A first-in-class Wiskott-Aldrich syndrome protein activator with anti-tumor activity in hematologic cancers

Hematological cancers are among the most common cancers in adults and children. Despite significant improvements in therapies, many patients still succumb to the disease. Therefore, novel therapies are needed. The Wiskott-Aldrich syndrome protein (WASp) family regulates actin assembly in conjunction with the Arp2/3 complex, a ubiquitous nucleation factor. WASp is expressed exclusively in hematopoietic cells and exists in two allosteric conformations: autoinhibited or activated. Here, we describe the development of EG-011, a first-in-class small molecule activator of the WASp auto-inhibited form. EG-011 possesses in vitro and in vivo anti-tumor activity as a single agent in lymphoma, leukemia, and multiple myeloma, including models of secondary resistance to PI3K, BTK, and proteasome inhibitors. The in vitro activity was confirmed in a lymphoma xenograft. Actin polymerization and WASp binding was demonstrated using multiple techniques. Transcriptome analysis highlighted homology with drugs-inducing actin polymerization

Nouvelle prédisposition génétique à l'auto-immunité précoce chez l'homme : implication de la voie NFkB

Le lupus érythémateux systémique (LES) est une maladie auto-immune et inflammatoire caractérisée par une production excessive d'auto-anticorps et de cytokines pro-inflammatoires, notamment l'interféron de type 1. Afin d'identifier de nouveaux facteurs génétiques associés au LES, un whole exome sequencing (WES) nous a permis d'identifier deux mutations différentes du gène RELA chez 3 patients LES ayant débuté à l'âge adulte ou pédiatrique. RELA code la protéine p65 qui est une sous-unité du facteur de transcription NF-κB. Les mutations retrouvées H86N et R329X de RELA conduisent à l'activation constitutive de la voie NF-κB dans lymphocytes des patients, illustrée par une localisation nucléaire spontanée. Ces trois patients présentent également une expression élevée des gènes stimulés par l'interféron (ISG). En parallèle, la co-expression, dans une lignée cellulaire immortalisée, de la forme sauvage et mutante de RELA et d'un gène rapporteur (Luciferin) sous le contrôle d'un promoteur IFN-I, a confirmé l'implication des mutants de RELA dans la production de l'interféron de type I. De plus, une mutation de novo du gène RELB a été identifié chez un patient présentant un syndrome poly-autoimmun de type IPEX. De même que pour les mutants RELA, le mutant RELB conduit à une relocalisation nucléaire de RELB/p62 à l'état basal entrainant une activité spontanée de la voie NF-κB. De plus, la forme mutée de RELB est associée à une augmentation de la production d'IFN de type I. L'ensemble de ces nouvelles données démontre le rôle essentiel de RELA et RELB dans la régulation de la voie de l'interféron de type 1 dans les maladies auto-immunes.We have identified 2 different heterozygous mutations of RELA (a missense mutation H86N, and a non-sense R329X), coding the p65 protein, one of the transcription factors of the canonical NFκB pathway, in 3 patients presenting with adult or pediatric onset of Systemic Lupus Erythematous (SLE). The nuclear factor-kappa B (NFκB) transcription factor plays a critical role in diverse cellular processes associated with proliferation, cell death, development, as well as innate and adaptive immune responses. NFκB is normally sequestered in the cytoplasm by a family of inhibiteins kntory proown IκBs. The signal pathways leading to the nuclear accumulation of NFκB, which can be activated by a wide variety of stimuli, have been extensively studied in the past two decades. After its translocation to the nucleus, NFκB must be actively regulated to execute its function as a transcription factor. NFκB has long been considered as a target for new anti-inflammatory drugs. However, data from genetic studies in mice suggest that NFκB could be a complex therapeutic target in inflammatory diseases as it regulates proinflammatory cytokine production, but also leukocyte recruitment, or cell survival. By confocal microscopy analysis combined to molecular analysis in vitro, we showed that these mutations lead to the expression of mutant RelA and spontaneous activation of the NFκB pathway in non-stimulated patients' T cells suggesting a role of RELA mutants in the control of the adaptive immunity. Moreover, we found that patients mutated for RELA displayed a high Interferon Stimulated Genes (ISGs) expression in total Peripheral Blood Mononuclear Cells (PBMCs) as well as in activated T cells and immortalized B cells by Epstein Barr Virus (B-EBV), indicating a lymphocyte-intrinsic dysregulation of the Interferon type I (IFN-I) production. By expression of the mutants into cell lines we observed that the co-expression of the RELA wild type and mutant forms were required to activate the IFNb promoter. These results suggest that the mutant RELA is hijacking the WT RELA towards the interferon promoter, leading to an unregulated production of type-I IFN which is therefore the initial event of the SLE onset in these patients. Upregulation of the type I IFN as well as type II IFN has also been found in a patient with IPEX-like syndrome, where no mutation on FOXP3 has been identified. We identified a de novo mutation in RELB, the transcriptional factor of the non-canonical NF-kB pathway, localized in the transactivation domain of the gene, important for its transcriptional activity. First functional assays show that the mutation acts like a gain of function. Gain of function mutations of RELB has been associated with non-Hodgkin lymphomas, rather than autoimmunity. Moreover, the RNA sequencing performed on the cells of the patient shows a cross-link between canonical and non-canonical NF-kB pathway. In conclusion, the aim of this thesis was to describe the role of the NFkB pathway in autoimmune diseases and the crosstalk between this important pathway and type I and II IFN

NF-κB: At the Borders of Autoimmunity and Inflammation

International audienceThe transcription factor NF-kB regulates multiple aspects of innate and adaptive immune functions and serves as a pivotal mediator of inflammatory response. In the first part of this review, we discuss the NF-kB inducers, signaling pathways, and regulators involved in immune homeostasis as well as detail the importance of post-translational regulation by ubiquitination in NF-kB function. We also indicate the stages of central and peripheral tolerance where NF-kB plays a fundamental role. With respect to central tolerance, we detail how NF-kB regulates medullary thymic epithelial cell (mTEC) development, homeostasis, and function. Moreover, we elaborate on its role in the migration of double-positive (DP) thymocytes from the thymic cortex to the medulla. With respect to peripheral tolerance, we outline how NF-kB contributes to the inactivation and destruction of autoreactive T and B lymphocytes as well as the differentiation of CD4 +-T cell subsets that are implicated in immune tolerance. In the latter half of the review, we describe the contribution of NF-kB to the pathogenesis of autoimmunity and autoinflammation. The recent discovery of mutations involving components of the pathway has both deepened our understanding of autoimmune disease and informed new therapeutic approaches to treat these illnesses

Glucose homeostasis in acromegaly: pathogenesis and effects of treatment

Acromegaly is a chronic debilitating disorder resulting from excessive secretion of growth hormone (GH) and consequent increase in insulin-like growth factor I (IGF-I), usually caused by a pituitary somatotroph adenoma. Effective treatment aims to ameliorate symptoms and signs of the disease and to lower mortality rate. In particular, high morbidity and mortality are partly related to the presence of insulin resistance due to the action of GH on liver, muscle and adipose tissue. Insulin resistance and/or reduced insulin sensitivity physiologically result in hypersecretion of insulin from the pancreas. This compensatory state of hyperinsulinemia is felt to be a first and more important marker for this condition. Adequate control of GH excess by surgery or pharmacotherapy is associated with decreased insulin resistance, resulting in reduced plasma insulin and glucose levels or improved glucose tolerance. Despite divergent effects of both somatostatin and somatostatin analogs on GH, insulin and glucagon secretion, and glucose absorption, treatment with the somatostatin analogs octreotide and lanreotide has only limited effects on glucose metabolism. However, glucose sensitivity has been formally examined using a hyperinsulinemic euglycemic clamp only in a minority of studies. Treatment with the GH-receptor antagonist pegvisomant improves insulin sensitivity, thus decreasing circulating fasting insulin and glucose levels. Assessment of insulin secretion and glucose levels in acromegalic patients during administration of the above compounds is thus mandatory

Targeting IRAK4 with Emavusertib in Lymphoma Models with Secondary Resistance to PI3K and BTK Inhibitors

Inhibitors of phosphatidylinositol 3-kinase (PI3K) and Bruton tyrosine kinase (BTK) represent a recognized option for the treatment of patients affected by indolent B cell lymphomas. However, small molecules as single agents show limited success in their ability in inducing complete responses, with only partial remission achieved in most patients, suggesting the need for combination therapies. IRAK4 is a protein kinase downstream of the Toll-like receptor signaling (TLR), a driver pathway of secondary tumor° resistance in both hematological and solid tumor malignancies. Activation of IRAK4 upon TLRs and IL-1 receptor (IL-1R) stimulation and through the adaptor protein MYD88 initiates a signaling cascade that induces cytokine and survival factor expression mediated by the transcription factor NF-κB. MYD88-L265P encoding mutations occur in diffuse large B-cell lymphomas, in lymphoplasmacytic lymphomas and in few marginal zone lymphomas (MZL). The IRAK4 inhibitor emavusertib (CA-4948) has shown early safety and clinical activity in lymphoma and leukemia patients. In this preclinical study, we assessed emavusertib effectiveness in MZL, both as single agent and in combination with targeted agents, with a particular focus on its capability to overcome resistance to BTK and PI3K inhibitors. We showed that the presence of MYD88 L265P mutation in bona fide MZL cell lines confers sensitivity to the IRAK4 inhibitor emavusertib as single agent. Emavusertib-based combinations improved the sensitivity of MZL cells to BTK and PI3K inhibitors, including cells with a secondary resistance to these agents. Emavusertib exerted its activity via inhibition of NF-κB signaling and induction of apoptosis. Considering the early safety data from clinical trials, our study identifies the IRAK4 inhibitor emavusertib as a novel compound to be explored in trials for patients with MYD88-mutated indolent B cell lymphomas as single agent and as combination partner with BTK or PI3K inhibitors in unselected populations of patients