Low-dose rituximab is effective in pemphigus.

Abstract

Rituximab, an anti-CD20 antibody, was shown in open series studies to be effective in treating pemphigus at a dose of 4 × 375 mgm(-2) as approved for B-cell malignancies. We investigated whether a lower dose of rituximab is also effective for pemphigus. Patients with pemphigus were treated with a single course of two infusions of rituximab (500 mg each) at an interval of 2 weeks. Clinical consensus late end points, B-cell number, desmoglein 1 and desmoglein 3 indices were monitored. We enrolled 15 patients in the study: three with pemphigus foliaceus (PF) and 12 with pemphigus vulgaris (PV). The follow-up was 32-152 weeks (median 94). All 15 patients responded to therapy. Eight patients achieved complete remission in a median period of 5 weeks (four on minimal therapy, four off therapy). Seven patients achieved partial remission in a median period of 34·5 weeks (five on minimal therapy, two off therapy). Relapses (40%) were seen between 53 and 103 weeks (median 97) after start of therapy. B-cell numbers dropped to <1% after first infusion, and remained undetectable in patients with sustained remission. The antidesmoglein 1 index correlated well with the clinical severity in PF, but this was less obvious in PV. A low dose of rituximab is an effective and safe treatment for pemphigus. Relapses may occur, mostly at the end of the second year. Cost-effectiveness studies with a long follow-up are required to determine the proper dosage of this expensive drug in pemphigus.