Clinical impact and a prognostic marker of early rituximab treatment after rituximab reimbursement in Korean pemphigus patients

Pemphigus is an autoimmune mucocutaneous blistering disease caused by autoantibodies against desmogleins. Rituximab effectively treats pemphigus by inducing remission and rapidly reducing corticosteroid dosage. In Korea, the high cost of rituximab had been a burden until the National Health Insurance began to cover 90% of rituximab costs via reimbursement for severe pemphigus patients. We analyzed 214 patients with pemphigus who were treated with their first round of rituximab. The time to initiate rituximab and the time to partial remission under minimal therapy (PRMT) were both significantly shorter after the rituximab reimbursement policy. The total steroid intake for PRMT and complete remission (CR) was less in patients who were diagnosed after the reimbursement. The interrupted time series (ITS) model, a novel analysis method to evaluate the effects of an intervention, showed a decrease in total systemic corticosteroid intake until PRMT after reimbursement began. In peripheral blood mononuclear cells from patients with pemphigus vulgaris, the relative frequencies of desmoglein 3-specific CD11c⁺CD27⁻IgD⁻ atypical memory B cells positively correlated with the periods from disease onset to rituximab treatment and to PRMT and the total systemic corticosteroid intake until PRMT. We found that early rituximab therapy, induced by the reimbursement policy, shortened the disease course and reduced the total corticosteroid use by pemphigus patients. The decreased frequency of circulating desmoglein-specific atypical memory B cells can be used as a surrogate marker for a good prognosis after rituximab.