Lower doses of rituximab in remission induction for refractory granulomatosis with polyangiitis.

INTRODUCTION: Recently, rituximab (RTX)--monoclonal antibody against the CD20 molecule on the surface of B-lymphocytes is used in the treatment of antineutrophil cytoplasmic antibody (ANCA) associated vasculitides. Efficacy of the drug administered in so-called lymphoma treatment protocol (4 x 375 mg/m2/week) has been shown not to be inferior to cyclophosphamide. However, some data published lately suggest that rituximab could also be effective in much lower doses, which could lead to reducing side effects, but above all, the cost of the therapy. OBJECTIVES: Analysis of efficacy of lower doses of rituximab in remission induction in GPA patients. PATIENTS AND METHODS: We retrospectively analyzed the course, the efficacy and safety of rituximab administered at a dose lower than average in lymphoma treatment protocol (median = 1.0 g). The drug was used only in patients who presented resistance to the standard treatment with cyclophosphamide, or in whom such treatment was impossible. Disease activity was evaluated using Birmingham Vasculitis Activity Score and disease remission was defined as score 0. RESULTS: Out of the twelve patients who received RTX induction doses (period 07. 2009-07.2014), remission was achieved in the eleven (92%). Averaged observation period was 7.5 months (median). The total B-cell depletion was observed in all treated with induction scheme. During further follow-up, disease relapse in 2 patients was observed. One patient achieved remission again after re use of rituximab. The second patient died in the course of diffuse alveolar hemorrhage. In these patients, recurrence was observed respectively after 42 and 56 months of follow-up. CONCLUSIONS: The efficacy of lower doses of rituximab for the induction of remission in refractory granulomatosis with polyangiitis was confirmed. Ava- ilability of the drug in the treatment of primary vasculitis is currently limited mainly due to economic issues.