Treatment of refractory pemphigus vulgaris with anti‐CD20 monoclonal antibody (rituximab): Five cases

Long-term experience with rituximab therapy for treatment-resistant moderate-to-severe pemphigus

BACKGROUND

Rituximab appears to be effective for treating pemphigus, although there are limited long-term data.

METHODS

This retrospective single-center study evaluated patients with conventional treatment-resistant pemphigus who received rituximab during September 2010-December 2019. The first rituximab cycle was based on the rheumatoid arthritis protocol in all patients except one patient, and additional single doses (500 mg or 1000 mg) were administered after clinical and/or serological relapse. The consensus definitions were used for complete remission off therapy, complete remission on minimal therapy, and clinical relapse. Serological relapse was defined as a progressive ≥2-fold increase in anti-desmoglein titers (vs. previous the measurement).

RESULTS

The study included 52 patients with pemphigus vulgaris and 1 patient with pemphigus foliaceus. The mean number of infusions was 5 and the average follow-up after the first infusion was 56 months. The average time to clinical and/or serological relapse was 12 months. Complete remission was achieved in 84.9% of patients, including after the first rituximab cycle in 25 patients (47.1%). Two patients died during the follow-up period.

CONCLUSION

Additional rituximab cycles may help achieve and prolong remission in patients with moderate-to-severe pemphigus resistant to conventional therapies. However, prospective trials are needed to identify the optimal dosing protocol.

Rituximab in pemphigus

Pemphigus is a severe autoimmune blistering disease mediated by pathogenic anti-desmoglein antibodies leading to an inter keratinocyte disjunction. Rituximab is a monoclonal antibody that binds to the CD-20 antigen of B lymphocytes, which causes B-cell depletion and a subsequent reduction in pathogenic autoantibodies. Its therapeutic role in pemphigus has been progressively growing with increasing evidence of successful outcomes. Rituximab was initially off-labeled used as an alternative in patients with recalcitrant or relapsing pemphigus and in patients with contraindications to systemic corticosteroids. Recently, a large randomized clinical trial has shown that first-line use of rituximab combined with short-term prednisone regimen was both more effective and potentially safer than a standard regimen of high doses of corticosteroids in patients with moderate to severe pemphigus.

Management of Pemphigus Vulgaris

INTRODUCTION

Pemphigus vulgaris (PV) is a chronic, autoimmune, vesiculobullous disease. As a result of the relative rarity of PV, published randomized controlled trials (RCTs) are limited, which makes it difficult to evaluate the efficacy of different treatment regimens in this disease. This also precludes conduct of a meta-analysis.

METHODS

English-language publications describing treatment outcomes of patients with PV were identified by searches of electronic databases through May 2015, and additionally by review of the bibliography of these publications. A total of 89 papers, which included 21 case reports, 47 case series, 8 RCTs, and 13 observational studies, were identified. The findings from these publications, including information on disease course and prognosis, medications used, treatment responses, and side effects, are summarized in the tables and text of this review.

RESULTS

Prior to availability of corticosteroid therapy, PV had a high fatality rate. Early publications from the 1970s reported high-dose, prolonged corticosteroid use and significant associated side effects. Later reports described use of corticosteroids along with steroid-sparing adjuvants, which allows a reduction in the total dose of corticosteroids and a reduction in observed mortality and morbidity. For the majority of patients in these reports, a long-term course on medications lasting about 5-10 years was observed; however, subgroups of patients requiring shorter courses or needing longer-term therapy have also been described. Early diagnosis of PV and early initiation of treatment were prognostic factors. In recent publications, commonly used initial regimens include corticosteroids in combination with mycophenolate or azathioprine; whereas, for patients with inadequate response to these regimens, adjuvants such as intravenous immunoglobulin (IVIg) or rituximab are used.

CONCLUSION

The review findings emphasize the importance of early diagnosis, early initiation of treatment, and use of steroid-sparing adjuvants to allow a reduced total dose and duration on corticosteroids. Also highlighted is the need for more RCTs.

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.

Rituximab in the treatment of pemphigus vulgaris

INTRODUCTION

Rituximab is increasingly used in patients with pemphigus vulgaris (PV) who are nonresponders to conventional therapy.

METHODS

A PubMed search was conducted using the words pemphigus vulgaris and rituximab therapy from papers published between 2000 and 2012. Two protocols were used. In the lymphoma protocol, patients received four weekly infusions of rituximab (dose 375 mg/m(2)). The rheumatoid arthritis (RA) protocol consisted of two infusions of 1,000 mg each 15 days apart. The variables recorded from each study included clinical remission off or on therapy, relapse rate, incidence of serious adverse events, concomitant therapies, duration of follow-up, and when available, levels of B cells and autoantibodies.

RESULTS

Forty-two studies were found, which reported 272 patients; 180 were treated by the lymphoma protocol and 92 by the RA protocol. Both protocols were effective in treating recalcitrant PV. The lymphoma protocol had a lower response rate, relapse rate and serious infections, but higher mortality, and there were nonresponders. The RA protocol produced a higher response rate, relapse rate, number of infections, but lower mortality rate, and lacked nonresponders. The cumulative follow-up for patients treated with the lymphoma protocol was 15.44 months (range 1-41) and 21.04 months (range 8.35-29) for the RA protocol. A major concern in both protocols was the high infection rates, some of which were fatal. A different protocol using a combination of rituximab with intravenous immunoglobulin in a defined manner with a definitive endpoint, used in a limited cohort of patients, showed promising results.

CONCLUSION

Neither protocol produced a sustained clinical remission and both required continued systemic therapy. Before initiation of treatment, physicians should have a specific goal and endpoint and be aware of its potential side effects and lack of information on its long-term effects. Patients should be carefully monitored during and after therapy.

Urban legends: pemphigus vulgaris

Pemphigus vulgaris (PV) is the most common type of pemphigus. PV pathogenesis is still debated, and treatment remains challenging. We investigated five controversial topics: (1) What are the target antigens in PV? (2) Do desmogleins adequately address PV pathophysiology? (3) How does acantholysis occur in PV? (4) Is PV still a lethal disease? (5) What is the role of rituximab (RTX) in PV treatment? Results from extensive literature searches suggested the following: (1) Target antigens of PV include a variety of molecules and receptors that are not physically compartmentalized within the epidermis. (2) PV is caused by a variety of autoantibodies to keratinocyte self-antigens, which concur to cause blistering by acting synergistically. (3) The concept of apoptolysis distinguishes the unique mechanism of autoantibody-induced keratinocyte damage in PV from other known forms of cell death. (4) PV remains potentially life-threatening largely because of treatment side effects, but it is uncertain which therapies carry the highest likelihood of lethal risk. (5) RTX is a very promising treatment option in patients with widespread recalcitrant or life-threatening PV. RTX's cost is an issue, its long-term side effects are still unknown, and randomized controlled trials are needed to establish the optimal dosing regimen.

Relevance of rituximab therapy in pemphigus vulgaris: analysis of current data and the immunologic basis for its observed responses

Treatment of pemphigus vulgaris (PV) patients with rituximab therapy has not been critically evaluated. This article will provide in significant detail the available data to date, in order to provide a clinical and immunologic basis for clinicians to decide how best to treat recalcitrant PV patients with rituximab. PV is an autoimmune blistering disorder that affects the skin and mucous membranes. The immunopathology is well characterized, including the target antigens. PV patients have traditionally been treated with systemic corticosteroids and adjuvant immunosuppressive therapies. Clinical remission has been achieved in roughly 30% of patients. However, many patients experience severe side effects from this immunosuppression, including death. B-cell depletion therapy with rituximab therapy has been used to treat several autoimmune diseases including PV. In this article, we examined the data on 153 patients with PV who have been treated with rituximab. Our focus is on the clinical response of the patients with emphasis on adjuvant therapies, dosing regimens, potential adverse events and mechanism of action related to B-cell modulation during therapy. Importantly, the use of rituximab has increased clinical remission rates to 65% including many patients who were able to discontinue all systemic medications. Finally, an expert commentary is provided, which includes suggestions for optimizing current therapy and recommends the future direction of the field. The authors strongly endorse the use of rituximab in treatment of PV patients, particularly those nonresponsive to or who develop serious side effects to conventional therapy. Proper monitoring of patients including peripheral B-cell counts and overt signs of infection are warranted, given the potential for prolonged B-cell depletion.

Current status on B-cell depletion therapy in autoimmune diseases other than rheumatoid arthritis

Since the approval of the chimeric anti-CD20 antibody rituximab for the treatment of adults with severe-to-moderate rheumatoid arthritis after an inadequate response to TNF blockade, B-cell depletion therapy has been used for the treatment of a broad range of refractory autoimmune disorders. Based on current experiences and a literature search, a systematic review and evaluation of the current status of B-cell depletion therapy in autoimmune diseases other than rheumatoid arthritis, including rheumatic, nephrologic, dermatologic and neurologic autoimmune entities, was performed by an international group of experts based at several academic centres. Although important questions remain about the value and place of B-cell depletion in autoimmune diseases other than RA, preliminary data indicate the value of this therapeutic approach in otherwise refractory patients. However, given the lack of robust data from large randomised controlled trials, anti-CD20 therapy should be considered on an individual basis in otherwise refractory patients and its use based on a risk/benefit net calculation.