SAT0529 Short-term efficacy and safety of biosimilar rituximab in patients with systemic vasculitides

Objectives To study efficacy and safety of biosimilar (intended copy) rituximab (Acellbia, BIOCAD) in patients with systemic vasculitides. Methods We enrolled in our case series all consecutive patients with systemic vasculitides diagnosed according to CHCC2012 and ACR criteria (if applicable) who were treated with biosimilar rituximab since 2015. Activity of vasculitis was evaluated using BVAS3. CD19+ B-cells count was measured by standard method. Patients received intravenous rituximab at a 500 mg dose (four weekly infusions for remission induction or two weekly every 6 months infusions for maintenance treatment). Results In total, 45 patients were treated with biosimilar rituximab (29 GPA, 12 MPA, 1 EGPA, 2 cryoglobulemic vasculitis, 1 rheumatoid vasculitis). In 12 patients (7 GPA, 3 MPA, 1 CryoVas, 1 RheumVas), rituximab was administered for induction of remission due to high activity and relapsing course of vasculitis and low efficacy of previous treatment. 33 patients (22 GPA, 9 MPA, 1 EGPA, 1 CryoVas) received rituximab for maintenance of remission. Median duration of follow-up was 12 months. 6–26 At 1 and 3 months, all patients achieved B-cell depletion. At 6 months, B-cell repopulation was shown in 9 patients (20%). Remission induction therapy with rituximab resulted in decrease of median BVAS from 16 10–24 to 1 (0–4) at 3 months and to 0 (0–2) at 6 months. At 3 and 6 months, median prednisone dose was tapered from 50 mg 35–80 to 25 mg 15–40 and 10 mg, 5–20 respectively. In patients who received rituximab for maintenance treatment, median BVAS showed no disease activity (0–1) both at baseline and at 3 or 6 months. At baseline and at 3 months median doses of prednisolone were 5 mg (0–7.5) and 5 mg (0–5). At 6 months, it was reduced to 2.5 mg (0–5). Biosimilar rituximab had acceptable safety profile. Adverse events included mild infusion reaction, 2 urinary 3 and bronchopulmonary 5 infections which required intravenous antibiotics (median 4 months after infusions), hypogammaglobulinemia 2 that persisted for at least 12 months and 1 case of late-onset neutropenia in 8 months. Conclusions Biosimilar rituximab showed high efficacy and acceptable safety in patients with systemic vasculitides. Disclosure of Interest None declared