Clinical and Immunological Outcomes of Rituximab Therapy in Pemphigus: A Prospective Observational Study

Introduction: Pemphigus is a rare group of autoimmune blistering diseases, most often mediated by IgG autoantibodies but occasionally involving IgA or other immunoglobulin classes, characterized by the loss of epidermal cell adhesion due to desmoglein-targeted autoantibodies. Rituximab, an anti-CD20 monoclonal antibody, has emerged as a novel and effective treatment, offering targeted B-cell depletion.

A prospective observational study was conducted on 51 patients with confirmed pemphigus. Patients received either the RA protocol (1 g rituximab 2 weeks apart) or the lymphoma protocol (375 mg/m2 weekly for 4 weeks). Disease stages were defined according to the international consensus on pemphigus [Murrell et al., J Am Acad Dermatol. 2008;58(6):1043-6]. Desmoglein 1 and 3 levels were measured using ELISA at baseline and at 6 months. Patients receiving DCP therapy were analyzed separately but excluded from primary rituximab remission analysis. Clinical remission, relapse, and adverse events were recorded.

Most patients (70.59%) were diagnosed with pemphigus vulgaris, and 72.55% achieved complete remission. Mean Dsg1 levels significantly reduced from 211.96 ± 109.10 to 10.95 ± 25.43 and Dsg3 from 206.08 ± 105.11 to 17.69 ± 47.79 (p < 0.001). Patients receiving the RA protocol demonstrated a slightly greater reduction in Dsg3 titers compared to the lymphoma group, though not statistically significant. Recalcitrant disease was noted in 21.57% of cases. The low RA protocol was the most commonly used (70.59%). Adverse events were minimal and included mild infusion reactions. Mortality was reported in 5.88% of cases.

Rituximab therapy demonstrates robust clinical and immunological efficacy in pemphigus, with substantial reductions in Dsg1 and Dsg3 antibody levels and high remission rates. Its use, particularly with the low RA protocol, offers a safer and more effective alternative to conventional immunosuppressive regimens. Patients on DCP therapy had slower antibody decline and greater treatment toxicity compared to rituximab, reaffirming rituximab's superiority.