOP and R-CHOP in MCL and FL xenografts. Furthermore, in a patient-derived DLBCL xenograft model, daratumumab anti-tumor activity was comparable to R-CHOP and the addition of daratumumab to either CHOP or R-CHOP led to full tumor regression. In summary, daratumumab constitutes a novel therapeutic opportunity in certain scenarios and these results warrant further clinical development

NG2 antigen is involved in leukemia invasiveness and central nervous system infiltration in MLL-rearranged infant B-ALL

Mixed-lineage leukemia (MLL)-rearranged (MLLr) infant B-cell acute lymphoblastic leukemia (iMLLr-B-ALL) has a dismal prognosis and is associated with a pro-B/mixed phenotype, therapy refractoriness and frequent central nervous system (CNS) disease/relapse. Neuron-glial antigen 2 (NG2) is specifically expressed in MLLr leukemias and is used in leukemia immunophenotyping because of its predictive value for MLLr acute leukemias. NG2 is involved in melanoma metastasis and brain development; however, its role in MLL-mediated leukemogenesis remains elusive. Here we evaluated whether NG2 distinguishes leukemia-initiating/propagating cells (L-ICs) and/or CNS-infiltrating cells (CNS-ICs) in iMLLr-B-ALL. Clinical data from the Interfant cohort of iMLLr-B-ALL demonstrated that high NG2 expression associates with lower event-free survival, higher number of circulating blasts and more frequent CNS disease/relapse. Serial xenotransplantation of primary MLL-AF4 + leukemias indicated that NG2 is a malleable marker that does not enrich for L-IC or CNS-IC in iMLLr-B-All. However, NG2 expression was highly upregulated in blasts infiltrating extramedullar hematopoietic sites and CNS, and specific blockage of NG2 resulted in almost complete loss of engraftment. Indeed, gene expression profiling of primary blasts and primografts revealed a migratory signature of NG2 + blasts. This study provides new insights on the biology of NG2 in iMLLr-B-ALL and suggests NG2 as a potential therapeutic target to reduce the risk of CNS disease/relapse and to provide safer CNS-directed therapies for iMLLr-B-ALL

A Single-Run Next-Generation Sequencing (NGS) Assay for the Simultaneous Detection of Both Gene Mutations and Large Chromosomal Abnormalities in Patients with Myelodysplastic Syndromes (MDS) and Related Myeloid Neoplasms

Chromosomal abnormalities and somatic mutations are found in patients with myelodysplastic syndromes (MDS) and myelodysplastic/myeloproliferative neoplasms (MDS/MPN) in around 50-80% of cases. The identification of these alterations is important for the accurate diagnosis and prognostic classification of these patients. Often, an apparently normal or failed karyotype might lead to an inadequate estimation of the prognostic risk, and several strategies should be combined to solve these cases. The aim of this study was to introduce a novel next-generation sequencing (NGS)-based strategy for the simultaneous detection of all the clinically relevant genetic alterations associated with these disorders. We validated this approach on a large cohort of patients by comparing our findings with those obtained with standard-of-care methods (i.e., karyotype and SNP-arrays). We show that our platform represents a significant improvement on current strategies in defining diagnosis and risk stratification of patients with MDS and myeloid-related disorders. Myelodysplastic syndromes (MDS) and myelodysplastic/myeloproliferative neoplasms are clonal disorders that share most of their cytogenetic and molecular alterations. Despite the increased knowledge of the prognostic importance of genetics in these malignancies, next-generation sequencing (NGS) has not been incorporated into clinical practice in a validated manner, and the conventional karyotype remains mandatory in the evaluation of suspected cases. However, non-informative cytogenetics might lead to an inadequate estimation of the prognostic risk. Here, we present a novel targeted NGS-based assay for the simultaneous detection of all the clinically relevant genetic alterations associated with these disorders. We validated this platform in a large cohort of patients by performing a one-to-one comparison with the lesions from karyotype and single-nucleotide polymorphism (SNP) arrays. Our strategy demonstrated an approximately 97% concordance with standard clinical assays, showing sensitivity at least equivalent to that of SNP arrays and higher than that of conventional cytogenetics. In addition, this NGS assay was able to identify both copy-neutral loss of heterozygosity events distributed genome-wide and copy number alterations, as well as somatic mutations within significant driver genes. In summary, we show a novel NGS platform that represents a significant improvement to current strategies in defining diagnosis and risk stratification of patients with MDS and myeloid-related disorder

Caracterización de la púrpura trombótica trombocitopénica congénita mediante técnicas inmunológicas y moleculares: resultados de la colección nacional del GEPTT

CO-093 Introducción: La Púrpura Trombótica Trombocitopénica congénita (PTTc) es una enfermedad ultra-rara caracterizada por un déficit severo de la enzima ADAMTS13 como consecuencia de mutaciones heredadas de forma autosómica recesiva en el gen ADAMTS13 (9q34). En este estudio, desarrollado dentro del Grupo Cooperativo Español de PTT (GEPTT), se ha llevado a cabo la creación de una colección centralizada de muestras biológicas y su caracterización inmunológica y molecular para mejorar el diagnóstico y el manejo clínico de los pacientes. Métodos: Se incluyeron en este estudio seis pacientes con diagnóstico clínico o sospecha de PTTc de diferentes hospitales españoles. Se estudió la actividad de ADAMTS13 e inhibidores mediante la técnica ELISA con el kit “TECHNOZYM® ADAMTS-13 Activity e INH” (Technoclone). Además, se realizó test Bethesda para descartar la presencia de inhibidores no IgG. Para el estudio genético, se implementó un panel de captura (SureSelect, Agilent) dirigido a la región genómica completa, incluyendo también las regiones no codificantes, del gen ADAMTS13 (chr9: 136278459 - 136325025, hg19). Las librerías de DNA se secuenciaron con la plataforma MiSeq (Illumina®) y el posible efecto patogénico de las variantes identificadas se estudió a nivel de i) proteína, utilizando predictores de cambio de aminoácido (SIFT) y de estructura de la proteína (SwissModel) y ii) splicing, con herramientas de análisis in silico (HSF) y validación funcional in vitro mediante minigenes. En 3 casos se realizó un cariotipo molecular utilizando array de SNPs (CytoScan HD, Affymetrix) para detectar regiones de pérdida de material genético y/o de heterocigosidad (LOH). Resultados: La mediana de actividad de ..

Acute loss of TET function results in aggressive myeloid cancer in mice

TET-family dioxygenases oxidize 5-methylcytosine (5mC) in DNA, and exert tumour suppressor activity in many types of cancers. Even in the absence of TET coding region mutations, TET loss-of-function is strongly associated with cancer. Here we show that acute elimination of TET function induces the rapid development of an aggressive, fully-penetrant and cell-autonomous myeloid leukaemia in mice, pointing to a causative role for TET loss-of-function in this myeloid malignancy. Phenotypic and transcriptional profiling shows aberrant differentiation of haematopoietic stem/progenitor cells, impaired erythroid and lymphoid differentiation and strong skewing to the myeloid lineage, with only a mild relation to changes in DNA modification. We also observe progressive accumulation of phospho-H2AX and strong impairment of DNA damage repair pathways, suggesting a key role for TET proteins in maintaining genome integrityopen0

Hypoxia-inducible Factor-1 Activation in Nonhypoxic Conditions: The Essential Role of Mitochondrial-derived Reactive Oxygen Species

Hypoxia-inducible factor-1 (HIF-1) is a key transcription factor for responses to low oxygen. Here we report that the generation of mitochondrial reactive oxygen species are essential for regulating HIF-1 in normal oxygen conditions in the vasculature

The earliest thymic T cell progenitors sustain B cell and myeloid lineage potential

The stepwise commitment from hematopoietic stem cells in the bone marrow to T lymphocyte-restricted progenitors in the thymus represents a paradigm for understanding the requirement for distinct extrinsic cues during different stages of lineage restriction from multipotent to lineage-restricted progenitors. However, the commitment stage at which progenitors migrate from the bone marrow to the thymus remains unclear. Here we provide functional and molecular evidence at the single-cell level that the earliest progenitors in the neonatal thymus had combined granulocyte-monocyte, T lymphocyte and B lymphocyte lineage potential but not megakaryocyte-erythroid lineage potential. These potentials were identical to those of candidate thymus-seeding progenitors in the bone marrow, which were closely related at the molecular level. Our findings establish the distinct lineage-restriction stage at which the T cell lineage-commitment process transits from the bone marrow to the remote thymus. © 2012 Nature America, Inc. All rights reserved

Initial seeding of the embryonic thymus by immune-restricted lympho-myeloid progenitors

The final stages of restriction to the T cell lineage occur in the thymus after the entry of thymus-seeding progenitors (TSPs). The identity and lineage potential of TSPs remains unclear. Because the first embryonic TSPs enter a non-vascularized thymic rudiment, we were able to directly image and establish the functional and molecular properties of embryonic thymopoiesis-initiating progenitors (T-IPs) before their entry into the thymus and activation of Notch signaling. T-IPs did not include multipotent stem cells or molecular evidence of T cell-restricted progenitors. Instead, single-cell molecular and functional analysis demonstrated that most fetal T-IPs expressed genes of and had the potential to develop into lymphoid as well as myeloid components of the immune system. Moreover, studies of embryos deficient in the transcriptional regulator RBPJ demonstrated that canonical Notch signaling was not involved in pre-thymic restriction to the T cell lineage or the migration of T-IPs