Long-Term Safety of Rituximab in Granulomatosis With Polyangiitis and in Microscopic Polyangiitis

Objective The present study was undertaken to conduct a phase IV, open-label, prospective study to characterize the long-term safety of rituximab in a 4-year observational registry of adult patients with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) within the US. Methods Patients initiating treatment with rituximab were evaluated every 6 months for up to 4 years. Outcomes included the incidence of serious adverse events (SAEs), infusion-related reactions (IRRs), and SAEs of specific interest, including serious infections, serious cardiac events, serious vascular events, and malignancies. Results Overall, 97 patients (72 with GPA and 25 with MPA) received rituximab through a median of 8 (range 1-28) infusions and were followed up for a median of 3.94 years (range 0.05-4.32 years). The estimated incidence rates (95% confidence interval [95% CI]) of serious infections, serious cardiac events, and serious vascular events were 7.11 (4.55-10.58), 5.03 (2.93-8.06), and 2.37 (1.02-4.67) per 100 patient-years (PYs), respectively. No IRRs or SAEs occurred within 24 hours of an infusion of rituximab. None of the 9 deaths reported (crude mortality rate 2.67 [95% CI 1.22-5.06] per 100 PYs) were considered to be related to use of rituximab. Conclusion The safety profile of long-term treatment with rituximab in patients with GPA or MPA was consistent with that of rituximab administered for shorter durations and with rituximab's known safety profile in other autoimmune diseases for which it has received regulatory approval. These findings provide clinicians with long-term, practice-level safety data for rituximab in the treatment of GPA or MPA.