Associations between bullous pemphigoid and hematological diseases: Literature review on mechanistic connections and possible treatments

Bullous pemphigoid is an autoimmune blistering disorder that primarily occurs in elderly patients. Reports indicate that BP coexists with various hematological diseases, including acquired hemophilia A, hypereosinophilic syndrome, aplastic anemia, autoimmune thrombocytopenia, and hematological malignancies. Early identification of these comorbidities contributes to a better control and reduced mortality. This article details the atypical clinical manifestations of BP when associated with hematological diseases, specific diagnostic strategies, underlying mechanistic connections, and possible treatments. Cross-reactivity between autoantibodies and exposed abnormal epitopes, shared cytokines and immune cells, together with genetic susceptibility are the most common connections between BP and hematological diseases. Patients were most often successfully treated with oral steroids combined with medications specifically targeting the hematological disorders. However, the individual comorbidities require specific considerations.

Rituximab, Omalizumab, and Dupilumab Treatment Outcomes in Bullous Pemphigoid: A Systematic Review

Background

Bullous pemphigoid (BP) is the most common autoimmune subepidermal bullous disease of the skin. First-line treatment of systemic corticosteroids may cause serious adverse events. Rituximab, omalizumab, and dupilumab should be explored as alternative treatment options to improve outcomes.

Objective

To systematically review the rituximab, omalizumab, and dupilumab treatment outcomes in bullous pemphigoid.

Methods

A PubMed, Embase, Web of Science, and Cochrane library search were conducted on March 10, 2022. A total of 75 studies were included using Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

Results

Use of rituximab (n=122), omalizumab (n=53) and dupilumab (n=36) were reported in 211 patients with BP. Rituximab led to complete remission in 70.5% (n=86/122) and partial remission in 23.8% (n=29/122) of patients within 5.7 months, with a recurrence rate of 20.5% (n=25/122). 9.0% (n=11/122) of patients died and infection (6.6%, n=8/122) was the most common adverse event. Omalizumab led to complete remission in 67.9% (n=36/53) and partial remission in 20.8% (n=11/53) of patients within 6.6 months, with a recurrence rate of 5.7% (n=3/53). 1.9% (n=1/53) of patients died and thrombocytopenia (1.9%, n=1/53) was observed as the most common adverse event. Dupilumab led to complete remission in 66.7% (n=24/36) and partial remission in 19.4% (n=7/36) of patients within 4.5 months of treatment without any reported adverse events, with a recurrence rate of 5.6% (n=2/36).

Conclusions

Rituximab, omalizumab, and dupilumab have similar clinical benefits for BP patients. However, rituximab resulted in higher recurrence rates, adverse events, and mortality rates.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022316454.

Rituximab and Omalizumab for the Treatment of Bullous Pemphigoid: A Systematic Review of the Literature

BACKGROUND

Bullous pemphigoid (BP) is the most common autoimmune blistering skin disease worldwide. Systemic corticosteroids are considered the mainstay of therapy; however, they may cause significant adverse effects and treatment failures, so additional therapeutic modalities with better safety profiles are required. Rituximab and omalizumab are novel biologic agents administered in recent years for the treatment of BP, yet data regarding their use in the disease are limited.

OBJECTIVE

Our objective was to systematically review the current literature regarding the use of rituximab and omalizumab for the treatment of BP to evaluate their safety and efficacy.

METHODS

A systematic review of all publications evaluating patients with BP treated with rituximab or omalizumab was performed. The primary outcome was clinical response; secondary outcomes were adverse events and recurrence rate.

RESULTS

The systematic review included 35 publications (84 patients: 62 receiving rituximab and 22 receiving omalizumab). In total, 61 of 63 patients had not experienced disease control with systemic corticosteroids before receiving the biologic treatment. Complete response rates were 85% and 84% for rituximab and omalizumab, respectively. The recurrence rate was considerably lower with rituximab (29%) than with omalizumab (80%). Mean time to recurrence was 10.2 and 3.4 months, and adverse effects occurred in 24% and 20% of the patients, respectively.

CONCLUSIONS

Available data, although potentially limited because of publication bias, suggest that rituximab and omalizumab have similar safety profiles and provide clinical benefit for patients with BP. The reviewed data indicated that rituximab resulted in lower recurrence rates and a longer time until recurrence than omalizumab.

The emerging role of rituximab in autoimmune blistering diseases

Rituximab is a chimeric monoclonal antibody that selectively binds to the CD20 molecule on B cells, resulting in their lysis. In autoimmune blistering diseases, the auto-antibody-producing B cells are destroyed and auto-antibody levels are reduced or eliminated. In the majority of patients, rituximab produces rapid clinical response and early resolution. In part, this accounts for the increased use of rituximab. Rituximab does not distinguish normal from pathologic B cells. Hence, shortly after its use, B-cell levels are zero and remain so for several months. In most patients, the use of systemic corticosteroids and immunosuppressive agents are continued after rituximab therapy, while their dosages are significantly decreased. In the majority of patients rituximab is used according to the protocol used in treating lymphoma patients or patients with rheumatoid arthritis. Approximately 50% of patients experience a relapse, requiring additional therapy. Serious adverse events and fatal outcomes have been reported, although their incidence is less than that observed with conventional therapy. Nonetheless, the causes, i.e. infections and septicemia, are similar. Several gaps exist in our understanding of how to optimally benefit from the use of this valuable biological agent. Future studies need to be targeted in designing and implanting protocols that maximize the benefit of rituximab and result in producing sustained prolonged remissions with minimal adverse events and a high quality of life.

Revisiting the role of B cells in skin immune surveillance

Whereas our understanding of the skin immune system has increased exponentially in recent years, the role of B cells in cutaneous immunity remains poorly defined. Recent studies have revealed the presence of B cells within lymphocytic infiltrates in chronic inflammatory skin diseases and cutaneous malignancies including melanoma, and have examined their functional significance in these settings. We review these findings and discuss them in the context of the current understanding of the role of B cells in normal skin physiology, as well as in both animal and human models of skin pathology. We integrate these findings into a model of cutaneous immunity wherein crosstalk between B cells and other skin-resident immune cells plays a central role in skin immune homeostasis.

Rituximab and its use in autoimmune bullous disorders

Rituximab is a chimeric, murine-human, monoclonal antibody against the CD20 antigen of B lymphocytes. It has been used off-label to treat and manage autoimmune and dermatologic diseases as an alternative or adjuvant therapy to systemic treatments. Due to cost, potential complications, and lack of data rituximab is used after standard systemic therapies have failed or the patient is absolutely contraindicated for corticosteroids. More research is required.

Treatment of subepidermal immunobullous diseases

The subepidermal immunobullous diseases are a group of autoimmune blistering disorders of the skin and mucous membranes that share the common features of autoantibody deposition and blister formation at the dermal-epidermal junction or basement membrane. This group includes bullous pemphigoid, linear IgA disease, dermatitis herpetiformis, and epidermolysis bullosa acquisita, among others. Although these disorders share some common features, each disease is unique in its clinical presentation, histopathology, and immunofluorescence patterns, which allows for accurate diagnosis and disease-specific treatment strategy. Treatment of these disorders is complex and requires expert knowledge of disease pathogenesis. We review common treatment approaches for each of these disorders.

Innovative uses of rituximab in dermatology

Since its approval in 1997 by the US Food and Drug Administration, rituximab has been approved for use in certain B-cell lymphomas and treatment-resistant rheumatoid arthritis. Over the past 10 years, many published reports have suggested rituximab's efficacy in several inflammatory conditions in dermatology. This article includes a review of the mechanism of action, dosing, side-effect profile, and the current literature for various off-label uses of this CD20+ B-cell antagonist, rituximab.

Rituximab in severe skin diseases: target, disease, and dose

New clinical indications for rituximab seem to appear every day. This review will trace the use of this monoclonal antibody from lymphoid malignancy, to classic autoimmune disease, and specifically severe autoimmune skin diseases. The history leading to different dosing schema with associated pharmacokinetic data will be discussed. A case of livedoid vasculopathy (atrophie blanche) responding to rituximab will illustrate how the response to therapy can help to elucidate previously obscure pathophysiology.