Refractory Myositis Research Articles

Updates in Treatment of Refractory Inflammatory Myositis

Idiopathic immune myopathies (IIM), also known as myositis, are a heterogeneous group of autoimmune diseases with varying phenotypes, prognoses, and treatment responses. They are primarily characterized by muscle inflammation, however, many patients have extramuscular involvement including skin rash, arthritis, interstitial lung disease (ILD), cardiomyopathy, and gastrointestinal dysmotility. The discovery of myositis-specific autoantibodies (MSAs) has been a major advancement in the field of IIMs, shaping the new landscape of the clinical, phenotypical, histological, and serological correlations. Based on this discovery, IIM can be more specifically classified into dermatomyositis (DM) (including amyopathic DM), antisynthetase syndrome (ASyS), immune-mediated necrotizing myopathy (IMNM), inclusion body myositis (IBM), polymyositis (PM), and overlap myositis (OM). An increasing number of histological studies have revealed a misdiagnosis of PM because many patients who were previously diagnosed with PM were later reclassified to other forms of IIM, including IBM, IMNM, ASyS, or DM without a rash.

A Unique Case of Dysferlinopathy Presenting as Refractory Myositis (P11-11.013)

A Unique Case of Dysferlinopathy Presenting as Refractory Myositis (P11-11.013)

Tofacitinib therapy in refractory inflammatory myositis: a retrospective cohort study of 41 patients.

To evaluate the efficacy and safety of tofacitinib in treatment-refractory inflammatory myositis in a real-world clinical setting. All patients with refractory inflammatory myositis treated with tofacitinib from a single urban centre in Vancouver, British Columbia, Canada, were included from June 2016 to December 2022. The medical records of these patients were retrospectively reviewed. A total of 41 patients were included, 23 with classic DM, 12 with amyopathic DM (ADM) and six with PM phenotype. The patients failed an average of four to five non-steroidal immunosuppressants before initiation of tofacitinib. In the classic DM and ADM group, tofacitinib offered clinically and statistically significant cutaneous improvement. In all myositis patients including the PM phenotype, no meaningful muscle strength response to tofacitinib was observed. 53.7% of the patients discontinued tofacitinib due to lack of benefit or death. Of the 19 patients who remained on tofacitinib at the conclusion of this study, tofacitinib demonstrated clinically and statistically significant improvement in cutaneous disease activity. Tofacitinib appears to be highly effective in targeting cutaneous manifestations in classic DM and ADM; however, minimal benefit in muscle strength in the DM or PM phenotype were observed.

Anti-SRP antibody-associated necrotizing myopathy: 2 clinical cases

Necrotizing myopathies are a subtype of autoimmune myopathies characterized by muscle fiber necrosis with minimal infiltration by inflammatory cells on muscle biopsy. This group of myopathies is defined by flaccid palsies due to prima‑ ry skeletal muscle damage as well as extramuscular manifestations such as fever, rash, arthritis, Raynaud’s syndrome and interstitial lung disease. The presence of anti-SRP antibodies is associated with rapidly progressive refractory myositis predominantly affecting limb muscles and axial muscles.Objective of the work is to analyze the course of severe, refractory to several lines of immunosuppressive therapies anti-SRP associated necrotizing myopathy and to highlight an adequate treatment regime.Necrotizing myopathy was suspected in patients aged 39 and 56 years with rapidly progressive flaccid tetraparesis on the basis of clinical and anamnestic data, the results of needle electromyography and muscle magnetic resonance imaging, as well as the analysis of myositis-specific and myositis-associated autoantibodies. In both cases, a rapid development of atrophies, marked muscle weakness in the limbs, without involvement of the bulbar musculature, was observed. To achieve effective control of the disease progression, several lines of therapy were required: glucocorticosteroids, intravenous immunoglobulins, methotrexate and rituximab. Our observations are consistent with those in the literature.Our observations illustrate the clinical course of severe myopathy associated with anti-SRP antibodies. Early initiation of aggressive immunosuppression is crucial to control the disease progression. Treatment and rehabilitation allow achieving significant improvement of the patient’s condition.

Biological Therapies in Inflammatory Myopathies.

Idiopathic inflammatory myopathies (IIM) are a rare group of disorders that feature progressive immune-mediated skeletal muscle destruction along with skin, lung, and joint involvement. Management of IIMs necessitates glucocorticoid therapy followed by conventional steroid-sparing agents to control disease activity. In the settings of refractory myositis or life-threatening manifestations, e.g. lung involvement or oropharyngeal dysphagia, second-line therapies are needed to minimize disease burden, avoid end-organ damage and steroid toxicity, and decrease mortality. These therapies may include biological disease-modifying antirheumatic drugs (bDMARDs), and to a lesser extent, targeted synthetic disease-modifying antirheumatic drugs (TSD). This article reviews the current use of bDMARDs, e.g. intravenous immunoglobulin and rituximab, and a TSD-Janus kinase inhibitors (JAKI)-along with their indications, efficacy, and safety in managing IIM.

Efficacy and safety of rituximab treatment in patients with idiopathic inflammatory myopathies: A systematic review and meta-analysis.

Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of autoimmune diseases with various subtypes, myositis-specific antibodies, and affect multiple systems. The treatment of IIMs remains challenging, especially for refractory myositis. In addition to steroids and traditional immunosuppressants, rituximab (RTX), a B cell-depleting monoclonal antibody, is emerging as an alternative treatment for refractory myositis. However, the therapeutic response to RTX remains controversial. This meta-analysis aimed to systematically evaluate the efficacy and safety of RTX in patients with IIMs, excluding sporadic inclusion body myositis. PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, and WanFang Data were searched for relevant studies. The overall effective rate, complete response rate, and partial response rate were calculated to assess the efficacy of RTX. The incidences of adverse events, infection, severe adverse events, severe infection, and infusion reactions were collected to evaluate the safety of RTX. Subgroup analyses were performed using IIM subtypes, affected organs, continents, and countries. We also performed a sensitivity analysis to identify the sources of heterogeneity. A total of 26 studies were included in the quantitative analysis, which showed that 65% (95% confidence interval [CI]: 54%, 75%) of patients with IIMs responded to RTX, 45% (95% CI: 22%, 70%) of patients achieved a complete response, and 39% (95% CI: 26%, 53%) achieved a partial response. Subgroup analyses indicated that the overall efficacy rates in patients with refractory IIMs, dermatomyositis and polymyositis, as well as anti-synthetase syndrome were 62%, 68%, and 62%, respectively. The overall efficacy rates for muscle, lungs, and skin involvement were 59%, 65%, and 81%, respectively. In addition, studies conducted in Germany and the United States showed that patients with IIMs had an excellent response to RTX, with an effective rate of 90% and 77%, respectively. The incidence of severe adverse events and infections was 8% and 2%, respectively. RTX may be an effective and relatively safe treatment choice in patients with IIMs, especially for refractory cases. However, further verification via randomized controlled trials is warranted.

A novel estrogen receptor 1-sphingomyelin phosphodiesterase acid like 3B pathway mediates rituximab response in myositis patients.

The B cell depleting biologic, rituximab, is used to treat refractory autoimmune myositis. However, the beneficial effects of rituximab appear to outweigh the known contribution of B-cells in myositis. We aimed to elucidate how myositis patients respond differently to rituximab and possible alternative mechanisms of action. Here we have: a) comprehensively investigated concurrent mRNA and microRNA expression in muscle biopsies taken at baseline and 16 weeks post treatment in ten patients who were part of the rituximab in myositis (RIM) trial; and b) investigated the beneficial effect of rituximab on myositis muscle cells. Our analyses identified an increased number of changes in gene expression in biopsies from patients who had a clinical response to rituximab (n = 5) compared with non-responders (n = 5). The two groups had completely different changes in microRNA and mRNA expression following rituximab therapy, with the exception of one mRNA, BHMT2. Networks of mRNA and microRNA with opposite direction of expression changes highlighted ESR1 as upregulated in responders. We confirmed ESR1 upregulation upon rituximab treatment of immortalized myotubes and primary human dermatomyositis muscle cells in vitro, demonstrating a direct effect of rituximab on muscle cells. Notably, despite showing a response to rituximab, human dermatomyositis primary muscle cells did not express the rituximab target, CD20. However, these cells expressed a possible alternative target of rituximab, sphingomyelinase-like phosphodiesterase 3 b (SMPDL3B). In addition to B cell depletion, rituximab may be beneficial in myositis due to increased ESR1 signalling mediated by rituximab binding to SMPDL3B on skeletal muscle cells.

Low-dose rituximab is efficacious in refractory idiopathic inflammatory myopathies.

Rituximab (RTX) use early in the course of refractory idiopathic inflammatory myopathy (IIM) is not well studied. This study sought to determine the short-term efficacy of RTX in a registry-based cohort of refractory IIM. Registry-based observational data about IIM patients receiving RTX between 2018 and 2021 were included. Total improvement score was calculated from the core set measures as per International Myositis Assessment and Clinical Studies group (IMACS) at baseline, 6 months and 12 months of follow-up. Forty-two patients (F:M, 29:13), with a mean (s.d.) age of 39.5 (11.5) years were studied. Majority of patients received RTX for refractory myositis, after a median (interquartile range) duration of 8 (4,18) months. Twenty-eight received RTX at a dosage of 1 g × two doses, while 14 received 500 mg × two doses with an interval of 15 days. At 6 months and 12 months post-RTX, the improvement was recorded in manual muscle testing (MMT-8) scores, physician global assessment (PGA), patient global assessment (PtGA) and median steroid dosage as compared with the baseline (P < 0.01 for all). A mean (s.d.) improvement of 44.5 (16) and 48.7 (19.2) in total improvement score was recorded at 6 and 12 months, respectively. The change in MMT-8, PGA and PtGA scores from baseline between the two dosage regimens of RTX were comparable at 6 and 12 months. Severe lower respiratory tract infections requiring hospitalization occurred in three patients of the cohort. RTX improved IMACS core set measures and had steroid sparing efficacy at 6 and 12 months in patients with IIM in this registry-based study. Rituximab as an induction regimen of two doses of 500 mg can be as efficacious as 1 g at 6 months and 12 months of follow-up.

Treatment of Dermatomyositis and Immune-Mediated Necrotizing Myopathy with Poor Muscle Recovery with Steroids and IVIg: Therapeutic Strategies for Refractory Inflammatory Myositis

The majority of inflammatory myositis cases can be cured by immunomodulatory therapies. We recently observed that the phenotype and response to therapies differed according to myositis-specific autoantibodies; therefore, it is essential to select a suitable therapy after thoroughly evaluating the autoantibody, clinical severity, and complications. In some cases, the symptoms can be controlled by steroid monotherapy, but some cases exhibit steroid resistance and require other therapies. We recommend intensive treatment involving the addition of immunosuppressive agents in the early stage and repeated intravenous administration of immunoglobulin therapy in cases of refractory myositis, such as immune-mediated necrotizing myopathy.

Efficacy of Infliximab in Disease Control of Refractory Orbital Myositis

ABSTRACT Purpose: Orbital myositis is a common cause of orbital inflammation with localized involvement of the extra ocular muscles. This study aimed to assess the value of infliximab in controlling orbital myositis and reducing its relapse rate. Methods: We conducted a retrospective review of the medical records of all consecutive patients with orbital myositis treated with infliximab between 2007 and 2016. We examined change in corticosteroid and immunomodulatory doses as well as relapse rates following treatment with infliximab. Results: The study included seven patients with an average follow up of 19 ± 13.4 months. The mean dose of systemic corticosteroid was reduced from 28.57 ± 14.35 mg/day at the time of infliximab initiation to 7.00 ± 6.83 mg/day at final follow-up (p = .003). Long-term remission was achieved in 85.7% (n = 6). Conclusion: This study supports the role of infliximab in treating refractory orbital myositis and this was associated with clinical improvement, decreasing relapse rate with dose reduction of conventional treatment.

Refractory myositis in a patient of Sjögren’s syndrome having only anti‐SS‐A (60 kDa) antibody

We present a very rare case of primary Sjögren’s syndrome with refractory myositis. She had only anti‐Ro60 antibody of anti‐SS‐A, which is extremely rare in patients with Sjögren’s syndrome and polymyositis/dermatomyositis. We suggest a possibility that not only anti‐SS‐A/Ro52 but also anti‐SS‐A/Ro60 may contribute to the resistance in the same way.

P30 A case of recurrent orbital myositis

Case report - IntroductionAn interesting case of an 11-year recurrent isolated lateral rectus myositis. Initially responsive to short courses of oral steroids; however, this has more recently become refractory and now the patient is unable to wean off steroids. The use of biologics in these patients is uncommon and there are very few case reports of this and the outcomes. We present a case of refractory orbital myositis treated with rituximab.Case report - Case descriptionA 38-year-old female presented in 2009 with ocular pain, swelling and diplopia. After review by the ophthalmology team an MRI orbits was requested which showed swelling and enhancement of the right lateral rectus muscle, consistent with orbital myositis. She had no other symptoms of myositis elsewhere, and no other symptoms suggestive of a connective tissue disease. Her ANA, ENA and extended myositis panel were negative and therefore aetiology was uncertain. She had no past medical history, but was later diagnosed with hypothyroidism with positive TPO antibodies. Throughout the 11 years since diagnosis her thyroid disease has been well controlled, and she has had normal free T3/T4 and TSH. It was felt that thyroid eye disease was unlikely to present with a single muscle. She was initially treated with a course of 40mg oral prednisolone reducing over 6 weeks and symptoms resolved. In 2013 she had her first relapse, which was treated with prednisolone reducing over the course of 12months, and again symptoms resolved. Her third relapse in 2019 was treated with steroids, but patient was unable to wean off this, requiring 60mg of prednisolone, and at this point was referred to rheumatology for steroid sparing agents. Between 2013 and 2019 there was MRI progression with volumetric enlargement of the right lateral rectus with intra-orbital space reduction.Under the care of rheumatology, she had repeat connective tissue disorders and myositis screen. She was started on azathioprine as a steroid sparing agent. This had little effect and she was still debilitated by orbital pain and diplopia, and unable to reduce her prednisolone below 30mg daily. She trialled intra-orbital steroid injections with little benefit. She has now been started on rituximab infusions to allow us to wean steroids. Thus far she has had two doses and we await the outcome from this treatment. Case report - DiscussionOrbital myositis can be a debilitating condition causing diplopia and pain, as in the case of this 38-year-old female who has been off work for the past year due to the condition. It can affect single muscles or multiple muscles and may be unilateral or bilateral. The major differential diagnosis is thyroid eye disease which would not usually cause an isolated myopathy, is usually painless and slowly progressive and as such was felt unlikely to be the underlying pathology in this case. From a literature review into idiopathic orbital inflammation, including myositis, 75% of patients are found to have a good response to corticosteroids. Second-line treatments include radiotherapy, methotrexate/azathioprine and other biologic agents. A case report in 2014 of 10 patients with orbital myositis refractory to steroids and at least one other immunosuppressant, demonstrated that rituximab was safe and effective, with 7/10 patients noting improvement of their symptoms. Out of those seven patients, four had been on steroids at induction of rituximab and all of the patients were able to reduce their steroid dose. The patients in this trial received two initial doses of rituximab and were permitted to have a further dose at 24 weeks if there were recurrence of symptoms. Four out of the seven patients required a further infusion after 24 weeks. In a review of the literature, we have noted a further two case reports of the use of rituximab in orbital myositis from 2008 and 2012 with good response. Both patients were unable to wean from corticosteroids and had tried other DMARDs such as methotrexate. Other case reports of biologics therapy include a case report of two patients in which adalimumab was used and allowed steroid reduction with good results for at least 9 months.Case report - Key learning pointsOrbital myositis should be assessed for other features of polymyositis, as well as investigated for thyroid eye diseaseMost patients will have a good response to oral corticosteroidsAround a quarter of cases can have refractory disease. In these patients there remains a management dilemma. Options include radiotherapy, disease modifying agents such as methotrexate and azathioprine, and biologic therapy such as adalimumab or rituximabThere is limited evidence in the literature as to the best treatment option and ideal length of treatment for refractory orbital myositis cases

Response to cyclophosphamide and rituximab therapy in idiopathic inflammatory myopathies: A single center experience

Aim of the workTo evaluate the clinical response to cyclophosphamide (CYC), and rituximab (RTX) following CYC regarding muscle power and creatine kinase (CK) level changes, and the ability to manage cardiac and bulbar affection in dermatomyositis (DM) and polymyositis (PM) patients. Patients and methodsTwenty two idiopathic inflammatory myopathies (IIM) patients: 14 (63.6%) DM and 8 (36.4%) PM were categorized into CYC group (n = 17) received only CYC, and RTX group received RTX following refractory CYC (n = 5). History taking and clinical examination were done, and Medical Research Council Sum Score (MRC-SS) and CK were evaluated at baseline visit, by end of monthly CYC, and 18 months after CYC or RTX. Improvement of cardiac affection or bulbar manifestations was checked. ResultsPatients were 16 females and 6 males (F:M 2.7:1) and mean age was 34.9 ± 14.9 years. The patients were followed up for 7.7 ± 4.3 years. MRC–SS increased in (CYC group) and in (RTX group) (p < 0.001, and p = 0.018 respectively). CK levels decreased significantly in CYC group (p < 0.001) but not in RTX group. MRC-SS changes in males, females, DM, PM patients were (p = 0.007, p < 0.001, p < 0.001, p = 0.006 respectively), and CK changes (p = 0.17, p < 0.001, p < 0.001, p = 0.006 respectively). The two DM cardiac patients and the three PM patients with bulbar manifestations in (RTX group) showed improvement in their extra-muscular manifestations. ConclusionCYC can be an effective drug in the treatment of IIM muscle affection. RTX may be promising for refractory myositis, cardiac and bulbar manifestations, so these patients should be a target for its early administration.

Rituximab for Inflammatory Myopathies in a Colombian Cohort.

Rituximab (RTX) is a treatment for refractory inflammatory myopathies, such as dermatomyositis (DM) and polymyositis (PM). This study describes the characteristics of patients receiving RTX for myositis in our institution to evaluate its efficacy. We collected demographic data from all patients diagnosed with DM or PM who received RTX between 2011 and 2018. Clinical and serological variables (including creatine phosphokinase [CPK] levels) were analyzed. Remission of disease was defined as no evidence of disease activity (active myositis) for longer than a 6-month continuous period while undergoing myositis therapy or no medication. Eighteen patients who had received first-line immunosuppressants were included. Fifteen (83%) had DM, 2 (11%) had PM, 1 had juvenile dermatomyositis, and 14 (77%) were women. All patients received glucocorticoids. Three patients (16.6%) were treated with RTX as monotherapy, and 15 (83.3%) were treated with RTX combined with other immunosuppressants. On average, there were 2 RTX treatment cycles. Improved muscular weakness was found in 13 cases (72%), and improved serum CPK levels were found in 15 cases (83%). Twelve patients (66%) achieved remission. Most patients experienced an objective improvement, as reflected in their serum CPK values and degree of muscular weakness. This suggests that RTX could be helpful in treating refractory myositis.

Factors associated with refractory autoimmune necrotizing myopathy with anti-signal recognition particle antibodies

BackgroundAutoimmune necrotizing myopathy with anti-signal recognition particle antibodies (ANM-SRP) is regarded as refractory myositis, whereby some patients respond poorly to conventional immunosuppression and require B cell depletion treatment. This study aimed to evaluate factors associated with refractory ANM-SRP.ResultsClinical and pathological data from 48 patients with ANM-SRP were collected. We followed up clinical symptoms and image changes over 12 months. Univariate and multivariate analyses were undertaken to determine the associations between variables of interest and poor response to therapy. Refractory ANM-SRP appeared in 32.5% of patients who showed no or minimal improvement after 12 months of steroid therapy. The clinical risk factors for refractory patients were being male (OR, 19.57; P < 0.001), severe muscle weakness (OR, 7.51; P < 0.001) and concurrent interstitial lung disease (OR, 39.70; P < 0.001). The imaging refractory-related factor was the fatty infiltration rate of thigh muscles over 3 months (P = 0.022) and the pathological factor associated with refractory ANM-SRP was the high expression of B cell activating factor receptor (BAFF-R) in muscle (P = 0.036).ConclusionBeing male, severe muscle weakness, concurrent interstitial lung disease, quick development of muscle fatty infiltration and more BAFF-R and B lymphocyte infiltration in muscle indicate a poor response to immunosuppressive therapy in patients with ANM-SRP.

A Case of Refractory Myositis

We report here a statin naive lady who had refractory myositis for years. The diagnosis was revised to be anti-HMGCR related immune mediated necrotizing myopathy after repeating the muscle biopsy and checking the autoantibody. This report serves as a diagnostic alert that anti-HMGCR related immune mediated necrotizing myopathy should be considered in refractory myositis cases even though there is no statin exposure history, as both the treatment and prognosis may differ.

Favorable rituximab response in patients with refractory idiopathic inflammatory myopathies

BackgroundInterpretation of rituximab efficacy for refractory idiopathic inflammatory myopathies (IIM) is hampered by the absence of a uniform definition of refractory myositis and clinical response. Therefore, rigorous criteria of refractoriness, together with a homogenous definition of clinical improvement, were used to evaluate rituximab one-year response.MethodsA retrospective cohort study including 43 IIM (15 antisynthetase syndrome, 16 dermatomyositis, 12 polymyositis) was conducted. All patients had refractory disease (inadequate response to at least two immunosuppressives/immunomodulatories and no less than three months sequentially or concomitantly glucocorticoid tapering) criteria. Clinical/laboratory improvement at one-year was based on modified International Myositis Assessment & Clinical Studies Group (IMACS) core set measures. The patients received two infusions of rituximab (1 g each) at baseline, followed by repeated dose after 6 months. Baseline immunosuppressive therapy was maintained and glucocorticoid dose was tapered according to clinical/laboratory parameters.ResultsFive patients had side effects at the first rituximab application and were excluded. Therefore, 38 out of 43 patients completed the one-year follow up. Almost 75% of the patients attained clinical and laboratory response after one-year. A significant reduction in median glucocorticoid dose (18.8 vs. 6.3 mg/day) was achieved and 42% patients were able to discontinue prednisone. In contrast, young individuals and patients with dysphagia had a tendency to be non-responders to rituximab. No severe infections were observed.ConclusionThis study provides convincing evidence that rituximab is an effective and safe therapy for refractory IIM.

P.075 Inflammatory Myositis associated with Myasthenia Gravis with and without thymic pathology: case series and literature review

Background: The association of myasthenia gravis (MG) and inflammatory myositis (IM) is rare and often only one of the diseases is diagnosed. Methods: In this study, we reviewed medical records of patients seen at NMDU from 2004 to 2017 who had diagnosis of concurrent MG and IM. The data is presented descriptively. -Results: We identified 7 patients with MG-IM overlap. Clinical features, laboratory and pathology data of the patients are summarized in Table 1. Conclusions: This is one of the largest case series with MG-IM overlap. It is very important to recognize such association and the different pattern of muscle involvement because therapies may be adjusted to treat both conditions. In patients with thymic pathology, conventional disease modifying agents, IVIG and glucocorticoid in addition to thymoma resection appear to be effective. In patients with refractory MG and myositis who were AChR negative, rituximab may be effective.

P.191 - Rituximab for the treatment of anti-HMGCR necrotizing autoimmune myopathy

The effectiveness of rituximab in refractory myositis has been suggested by case reports and case series. Recently, anti-HMGCR, a new autoantibody associated with necrotizing autoimmune myopathy and related to statin exposure was discovered. Our objective was to address the effectiveness of rituximab in the subgroup of anti-HMGCR necrotizing autoimmune myopathy. We identified 4 patients with anti-HMGCR necrotizing autoimmune myopathy that were treated with rituximab. Medical records were reviewed to assess their clinical presentation, muscle testing, serum CK levels, corticosteroid doses and associated immunosuppressant agents while receiving rituximab, and their evolution at last follow-up. Only one patient had previous statin exposure. Two patients had a slowly-progressive dystrophic-like presentation over 20 years. All patients had a relapsing disease and needed multiple therapy trials and combination to maintain remission. Two patients were resistant to rituximab and clearly IVIg-dependent, requiring long-term treatment with IVIg to maintain remission. One patient had a thrombotic event while on IVIg and was successfully switched to rituximab. Another patient experienced a biological flare with an isolated CK rise following IVIg discontinuation yet subsequent slowly-progressive CK lowering with rituximab re-infusion and introduction of methotrexate. At last follow-up all patients were in clinical remission. Two of them were still on IVIg with low-dose prednisone +/− azathioprine. Two patients were adequately controlled with rituximab and low-dose prednisone +/− methotrexate. Our patients with anti-HMGCR necrotizing autoimmune myopathy had a refractory disease with multiple relapses. Larger prospective trials are needed to confirm potential efficacy of rituximab in this subgroup of patients.

Rituximab in the treatment of inflammatory myopathies: a review.

Several uncontrolled studies have encouraged the use of rituximab (RTX) in patients with myositis. Unfortunately, the first placebo-phase trial to assess the efficacy of RTX in refractory myositis did not show a significant difference between the two treatment groups, and doubts have been expressed about its study design. In this review we present an up-to-date overview of the reported experiences of RTX therapy in myositis. A PubMed search was performed to find all the available cases of refractory myositis patients treated with RTX up to July 2015. The following terms were assessed: inflammatory myopathies OR anti-synthetase syndrome OR polymyositis OR dermatomyositis AND RTX. A total of 48 studies were included. We identified 458 patients with myositis treated with RTX. We found a rate of response to RTX of 78.3%. RTX can play a role in the management of patients with myositis, at least in those with positive myositis-specific autoantibodies.