Rituximab therapy for intractable pemphigus: A multicenter, open-label, single-arm, prospective study of 20 Japanese patients

This was a multicenter clinical trial of rituximab, a chimeric monoclonal IgG antibody directed against CD20, for the treatment of refractory pemphigus vulgaris and pemphigus foliaceus. In total, 20 patients were treated with two doses of rituximab (1000 mg; 2 weeks apart) on days 0 and 14. The primary end point was the proportion of patients who achieved complete or partial remission on day 168 following the first rituximab dose. Of the 20 enrolled patients, 11 (55%) and four (20%) achieved complete and partial remission, respectively; therefore, remission was achieved in a total of 15 patients (75.0% [95% confidence interval, 50.9%-91.3%]). It was demonstrated that the remission rate was greater than the prespecified threshold (5%). In addition, a significant improvement in clinical score (Pemphigus Disease Area Index) and decrease in serum anti-desmoglein antibody level were observed over time. Four serious adverse events (heart failure, pneumonia, radial fracture, and osteonecrosis) were recorded in two patients, of which only pneumonia was considered causally related with rituximab. The level of peripheral blood CD19-positive B lymphocytes was decreased on day 28 after rituximab treatment and remained low throughout the study period until day 168. Our results confirm the efficacy and safety of rituximab therapy for refractory pemphigus in Japanese patients.

[Clinical Analysis of Eight Cases of Pemphigus with High Titers of Anti-desmoglein Antibodies in Remission]

Objective To investigate the clinical manifestations,diagnosis,treatment,and laboratory examination characteristics of 8 pemphigus patients with high titers of anti-desmoglein antibodies in remission. Methods A retrospective study was conducted for the pemphigus patients diagnosed and treated in the department of dermatology from January 2013 to September 2020.The patients should have the serum anti-desmoglein antibodies ≥150 U/ml in remission or the antibody levels dropped less than 20%(calculated based on the maximum detection limit of 150 U/ml)of their initial ones detected before treatment,and the clinical and laboratory data of patients eligible for the inclusion criteria were collected. Results Among the 134 pemphigus patients with available follow-up data during this period,a total of 8 patients met the criteria,with the follow-up period of 21-85 months and the remission duration of 18-70 months.They all received less than or equal to 10 mg/d prednisone and had high titers of anti-desmoglein antibodies.At their first visit,the number of patients with positive anti-desmoglein 1/desmoglein 3 antibodies was 7.Two patients still had high titers of anti-desmoglein 1 antibodies 19 months and 21 months after they achieved remission,and 5 patients had high titers of anti-desmoglein 3 antibodies in 18-70 months.There was one patient showing high titers of both antibodies,especially for anti-desmoglein 1 antibodies.This patient relapsed after 19 months' remission while other patients were still in clinical remission. Conclusions Some pemphigus patients showed persistent high titers of anti-desmoglein antibodies in remission.Anti-desmoglein 3 antibodies were more common to keep positive,while high titer of anti-desmoglein 1 antibodies was less observed.The high titer of anti-desmoglein 1 antibodies had a correlation with recurrence.For the pemphigus patients with long-term clinical remission but high antibody titer,the dosages of corticosteroids should be adjusted carefully according to their actual clinical manifestations and the positive antibody type.For the patients with high titer of anti-desmoglein 1 antibodies,the dosage reduction of corticosteroids should be appropriately slower.

Anti-Thyroid Peroxidase Reactivity Is Heightened in Pemphigus Vulgaris and Is Driven by Human Leukocyte Antigen Status and the Absence of Desmoglein Reactivity

Pemphigus vulgaris (PV) belongs to an autoimmune disease cluster that includes autoimmune thyroid disease (AITD), suggesting common mechanisms driving autoimmune susceptibility. Our group has shown that PV patients exhibit significant reactivity to AITD-related anti-thyroid peroxidase (anti-TPO), and anti-TPO antibodies affect signaling pathways in keratinocytes similar to anti-desmoglein (Dsg) 3 antibodies. To further assess the relevance of anti-TPO reactivity in PV, we analyzed anti-TPO levels in 280 PV and 167 healthy control serum samples across a comprehensive set of variable and static parameters of disease activity and etiopathogenesis. PV patients have significantly higher activity rates (A.R.s) for anti-TPO than healthy controls, but levels do not differ between phases of clinical activity and remission. Patients that carry both the PV-associated human leukocyte antigen (HLA) alleles DRB1*0402 and DQB1*0503, or DQB1*0503 alone show a low prevalence of anti-TPO (A.R. 9.5 and 4.8%, respectively), while patients that lack expression of these alleles or carry DRB1*0402 alone have a much higher prevalence of anti-TPO (A.R. 23.1 and 15.8%, respectively), suggesting that the absence of DQB1*0503 may predispose patients to the development of anti-TPO antibodies. Similarly, anti-Dsg1⁻/3⁻ patients have a higher anti-TPO A.R. (26.9%) than anti-Dsg1⁻/3⁺ (18.8%), anti-Dsg1⁺/3⁻ (14.3%), and anti-Dsg1⁺/3⁺ (3.9%) patients. Our data suggest that anti-TPO reactivity in PV is driven by genetic markers that may be in linkage disequilibrium with the established PV-susceptibility alleles and that this association drives the selection of a combination of anti-Dsg and anti-TPO antibodies, with anti-TPO filling the gap in active patients that do not carry the established PV-associated autoantibodies and/or are lacking the established PV-HLA-susceptibility alleles.