A Retrospective Study of Clinical Efficacy of Rituximab in Pemphigus Patients

Abstract

Background: Pemphigus comprises a group of potentially life-threatening autoimmune blistering disorders caused by autoantibodies directed against desmoglein proteins. Although systemic corticosteroids remain the traditional first-line therapy, rituximab, an anti-CD20 monoclonal antibody, has emerged as a highly effective B-cell-depleting agent used as a steroid-sparing adjunct in refractory disease and, increasingly, earlier in the disease course. However, real-world experience with rituximab in Indian tertiary-care settings remains limited. Objectives: This study evaluated the clinical efficacy and safety of rituximab in patients with pemphigus vulgaris (PV) and pemphigus foliaceus (PF) who were treated at a tertiary-care institution in western India. Methods: This retrospective observational study reviewed the medical records of 30 patients with pemphigus, confirmed clinically and by skin biopsy, with a Tzanck smear performed according to institutional protocol, who received rituximab in the Department of Dermatology from September 2022 to November 2024. Direct immunofluorescence and desmoglein ELISA were not routinely available at our centre and were not used as diagnostic prerequisites; this is acknowledged as a limitation. All patients had previously received systemic corticosteroids; therefore, rituximab was used as a steroid-sparing, second-line agent. Both recently diagnosed patients and those with longer-standing relapsed or refractory disease were included. Rituximab was administered according to the rheumatoid arthritis protocol (1 g × 2 infusions), the lymphoma protocol (375 mg/m2 weekly × 4), or via the intralesional route, with selection guided by physician judgement, disease severity, and cost or affordability. Disease control, complete remission (CR) on or off therapy, and relapse were defined using the International Pemphigus Committee consensus criteria. Outcomes were analysed descriptively, with 95% confidence intervals (Wilson method) and a post hoc Fisher exact test for the principal PV-versus-PF comparison. Results: The cohort comprised 24 patients with PV (80%) and 6 with PF (20%); the mean age was 44.8 ± 12.6 years, and 60% were female. At the final documented assessment, 26 patients (86.7%, 95% CI 70.3 - 94.7%) were in complete remission, including 14 (46.7%) off all therapy and 12 (40.0%) on minimal therapy. Four patients (13.3%, 95% CI 5.3 - 29.7%) were in relapse after having previously achieved complete remission. No patient was a non-responder. Three of the four relapsing patients had PF (relapse rate, 50.0% in PF vs 4.2% in PV; Fisher exact P = 0.018). Rituximab was well tolerated: 96.7% reported no adverse effects, 1 patient developed a transient hepatic enzyme elevation, and no serious infections, hypogammaglobulinaemia, or progressive multifocal leucoencephalopathy occurred. Conclusions: Rituximab achieved a high final complete remission rate with a favourable safety profile in this real-world cohort, supporting its role as an effective steroid-sparing agent in pemphigus. The significantly higher relapse rate observed in PF warrants closer long-term monitoring and a lower threshold for maintenance or booster dosing in this subgroup.