Objectives. To assess the efficacy and safety of rituximab (RTX) in patients with refractory idiopathic inflammatory myopathies (IIMs).
Methods. RTX efficacy was based on improvement in three criteria: creatine phosphokinase (CPK) level, daily CS dose and physicians’ opinion. A decrease in CPK level or CS dose was significant if it was >25%.
Results. Thirty patients were studied (21 women; age 52.5 years, disease duration 6.1 years). All had previously received immunosuppressors (ISs). Twenty-five patients received 1 g of RTX twice 2 weeks apart and five received 4 weekly RTX infusions (375 mg/m2). RTX was given in association with IS in 21 patients. Twenty-eight patients received CS (mean dose 21.2 mg/day). Mean follow-up was 17.2 months. Thirteen adverse events were reported, including seven infections and one serious infection (pyelonephritis). RTX was effective in 16 patients. Duration of efficacy was 15.5 months. Of the 20 patients with baseline CPK level ≥2 × upper limit of normal (ULN), 11 (55%) improved. The main level fell from 20.7 to 11 × ULN. CS decreased in 15 patients, stopped in 4, remained stable in 8 and increased in the remaining 3. The CS dose decreased from 21.2 to 9.9 mg/day. The physicians’ opinion was favourable in 21 patients. Manual muscle testing was performed in only five patients: it increased from 87 to 91/100 at 6 months.
Conclusions. RTX was well tolerated and had some beneficial effects on patients with IIM, the main limitation of this study resulted in a lack of manual muscle testing.