Inflammatory Myopathies & Innovative Therapies

Myositis are rare diseases that have been misclassified, which explains why, to date, the majority of randomized controlled trials testing different immunosuppressants have failed to achieve their primary objective. These trials mixed pathologies with poorly characterized pathophysiological mechanisms and tested non-targeted treatments. Our goal is to improve the treatment of myositis using a translational approach.

To achieve this goal, our strategy, based on our clinical database and biobank (1300 patients), consists in (i) defining homogeneous groups of patients to (ii) identify biomarkers of prognosis and/or disease activity and (iii) characterize pathomechanisms using in vivo and in vitro models to (iv) propose new therapeutic strategies.

 1- Definition of homogeneous groups of patients: Myositis specific antibodies: standardization of detection and characterization of the new entity myositis under immune checkpoint inhibitors.

Over the last 5 years, we have refined the classification of spontaneous myositis and have demonstrated, with others, the crucial role of myositis specific antibodies to diagnose and classify myositis patients into homogeneous groups. To this end, we refined the definition of autoimmune necrotizing myopathies (ENMC 2017 criteria Allenbach et al.) and dermatomyositis (ENMC 2018 criteria, Benveniste et al.) at an international workshop we organized.

We now aim to standardize the detection of myositis specific antibodies, as there are differences between the commercial detection kits available worldwide. We intend to organize an international workshop to address this issue in October 2020.

In recent years, a new form of myositis has emerged. The Immune Checkpoint Inhibitor (ICI) is a major breakthrough in the treatment of cancer. Programmed Cell Death Molecules 1 (PD1) and Cytotoxic T-cell Antigen 4 (CTLA-4) regulate T cell activation. To restore anti-tumor immunity, specific inhibitors of these pathways have been developed. While ICIs significantly improve the prognosis of cancer patients, they frequently expose them to immunomediated adverse events (irAE). Indeed, inhibition of T cell checkpoints can also activate natural autoimmune T cells. We have reported the largest series of ICI-induced myositis, demonstrating that the disease differs from spontaneous myositis in terms of phenotype and high mortality rate (Anquetil et al Circulation 2018 and M Touat et al Neurology 2018).

We aim to create a national and European registry for this condition in order to better characterize the disease: risk factors and prognostic factors using our spontaneous myositis cohort and cancer patients as controls. As we have previously done to define a homogeneous group of spontaneous myositis (K. Mariampillay et al. JAMA Neurology 2018), we will use unsupervised analysis (by multiple correspondence analysis and then by hierarchical analysis) to determine, without preconception, homogeneous groups of patients. This is crucial given the considerable increase in the prescription of ICI and the frequency of irAE. IRAEs are becoming a major problem in oncology and ICI-induced myositis now has a frequency similar to that of a subgroup of spontaneous myositis.

2- Define new biomarkers of disease activity and prognosis: interferon levels and myostatin.

While inclusion myositis and autoimmune necrotizing myopathies are both muscle-restricted conditions, both dermatomyositis and anti-synthetase syndrome are systemic and therefore difficult to assess. We and others have demonstrated that interferon type I (IFN-I) plays a key role in dermatomyositis, while for anti-synthetase syndrome it remains less established. For example, we hypothesize that IFN levels (type I or II) may be a biomarker to monitor disease activity. Based on our biobank, we have tested IFN levels using ultra-sensitive tools (SiMoA) as well as IFN-stimulating gene signatures (submitted paper). Immune-mediated necrotizing myopathies are serious conditions with poor muscle strength recovery linked to significant muscle damage. Early muscle damage is difficult to assess as a predictor of muscle recovery. We also aim to identify such biomarkers and, as a first step, we will test the level of myostatin, as this member of the transforming growth factor-beta superfamily is a negative regulator of skeletal muscle growth and development.

3- Exploring new pathophysiological mechanisms

3.1 Pathogenic role of myositis specific antibodies. We have previously shown that antibodies specific to autoimmune necrotizing myopathies in vitro were pathogenic whereas these antibodies target intracytoplasmic ubiquitous epitopes. Through the ANR-CJC CAMANAI grant, we aim to (i) produce human monoclonal antibodies specific for autoimmune necrotizing myopathies, (ii) identify HLA-DR-11 T cells specific for the epitope (collaboration with Pr Mallone Institut Cochin), and (iii) establish a mouse model of the disease to clarify the pathophysiology. We also plan to test the pathogenic role of myositis specific antibodies on 3D muscle cell cultures (collaboration with Dr. P. Gilbert, Canada).

3.2 Role of muscle fibers in myositis. The vast majority of myositis studies have focused on immune cells in muscle tissue, while the effect of the inflammatory environment on muscle fibers remains poorly studied. This is crucial for muscle function, muscle damage and muscle repair. To address these points, we will perform an analysis of individual cells by collecting muscle fiber nuclei from muscle biopsies of patients with myositis. With this innovative tool, we will be able to analyze and compare the transcriptome of muscle fibers in relation to inflammatory cells. This analysis will also be combined with the new spatial transcriptomic analysis technology. This transcriptomic analysis at the level of a single cell will be validated at the protein level using another innovative tool (Imaging Mass Cytometry – Hyperion®). In parallel, proteomic and transcriptomic analysis of cultured muscle cells from myositis will be analyzed to measure and analyze the pathway involved in muscle regeneration.

3.3 ICI-induced myositis. In this new entity, we were able to characterize inflammatory infiltrates within muscle tissue by showing that CD8+ T cells were predominant while the pathomechanism of the disease remains to be defined. Using the above-mentioned technique, single cell analysis, spatial transcriptomic and mass cytometry imaging, we will achieve this goal.  This field is also completely new and, based on our expertise and previous publications, we wish to maintain our lead in this new field.

4- Develop a new therapeutic strategy: 4 clinical trials using targeted treatments

4.1 Dermatomyositis: Clinical Trial. Based on the results obtained, which show the pathogenic role of IFN, we have recently received funding to conduct a multi-center randomized clinical trial to test a JAK inhibitor (blocking the IFN pathway) in dermatomyositis (PHRC 2018 BIRD; n=62; PI Y. Allenbach starts in September 2020). This RCT will be the first to test this innovative approach in adults.

4.2 Autoimmune Necrotizing Myopathies: Clinical Trial. The results obtained in collaboration with O. Boyer (IRIB Rouen) showed the crucial role of autoantibodies (anti-SRP and anti-HMGCR) and the complement pathway in the pathogenesis of immune-mediated necrotizing myopathies (IMNM). These results have led to the development of an international multicenter randomized phase II clinical trial testing a complement Inhibitor (Zilucoplan) funded by Ra Pharma Company ®. This randomized clinical trial will be the first to test this innovative approach in IMNM.

4.3 Inclusion body myositis. For this rare type of myositis, no treatment is currently recommended, in particular immunosuppressants are ineffective. Neurodegenerative pathways (deficiency of the proteasomal/lysosome pathway, accumulation of amyloid proteins) also aggravate this myopathy (Benveniste O, ActaNeuropath, 2015). We conducted a prospective study on 22 patients ( Identifier: NCT00898989) to study their immune responses (Y Allenbach, PLoS One, 2014) using classical flow cytometry and more recently we refined the analysis using mass cytometry (Dzangue et. Al 2019 Autom-immune review).  Based on the preclinical studies we have conducted (Allenbach, Am J Pathol 2009 and N Prevel, PLoS One 2014), we recently conducted a randomized clinical trial showing that rapamycin (versus placebo) (RAPAMI, NCT02481453, n=44) can slow disease progression (submitted article). Since it was not possible to improve muscle strength in this severe condition, we recently proposed to restore muscle strength using cell therapy with the stromal vascular fraction (rich in stem cells). This cell extract obtained from adipose tissue can differentiate into several lineages, including muscle tissue. We were awarded a grant (PHRC-N 2018; PI O. Benveniste) to conduct a Phase I clinical trial to test the effect of injecting patients with non-dominant inclusion arm myositis with their autologous stromal vascular fraction cells obtained from adipose tissue (after liposuction). The outcomes will be grip muscle strength and muscle mass assessed by quantitative MRI. This trial will begin in 2020.

4.4 Myositis induced under ICI: We have shown (JE Salem NEJM 2019) that CTLA4-Ig (Abatacept) can help patients with severe concomitant myositis and myocarditis.A therapeutic trial led by PI JE Salem is currently fundraising to test Abatacept in an RCT in patients with severe irAE.

Equipe Benveniste
Olivier Benveniste
Yves Allenbach


213 documents

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Assistance Publique Hôpitaux de Paris
Agence nationale de la recherche
The Myositis Association
Association VLM
CSL Behring
The Uehara Memorial Foundation

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