Merkel PA, Niles JL, Mertz LE, et al. - Researchers performed a Phase IV, open‐label, prospective study to define 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 United States. They assessed patients initiating treatment with rituximab every 6 months for up to 4 years.  This study included a total of 97 patients (72 with GPA and 25 with MPA) to receive rituximab through a median of 8 (range, 1‐28) infusions, and were followed up for a median of 3.94 (range, 0.05‐4.32) years. The outcomes demonstrate that in patients with GPA or MPA, the safety profile of long‐term treatment with rituximab was consistent with that of rituximab administered for shorter durations and with rituximab’s known safety profile in other autoimmune disease for which it has received regulatory approval. These data serve clinicians with long‐term, practice‐level safety data for rituximab in the treatment of GPA or MPA.