Rituximab may induce extended remission in patients with granulomatosis with polyangiitis

This retrospective case series published in December in Ophthalmology examines the long-term outcomes of refractory granulomatosis with polyangiitis (GPA; formerly known as Wegener's granulomatosis) treated with rituximab. The authors found that it induced remission in all 20 patients within six months, although one-third of them relapsed within 18 months, which appeared to be predictable by rising anti-PR3 titers. However, retreatment with rituximab was effective in these patients.

The study included consecutive patients seen at a tertiary referral center. They received two doses of an intravenous infusion of 1 g rituximab administered two weeks apart.

Their median time to remission was two months (range, one to six months). Seven patients (35 percent) relapsed at a median of 13 months (range, 9 to 18 months). Five of these patients took a second course of rituximab; all of them achieved remission without further relapse.

Among the 16 patients with positive anti–proteinase-3 (PR3) titers at baseline, rising anti-PR3 titers was a statistically significant predictor of relapse. In the four patients with positive anti–PR3 antibody titers at baseline who relapsed, the anti-PR3 antibody titer rose some months before the relapse developed in all cases. This was significantly less common among patients with positive anti–PR3 who did not relapse, with only two of nine patients demonstrating a rise above baseline. The authors say this finding suggests that in patients with GPA, serum anti-PR3 titers may be sensitive enough to guide the timing of retreatment.

There were four severe adverse events during the study, of which one was directly attributed to treatment with rituximab. This patient developed Pseudomonas pneumonia within three months of his first course of treatment and within 12 months of his second course.

The authors say the study’s results confirm their earlier findings of the efficacy of rituximab in these patients and the frequently delayed onset of disease remission. They conclude that in patients with GPA, rituximab may be capable of inducing extended remission, in contrast with other biologic and conventional treatments in common use.