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

Elevated serum level of B-cell activating factor (BAFF) after rituximab therapy in pemphigus vulgaris patients suggests a possible therapeutic efficacy of B-cell depletion therapies combined with anti-BAFF agents

BACKGROUND

Rituximab is widely used for treatment of pemphigus patients. B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) play key roles in B cell survival, maturation, and differentiation. Here, the effect of rituximab on BAFF and APRIL in patients with pemphigus vulgaris (PV) was studied.

METHODS

Fifty PV cases and 56 healthy individuals were recruited. Patients received rituximab for a period of 6 months. The levels of BAFF and APRIL were measured in the serum samples. The frequency of CD19+ B cells was measured by flow cytometry.

RESULTS

The level of BAFF was significantly higher in the patients at the baseline level than controls (P = 0.0005). The level of BAFF was significantly higher at the 3rd month follow-up compared to the baseline (P = 0.033). There was a significant increase in the BAFF level at the 6th month follow-up compared to baseline (P = 0.0134). There was no significant difference in the CD19+ B cells/total lymphocytes ratio in the PV patients between the 3rd and 6th month follow-ups.

CONCLUSIONS

Elevated BAFF in the sera could be associated with PV immunopathogenesis. Inhibition of BAFF after rituximab therapy might interfere with repopulation of B cells and confer a therapeutic approach in PV.

Epidermolysis bullosa acquisita

Epidermolysis bullosa acquisita is a rare autoimmune disease, characterized by the synthesis of anti-collagen VII autoantibodies, the main component of hemidesmosome anchoring fibrils. The antigen-antibody binding elicits a complex inflammatory response, which culminates in the loss of dermo-epidermal adhesion of the skin and/or mucous membranes. Skin fragility with bullae, erosions, and milia in areas of trauma characterizes the mechanobullous form of the disease. In the inflammatory form of epidermolysis bullosa acquisita, urticarial inflammatory plaques with tense bullae, similar to bullous pemphigoid, or mucosal lesions can determine permanent scars and loss of functionality in the ocular, oral, esophageal, and urogenital regions. Due to the similarity of the clinical findings of epidermolysis bullosa acquisita with other diseases of the pemphigoid group and with porphyria cutanea tarda, the diagnosis is currently confirmed mainly based on the clinical correlation with histopathological findings (pauci-inflammatory subepidermal cleavage or with a neutrophilic infiltrate) and the demonstration of the presence of anti-collagen VII IgG in situ by direct immunofluorescence, or circulating anti-collagen VII IgG through indirect immunofluorescence and/or ELISA. There is no specific therapy for epidermolysis bullosa acquisita and the response to treatment is variable, usually with complete remission in children and a worse prognosis in adults with mucosal involvement. Systemic corticosteroids and immunomodulators (colchicine and dapsone) are alternatives for the treatment of mild forms of the disease, while severe forms require the use of corticosteroid therapy associated with immunosuppressants, intravenous immunoglobulin, and rituximab.

Immunotherapy for Pemphigus: Present and Future

Pemphigus is a chronic and severe autoimmune bullous disease caused by autoantibodies targeting adhesion molecules between keratinocytes. It requires 2–3 years on average to manage the disease. To date, although Rituximab combined with short-term systemic glucocorticoids was accepted as first-line therapy, systemic glucocorticoids remain the primary therapeutic option for pemphigus patients, successfully decreasing morbidity and mortality from pemphigus. However, novel therapeutic strategies are desirable due to the low efficacy in some subset of patients and the long-term severe adverse effects of traditional therapies. Recently, immunotherapy has proved to be encouraging for disease control or cure. Based on the current understanding of the immune mechanisms of pemphigus, we review the immune targets and corresponding agents applied in practice or under clinical trials. The goals of the novel treatments are to improve the quality of life of pemphigus patients by improving efficacy and safety, minimizing side effects, achieving fast disease control, or curing the disease.

Factors Associated With Complete Remission After Rituximab Therapy for Pemphigus

Importance

Rituximab has emerged as a front-line therapy for pemphigus, but prognostic factors for achieving complete remission off therapy (CROT) with oral systemic agents remain unknown.

Objectives

To describe rates of CROT and relapse and identify prognostic factors for achieving CROT after rituximab therapy for pemphigus.

Design, Setting, and Participants

A single-center, retrospective, cohort study was conducted at the University of Pennsylvania including 112 patients with pemphigus treated with rituximab with at least 12 months' clinical follow-up after the start of rituximab therapy. Multivariate regression analysis of factors predictive of CROT and Kaplan-Meier analysis of disease relapse were conducted. The study included patients treated with rituximab from March 15, 2005, until December 19, 2016. Data analysis was performed from December 2017 to June 2018.

Main Outcomes and Measures

The primary study outcome was CROT after 1 cycle. Secondary study outcomes included rate of CROT or the composite end point of CROT or complete remission on minimal therapy after 1 or more cycle, and median time to relapse. Multivariate regression analysis for prognostic variables for CROT, including age, sex, pemphigus subtype, body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared), disease duration, and dosing regimen, was performed.

Results

A total of 112 patients with pemphigus with median 37.8 months (range, 12.1-130.7) follow-up after rituximab therapy were identified. Of these, 65 were women (58.0%). At the time of first rituximab infusion, median age was 52.3 years (range, 20.0-89.3). Including patients who received multiple cycles of rituximab, 79 patients (70.5%) achieved CROT after a median time of 10.5 months (range, 2.0-49.8), and 36 of 72 patients (50.0%) subsequently experienced relapse after a median of 23.3 months (interquartile range, 10.8-50.4 months). Considering only the first cycle of rituximab, 54 patients (48.2%) achieved CROT. Controlling for age, sex, pemphigus subtype, BMI, and disease duration, patients who received lymphoma vs rheumatoid arthritis dosing were 2.70-fold more likely to achieve CROT (odds ratio [OR], 2.70; 95% CI, 1.03-7.12; P = .04). Increasing age was associated with significant increases in achieving CROT (Wald test for trend, P = .01), whereas BMI greater than or equal to 35 was associated with a 0.14 OR (95% CI, 0.03-0.63; P = .01) for achieving CROT, regardless of the dosing regimen. In multivariate analysis, there was no significant difference in CROT rates with sex (OR, 1.01; 95% CI, 0.42-2.50; P = .97), pemphigus subtype (OR, 0.37; 95% CI, 0.09-1.51; P = .17), or disease duration (OR, 0.99; 95% CI, 0.98-1.00; P = .09).

Conclusions and Relevance

Lymphoma dosing and older age may be associated with CROT and BMI greater than or equal to 35 may be a negative prognostic factor for CROT after rituximab therapy for pemphigus. These findings help inform clinical expectations and merit evaluation in future prospective clinical trials.

Rituximab Therapy for Treatment of Pemphigus in Southeast Asians

Background

Rituximab provides more effective and less adverse effects than the standard dose of corticosteroids, but evidence on its efficacy and safety in the Thai population is lacking.

Objective

To evaluate the efficacy and safety of rituximab in the treatment of pemphigus and also to determine prognostic factors linked to the treatment outcomes.

Methods

Pemphigus patients who received rituximab from November 2017 to December 2020 were retrospectively reviewed. The outcome was evaluated by using early (end of consolidation phase [ECP]) and late endpoints (complete remission [CR] on/off therapy, immunological remission [IR], and relapse). Adverse events were noted. Prognostic factors associated with remission and relapse were analyzed.

Results

Of 53 pemphigus patients, all attained ECP within 1.61 months. Almost 80% achieved CR on therapy within a median time of 6.36 months, while 33.9% reached CR off therapy in 19.74 months. Nearly half had IR within a median time of 6.88 months. Relapse occurred in 33.3% with a median time of 14 months. In multivariate analysis, receiving rituximab within 12 months of disease duration was more likely to achieve CR off therapy and IR (hazard ratio [HR] 3.79; 95% confidence interval [CI] 1.38, 10.42; P = 0.01 and HR 2.74; 95% CI 1.12, 6.69; P = 0.027, respectively), whereas older patients and positive anti-desmoglein 1 levels at the time of CR were predictive indicators for relapse (HR 1.07; 95% CI 1.01, 1.13; P = 0.036 and HR 4.38; 95% CI 1.24, 15.46; P = 0.022, respectively). The treatment-related adverse effects occurred in 33.9%.

Conclusion

Rituximab is effective and safe in Thai pemphigus patients. Early administration of rituximab was a predictor of clinical and immunological remission. Older age and persistently positive anti-Dsg1 were correlated with disease relapse.

Rituximab as an adjuvant therapy for pemphigus: experience in 61 patients from a single center with long-term follow-up

BACKGROUND

Rituximab is increasingly being used as an adjuvant treatment for recalcitrant or relapsed pemphigus, but information on its use as a first-line agent is limited. We describe the long-term effectiveness and safety of rituximab in the treatment of pemphigus and compare the treatment outcomes when rituximab is used as first-line treatment vis-à-vis after treatment failure or relapse.

METHODS

This was a retrospective review of 61 patients with pemphigus treated with rituximab at our center from March 2012 to October 2018.

RESULTS

Of the 61 patients, 51 achieved complete remission (on or off treatment) and 10 had partial remission. Forty-nine (80.33%) patients achieved complete remission off prednisolone over a mean period of 8.08 ± 4.45 (range 3-20) months. Seventeen (27.9%) patients relapsed after a mean period of 23.94 ± 13.15 months after first rituximab cycle and 15.97 + 13.7 months after stopping prednisolone. Treatment-related serious adverse effects were noted in six (9.8%) patients. Eighteen (29.5%) patients were administered rituximab as the first-line adjuvant, while 43 (70.5%) patients received it after treatment failure or relapse. In both groups, remission rates on prednisolone (88.9%, 81.4%) and off prednisolone (88.9%, 76.7%) were comparable (P > 0.05). Relapse rates in the group which received rituximab as first-line treatment were about half of those who received rituximab after relapse or treatment failure (16.7% vs. 32.6%, P = 0.348). No statistically significant difference was seen in the times to different treatment endpoints (disease control, complete remission on and off prednisolone, and relapse) between the two groups.

CONCLUSIONS

Rituximab is a safe and effective adjuvant in the treatment of pemphigus. Treatment outcomes were better for patients who received rituximab as first-line treatment, but the difference was not statistically significant.

Updates on diagnosis and management of autoimmune blistering diseases

Over the last several decades, advances in the understanding of the pathogenesis of autoimmune blistering diseases has resulted in significant improvements in diagnosis and management. These improvements include new diagnostic assays and therapies targeted at specific disease mediators. Furthermore, the abundance of new therapies in clinic trials for autoimmune blistering diseases will translate to an enhanced therapeutic armamentarium for clinicians. The aim of this article is to review new developments in the understanding of autoimmune blistering diseases and to summarize advancements in their diagnosis and management.

Mucocutaneous Diseases

Mucocutaneous diseases affecting the oral cavity are predominantly immune mediated or inflammatory. Three of the most common and clinically significant conditions are reviewed in this article: lichen planus, pemphigus vulgaris, and mucous membrane pemphigoid. Because oral manifestations may be the first or only manifestation of mucocutaneous diseases, oral health professionals play a critical role in the early diagnosis and multidisciplinary management of these conditions.

[Therapy of pemphigus]

BACKGROUND

Pemphigus diseases are a heterogeneous group of potentially life-threatening autoimmune bullous disorders. Therefore, rapidly acting and effective therapeutic approaches are essential.

OBJECTIVES

In this review, current therapeutic options in line with available guidelines are presented and new therapeutic approaches are discussed.

METHODS

A literature search was performed using PubMed.

RESULTS

Treatment of pemphigus is based on systemic glucocorticosteroids, frequently combined with potentially corticosteroid-sparing immunosuppressants such as azathioprine and mycophenolate mofetil/mycophenolic acid. Recently, the impressive efficacy of the anti-CD20 antibody rituximab has been shown in a prospective randomized trial. In severe or treatment-refractory cases, immunoadsorption or high-dose intravenous immunoglobulins (IVIG) are recommended. Adjuvant immunoadsorption also seems to be useful within the first 8-12 weeks of therapy in patients with very high autoantibody levels. A variety of new therapeutic approaches is currently evaluated in phase IIa studies.

CONCLUSION

Therapy of pemphigus has been greatly improved by the employment of rituximab. The use of glucocorticosteroids, associated with a high number of adverse events and elevated mortality, could be reduced by the additional use of rituximab. After approval of rituximab for the treatment of pemphigus by the US Food and Drug Administration in 2018, licensing in Europe is expected in 2019.

Robust memory responses against influenza vaccination in pemphigus patients previously treated with rituximab

Rituximab is a therapeutic anti-CD20 monoclonal antibody widely used to treat B cell lymphoma and autoimmune diseases, such as rheumatic arthritis, systemic lupus erythematosus, and autoimmune blistering skin diseases (AIBD). While rituximab fully depletes peripheral blood B cells, it remains unclear whether some preexisting B cell memory to pathogens or vaccines may survive depletion, especially in lymphoid tissues, and if these memory B cells can undergo homeostatic expansion during recovery from depletion. The limited data available on vaccine efficacy in this setting have been derived from rituximab-treated patients receiving concomitant chemotherapy or other potent immunosuppressants. Here, we present an in-depth analysis of seasonal influenza vaccine responses in AIBD patients previously treated with rituximab, who generally did not receive additional therapeutic interventions. We found that, despite a lack of influenza-specific memory B cells in the blood, patients mount robust recall responses to vaccination, comparable to healthy controls, both at a cellular and a serological level. Repertoire analyses of plasmablast responses suggest that they likely derive from a diverse pool of tissue-resident memory cells, refractory to depletion. Overall, these data have important implications for establishing an effective vaccine schedule for AIBD patients and the clinical care of rituximab-treated patients in general and contribute to our basic understanding of maintenance of normal and pathogenic human B cell memory.

Pemphigus

Pemphigus is a group of IgG-mediated autoimmune diseases of stratified squamous epithelia, such as the skin and oral mucosa, in which acantholysis (the loss of cell adhesion) causes blisters and erosions. Pemphigus has three major subtypes: pemphigus vulgaris, pemphigus foliaceus and paraneoplastic pemphigus. IgG autoantibodies are characteristically raised against desmoglein 1 and desmoglein 3, which are cell-cell adhesion molecules found in desmosomes. The sites of blister formation can be physiologically explained by the anti-desmoglein autoantibody profile and tissue-specific expression pattern of desmoglein isoforms. The pathophysiological roles of T cells and B cells have been characterized in mouse models of pemphigus and patients, revealing insights into the mechanisms of autoimmunity. Diagnosis is based on clinical manifestations and confirmed with histological and immunochemical testing. The current first-line treatment is systemic corticosteroids and adjuvant therapies, including immunosuppressive agents, intravenous immunoglobulin and plasmapheresis. Rituximab, a monoclonal antibody against CD20⁺ B cells, is a promising therapeutic option that may soon become first-line therapy. Pemphigus is one of the best-characterized human autoimmune diseases and provides an ideal paradigm for both basic and clinical research, especially towards the development of antigen-specific immune suppression treatments for autoimmune diseases.

Setting the target for pemphigus vulgaris therapy

Despite the rising incidence of autoimmunity, therapeutic options for patients with autoimmune disease still rely on decades-old immunosuppressive strategies that risk severe and potentially fatal complications. Thus, novel therapeutic approaches for autoimmune diseases are greatly needed in order to minimize treatment-related toxicity. Such strategies would ideally target only the autoreactive immune components to preserve beneficial immunity. Here, we review how several decades of basic, translational, and clinical research on the immunology of pemphigus vulgaris (PV), an autoantibody-mediated skin disease, have enabled the development of targeted immunotherapeutic strategies. We discuss research to elucidate the pathophysiology of PV and how the knowledge afforded by these studies has led to the preclinical and clinical testing of targeted approaches to neutralize autoantibodies, to induce antigen-specific tolerance, and to specifically eliminate autoreactive B cells in PV.

Biologics in dermatology: adverse effects

Biologics are a group of drugs that precisely affect certain specific steps in the immune response and are an extremely useful group when used in an appropriate setting. However, their use can often be a double-edged sword. Careful patient selection and thorough knowledge of adverse effects is a key to their successful use in various disorders. The initial enthusiasm has gradually given way to a more cautious approach wherein a balance is sought between clinical usefulness and expected side effects. The adverse effects of the biologics most commonly used in dermatology have been carefully listed for ready reference. The plausible causes of the adverse reactions are succinctly outlined along with their incriminating factor(s). Besides, in brief, the attention has been focused on their management. The content should provide an essential didactic content for educating the practitioner.

CD19 mRNA quantification improves rituximab treatment-to-target approach: a proof of concept study

We compared pre-amplification (PA) RT-PCR blood CD19 mRNA quantification with flow cytometry (FC), to personalize rituximab re-treatment in neuromyelitis optica spectrum disorders (NMOSDs) patients. 47 blood samples from 3 NMOSDs patients were studied. PA-RT-PCR quantified CD19 in all samples, and a positivity threshold was defined, whereas CD19+ B cells were under threshold in 31/47 samples by FC. In all samples where CD19+ B cells were above FC threshold, they resulted above the PA-RT-PCR threshold. CD19 mRNA was above threshold in 8 other samples, resulted negative by FC, and preceded the FC positivity in 7/8 samples by 1-3 months, showing major sensitivity.

Pemphigus

Pemphigus vulgaris and paraneoplastic pemphigus are 2 subtypes of pemphigus that involve the oral mucosa. These autoimmune blistering disorders have antibodies targeted against proteins of keratinocyte adhesion, thereby causing acantholysis. Clinical findings include oral erosions and flaccid cutaneous bullae and erosions. Further malignancy workup in patients with suspected paraneoplastic pemphigus is warranted. Retrospective uncontrolled studies suggest that immunosuppressive agents reduce mortality in pemphigus vulgaris and cohort uncontrolled studies of rituximab, a monoclonal antibody against CD20, suggest it is an effective treatment for refractory patients. Ongoing studies will define its role in early disease.

p38 MAPK Signaling in Pemphigus: Implications for Skin Autoimmunity

p38 mitogen activated protein kinase (p38 MAPK) signaling plays a major role in the modulation of immune-mediated inflammatory responses and therefore has been linked with several autoimmune diseases. The extent of the involvement of p38 MAPK in the pathogenesis of autoimmune blistering diseases has started to emerge, but whether it pays a critical role is a matter of debate. The activity of p38 MAPK has been studied in great detail during the loss of keratinocyte cell-cell adhesions and the development of pemphigus vulgaris (PV) and pemphigus foliaceus (PF). These diseases are characterised by autoantibodies targeting desmogleins (Dsg). Whether autoantibody-antigen interactions can trigger signaling pathways (such as p38 MAPK) that are tightly linked to the secretion of inflammatory mediators which may perpetuate inflammation and tissue damage in pemphigus remains unclear. Yet, the ability of p38 MAPK inhibitors to block activation of the proapoptotic proteinase caspase-3 suggests that the induction of apoptosis may be a consequence of p38 MAPK activation during acantholysis in PV. This review discusses the current evidence for the role of p38 MAPK in the pathogenesis of pemphigus. We will also present data relating to the targeting of these cascades as a means of therapeutic intervention.

Adjuvant rituximab therapy of pemphigus: a single-center experience with 31 patients

BACKGROUND

We conducted a retrospective study of patients with pemphigus vulgaris (n = 24) and foliaceus (n = 7) treated with adjuvant rituximab to determine efficacy and adverse events. The end point for efficacy was complete remission of disease taking no or minimal therapy.

OBSERVATIONS

Eighteen patients (58%) achieved the study end point. Of these, 13 patients achieved complete remission off systemic therapy. Patients achieving the study end point had a median disease duration before rituximab therapy of 19 months vs 86 months in those not achieving the end point (P = .01). For the 18 patients achieving the end point, the median (SD) duration of remission was 19 (2) months. Eight of these 18 patients (44%) relapsed from 6 to 17 months after treatment. Serious adverse events attributed to rituximab treatment (osteomyelitis or phlegmon) occurred in 2 patients (6%). In paired serum samples from 10 patients before and after rituximab treatment, the percent change in serum desmoglein index value (median, -80%) was unrelated to the percent change in pneumococcal antibodies (median, +8%) (Spearman rank correlation coefficient r = -0.2).

CONCLUSIONS

Patients treated with rituximab earlier in the course of disease may have better outcomes. A discussion of rituximab's mechanism of action supports the rationale for early therapy. Prospective clinical studies are necessary to substantiate this observation.

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.