Current treatments and developments in pemphigoid diseases as paradigm diseases for autoantibody-driven, organ-specific autoimmune diseases

Evaluation of Nomacopan for Treatment of Bullous Pemphigoid: A Phase 2a Nonrandomized Controlled Trial

Importance

Bullous pemphigoid is a difficult-to-treat autoimmune blistering skin disease that predominantly affects older adults and is associated with an increased mortality rate.

Objective

To examine the safety and therapeutic potential of nomacopan, an inhibitor of leukotriene B4 and complement C5, in patients with bullous pemphigoid.

Design, Setting, and Participants

This multicenter, single-group, phase 2a nonrandomized controlled trial was conducted in the dermatology departments of universities in the Netherlands and Germany. Participants were enrolled between September 2018 and April 2020. Older adult patients (aged ≥55 years) with mild to moderate, new-onset or relapsing bullous pemphigoid were recruited into the study.

Interventions

Patients received nomacopan, 90 mg, subcutaneously on day 1 and 30 mg subcutaneously daily until day 42.

Main Outcomes and Measures

The primary end point was the proportion of patients with grade 3 to 5 (severe) adverse events associated or possibly associated with nomacopan. Secondary end points included mean absolute and percentage changes in the Bullous Pemphigoid Disease Area Index (BPDAI) activity score, the BPDAI pruritus score, and the patient-reported outcome measures Dermatology Life Quality Index (DLQI) and Treatment of Autoimmune Bullous Disease Quality of Life (TABQOL).

Results

A total of 9 patients (median [range] age, 75 [55-85] years) with bullous pemphigoid were included in the trial, of whom 5 were women (55.6%). No serious adverse events associated with nomacopan were found. The mean (90% CI) BPDAI activity score decreased from 32.0 (8.7) points on day 1 to 19.6 (9.0) points on day 42. Seven of 9 patients (77.8%) responded to nomacopan with a reduction in the BPDAI activity score of at least 8 points between days 1 and 42; in 3 responders, the reduction was 80% or greater. On day 42, the mean (90% CI) BPDAI pruritus score had decreased by 6.8 (4.6) points from 17.6 (4.0) points on day 1. The mean (90% CI) DLQI score decreased from 11.3 (4.2) points at baseline to 6.4 (3.8) points by day 42, and the mean (90% CI) TABQOL score decreased from 14.6 (5.4) points at baseline to 10.3 (5.0) points on day 42.

Conclusions and Relevance

Results of this nonrandomized controlled trial suggest that nomacopan can be well tolerated in older patients with bullous pemphigoid and may have therapeutic benefits for suppressing acute flares of this disease. A larger, placebo-controlled randomized clinical trial is warranted to confirm this safety profile and to establish nomacopan as a new therapeutic option for bullous pemphigoid.

Trial Registration

ClinicalTrials.gov Identifier: NCT04035733.

Bullous Autoimmune Dermatoses

BACKGROUND

Bullous autoimmune dermatoses are a clinically and immunopatho - logically heterogeneous group of diseases, characterized clinically by blisters or erosions of the skin and/or mucous membranes. In Germany, their prevalence is approximately 40 000 cases nationwide, and their incidence approximately 20 new cases per million people per year.

METHODS

This review is based on publications that were retrieved by a selective search of the literature focusing on the current German and European guidelines.

RESULTS

Recent years have seen the publication of guidelines, controlled prospective clinical trials, and multicenter diagnostic studies improving both diagnosis and therapy. Specific monovalent and multivariate serological test systems and pattern analysis of tissue-bound autoantibodies allow identification of the target antigens in 80-90% of patients. This enables the precise classification of disease entities, with implications for treatment selection and disease outcome. In 2019, the anti-CD20 antibody rituximab was approved by the European Medicines Agency for the treatment of moderate and severe pemphigus vulgaris, with an ensuing marked improvement in the care of the affected patients. To treat mild and moderate bullous pemphigoid, topical clobetasol proprionate is recommended, in severe disease, combined with systemic treatment, i.e. usually (a) prednisolone p.o. at an initial dose of 0.5mg/kg/d , (b) an immunomodulant, e.g. dapsone or doxycycline, or (c) prednisolone plus an immunomodulant.

CONCLUSION

The early recognition and precise diagnostic evaluation of bullous autoimmune dermatoses now enables improved, often interdisciplinary treatment, in accordance with the available guidelines. Current research projects are focused on new treatment approaches, an improved understanding of the underlying pathophysiology, and further refinements of diagnostic techniques.

Rituximab Followed by Belimumab Controls Severe Lupus Nephritis and Bullous Pemphigoid in Systemic Lupus Erythematosus Refractory to Several Combination Therapies

Systemic lupus erythematosus (SLE) and bullous pemphigoid (BP) are chronic autoimmune diseases in which B cells play an important pathogenic role in the different stages of the disease. B cell-targeted therapies have been suggested as a new rational approach for treating SLE. Rituximab (RTX), an anti-CD20 chimeric monoclonal antibody, failed to achieve primary endpoints in two clinical trials (EXPLORER and LUNAR) despite multiple observational and retrospective studies showing its beneficial effect on SLE. Moreover, RTX is recommended in cases of BP that is unresponsive to conventional treatments. Belimumab (BLM), a human immunoglobulin G1 λ monoclonal antibody that inhibits soluble B-lymphocyte stimulator (BlyS)/B-cell activating factor (BAFF), is the only biological treatment approved for standard therapy of refractory autoantibody-positive active SLE. Animal models and a few case reports have supported the efficacy of the combined use of RTX followed by BLM as maintenance therapy in severe lupus nephritis (LN), suggesting that their combined use may be more effective than their single use, without compromising safety. In this study, we describe the clinical case of a SLE patient with predominant renal involvement in overlap with BP, refractory to conventional therapy including RTX alone, achieving significant steroid sparing and clinical remission under sequential treatment of RTX-BLM. Moreover, we describe the first case of BP successfully treated with BLM. This case report may encourage further clinical research studies in B lymphocyte targeted combination therapy in patients affected by SLE with major organ involvement or with refractory disease, suggesting that RTX and BLM sequential therapy may be a valid option for the treatment of SLE manifestations, including conventional therapy and RTX-resistant LN.

The critical role of C5a as an initiator of neutrophil-mediated autoimmune inflammation of the joint and skin

The deposition of IgG autoantibodies in peripheral tissues and the subsequent activation of the complement system, which leads to the accumulation of the anaphylatoxin C5a in these tissues, is a common hallmark of diverse autoimmune diseases, including rheumatoid arthritis (RA) and pemphigoid diseases (PDs). C5a is a potent chemoattractant for granulocytes and mice deficient in its precursor C5 or its receptor C5aR1 are resistant to granulocyte recruitment and, consequently, to tissue inflammation in several models of autoimmune diseases. However, the mechanism whereby C5a/C5aR regulates granulocyte recruitment in these diseases has remained elusive. Mechanistic studies over the past five years into the role of C5a/C5aR1 in the K/BxN serum arthritis mouse model have provided novel insights into the mechanisms C5a/C5aR1 engages to initiate granulocyte recruitment into the joint. It is now established that the critical actions of C5a/C5aR1 do not proceed in the joint itself, but on the luminal endothelial surface of the joint vasculature, where C5a/C5aR1 mediate the arrest of neutrophils on the endothelium by activating β₂ integrin. Then, C5a/C5aR1 induces the release of leukotriene B₄ (LTB₄) from the arrested neutrophils. The latter, subsequently, initiates by autocrine/paracrine actions via its receptor BLT1 the egress of neutrophils from the blood vessel lumen into the interstitial. Compelling evidence suggests that this C5a/C5aR1-LTB₄/BLT1 axis driving granulocyte recruitment in arthritis may represent a more generalizable biological principle critically regulating effector cell recruitment in other IgG autoantibody-induced diseases, such as in pemphigoid diseases. Thus, dual inhibition of C5a and LTB₄, as implemented in nature by the lipocalin coversin in the soft-tick Ornithodoros moubata, may constitute a most effective therapeutic principle for the treatment of IgG autoantibody-driven diseases.

Effectiveness and Safety of Rituximab in Recalcitrant Pemphigoid Diseases

Introduction

Rituximab (RTX) is a monoclonal antibody targeting CD20, a transmembrane protein expressed on B cells, causing B cell depletion. RTX has shown great efficacy in studies of pemphigus vulgaris, but data of pemphigoid diseases are limited.

Objective

To assess the effectiveness and safety of RTX in pemphigoid diseases.

Methods

The medical records of 28 patients with pemphigoid diseases that were treated with RTX were reviewed retrospectively. Early and late endpoints, defined according to international consensus, were disease control (DC), partial remission (PR), complete remission (CR), and relapses. Safety was measured by reported adverse events.

Results

Patients with bullous pemphigoid (n = 8), mucous membrane pemphigoid (n = 14), epidermolysis bullosa acquisita (n = 5), and linear IgA disease (n = 1) were included. Treatment with 500 mg RTX (n = 6) or 1,000 mg RTX (n = 22) was administered on days 1 and 15. Eight patients received additional 500 mg RTX at months 6 and 12. Overall, DC was achieved in 67.9%, PR in 57.1%, and CR in 21.4% of the cases. During follow-up, 66.7% patients relapsed. Repeated treatment with RTX led to remission (PR or CR) in 85.7% of the retreated cases. No significant difference in response between pemphigoid subtypes was found. IgA-dominant cases (n = 5) achieved less DC (20 vs. 81.3%; p = 0.007), less PR (20 vs. 62.5%; p = 0.149), and less CR (0 vs. 18.8%; p = 0.549) compared to IgG-dominant cases (n = 16). Five severe adverse events and three deaths were reported. One death was possibly related to RTX and one death was disease related.

Conclusion

RTX can be effective in recalcitrant IgG-dominant pemphigoid diseases, however not in those where IgA is dominant.