The use of rituximab in idiopathic inflammatory myopathies: description of a monocentric cohort and review of the literature

Abstract

Rituximab (RTX), a chimeric monoclonal antibody targeted against CD20, has been used to treat refractory inflammatory myopathies (IIM). The primary objective of this study was to retrospectively assess the efficacy of RTX in reducing disease activity in patients with IIM refractory to conventional therapy. Secondary aim was the evaluation of adverse events (AE) during the treatment period. We examined 26 patients with a diagnosis of IIM, referred to our Rheumatology Unit and treated with RTX for active refractory disease. Patients were treated with RTX 1000 mg i.v., twice, with a 2-week interval. RTX treatment was associated with a significant reduction of creatine kinase (p=0.001) after six months compared to the baseline, an improved muscular strength measured with MMT8 (p<0.001) and a reduction of the extramuscular activity of the disease measured with MYOACT (p<0.001). In particular, RTX improved DM skin rash, arthritis and pulmonary manifestations. Autoantibody positivity (in particular antisynthetase, anti- SRP and antiRo/SSA), and a disease duration <36 months at the moment of the treatment are associated with a better response rate. Treatment with RTX was also associated with a reduction of the mean daily dose of steroids needed to control disease activity (p=0.002). Our results have confirmed that RTX is efficacious in the treatment of refractory IIM. Ad hoc controlled trials are needed to better clarify the specific subset of patients who may better respond to the treatment and the optimal therapeutic schedule.

Efficacy and Safety of Rituximab in Korean Patients with Refractory Inflammatory Myopathies

“…There were 2 patients who received RTX due to acute aggravation of organizing pneumonia, with normal serum CPK level (64 unit/dL and 79 unit/dL, respectively) and high ESR (116 mm/hr and 64 mm/hr, respectively). Unlike previous studies 42 43 which reported especially favorable responses to pulmonary involvement, the 2 patients mentioned above with organizing pneumonia did not fully recover after RTX treatment, and they did not achieve CPK reduction nor by their physician's opinion. Contrarily, one patient with generalized and refractory skin lesions with normal serum CPK (32 unit/dL), CRP (0.15 mg/dL) and ESR levels (18 mm/hr) had almost fully recovered after RTX treatment and was classified as a responder.…”

Myopathy in a 61-year-old Hispanic man

“…Although such a strategy has not been evaluated by randomised trials, several case reports and case series suggest that rituximab is an effective therapy for anti-SRP autoantibody associated IMNM, while IVIG has been quite successful in treating anti-HMGCR IMNM 16 17. This highlights the importance of serology in diagnosing patients with inflammatory myositis 15 18…”

On- and off-label use of rituximab in rheumatic diseases

“…99,100,102 Skin manifestations of patients with dermato-polymyositis would be sensitive to RTX only in some cases or not at all. [103][104][105][106] Dysphagia essentially proves unresponsive to RTX. 107 In short, off-label RTX therapy can be useful in several patients affected by refractory myositis.…”