Rituximab Maintenance Therapy Reduces Rate of Relapse of Pancreaticobiliary Immunoglobulin G4-related Disease

Efficacy of Rituximab in Autoimmune-Mediated IgG4 Pancreaticobiliary Disease: A Systematic Review and Meta-Analysis

BACKGROUND AND AIMS

IgG4 pancreaticobilliary disease (IgG4-PBD) typically shows a rapid improvement with glucocorticoid treatment, yet most patients experience a recurrence. Rituximab (RTX) has emerged as a hopeful approach to prevent relapses in IgG4-PBD. Nevertheless, there is a lack of data on the efficacy and safety of RTX in IgG4-PBD. In this study, we aim to perform a systematic review and meta-analysis to study the pooled efficacy of RTX in this patient population.

METHODS

Multiple databases, including MEDLINE, SCOPUS, and Embase, were searched (in March 2024) using specific terms for studies evaluating the efficacy and safety of RTX in IgG4 pancreatic biliary disease. Outcomes of interest were relapse, remission, partial remission rates, and adverse events. Standard meta-analysis methods were used using the random-effects model. I2% heterogeneity was used to assess the heterogeneity.

RESULTS

Twelve studies were included in the study (257 patients). The pooled rate of complete remission was 68% (54% to 80%), I2 =53%, respectively. The pooled relapse rate was 23% (13% to 36%), I2=64%. The pooled rate of total adverse events was 21% (12% to 35%), I2=52%. The pooled partial remission rate is 16% (7% to 32%), I2=25%. The pooled rate of complete and partial remission was 81% (66% to 90%), I2=75%. The pooled infusion reaction and infection were 12% (7% to 18%), I2=0% and 14% (8% to 22%), I2=16%, respectively.

CONCLUSION

RTX therapy appears effective in inducing and maintaining remission of pancreaticobiliary disease with a low rate of side effects. RTX presents as a promising treatment option for patients grappling with recurrent or unresponsive IgG4-related ailments. In addition, RTX emerges as an attractive alternative for individuals intolerant to steroids or experiencing IgG4-related disease relapses. Future studies comparing RTX with other immunomodulators will offer deeper insights into relapse factors and elucidate the appropriateness of utilizing this maintenance treatment following the initial flare.

Efficacy and safety of rituximab induction therapy and effect of rituximab maintenance for IgG4-related disease: a systematic review and meta-analysis

BACKGROUND

Previous studies have reported that rituximab (RTX) therapy might be beneficial in reducing relapse rates in patients with IgG4-related disease (IgG4-RD). Therefore, we aimed to systematically assess the efficacy and safety of RTX induction treatment and the effect of RTX maintenance in patients with IgG4-RD.

METHODS

The protocol was registered in the PROSPERO (CRD42023427352). PubMed, Embase, the Cochrane database, Scopus, and the Web of Science were interrogated to identify studies that evaluated the impact of RTX on prognosis in IgG4-RD. We explored the impact of various subgroups of factors on relapse outcomes and focused on the possible role of maintenance therapy in reducing relapse rates. The pooled incidence of adverse events of RTX therapy and the influencing factors have also been evaluated.

RESULTS

Eighteen studies comprising 374 patients (mean age 56.0 ± 8.7 years; male 73.7 %) with a mean follow-up duration of 23.4 ± 16.3 months were included. The pooled estimate of the response rate, complete remission rate, overall relapse rate, adverse event rate, and serious adverse event rate of RTX induction therapy were 97.3 % (95 % CI, 94.7 %-99.1 %), 55.8 % (95 % CI, 39.6 %-71.3 %), 16.9 % (95 % CI, 8.7 %-27.1 %), 31.6 % (95 % CI, 16.7 %-48.9 %) and 3.9 % (95 % CI, 0.8 %-8.9 %), respectively. In subgroup analysis, the pooled relapse rate was significantly lower in studies with maintenance than without maintenance (2.8% vs 21.5 %, p < 0.01). Pooled Kaplan-Meier relapse curves also demonstrated that RTX maintenance therapy provided a better prognosis.

CONCLUSIONS

RTX induction therapy appears to have satisfactory efficacy in the induction of remission in IgG4-RD. In addition, prophylactic RTX maintenance therapy after induction may be beneficial in preventing relapse of IgG4-RD.

Case report: Isolated immunoglobulin G4-related sclerosing cholangitis misdiagnosed as hilar cholangiocarcinoma

Background

Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is frequently accompanied with type 1 autoimmune pancreatitis (AIP). Isolated IgG4-SC which is not accompanied with AIP is uncommon in clinical practice, and its manifestations are similar to those of hilar cholangiocarcinoma.

Case presentation

A 55-year-old male presented with persistent aggravation of icteric sclera and skin. He was initially diagnosed with hilar cholangiocarcinoma and underwent surgery. However, positive IgG4 plasma cells were found in the surgical specimens. Thus, a pathological diagnosis of IgG4-SC was established. After that, steroid therapy was given and initially effective. But he was steroid dependent, and then received rituximab therapy twice. Unfortunately, the response to rituximab therapy was poor.

Conclusion

It is crucial to differentiate isolated IgG4-SC from hilar cholangiocarcinoma to avoid unnecessary surgery. Future studies should further explore effective treatment strategy in patients who do not respond to steroids therapy. It is also required to develop novel and accurate diagnostic approaches to avoid unnecessary surgical procedures.

Current and future advances in practice: IgG4-related disease

IgG4-related disease (IgG4-RD) is an increasingly recognized cause of fibroinflammatory lesions in patients of diverse racial and ethnic backgrounds and is associated with an increased risk of death. The aetiology of IgG4-RD is incompletely understood, but evidence to date suggests that B and T cells are important players in pathogenesis, both of which are key targets of ongoing drug development programmes. The diagnosis of IgG4-RD requires clinicopathological correlation because there is no highly specific or sensitive test. Glucocorticoids are highly effective, but their use is limited by toxicity, highlighting the need for studies investigating the efficacy of glucocorticoid-sparing agents. B cell-targeted therapies, particularly rituximab, have demonstrated benefit, but no randomized clinical trials have evaluated their efficacy. If untreated or under-treated, IgG4-RD can cause irreversible organ damage, hence close monitoring and consideration for long-term immunosuppression is warranted in certain cases.

Immune dysregulation in immunoglobulin G4-related disease

(IgG4-RD) is an immune-mediated fibrotic disorder characterized by severe resolution of inflammation and dysregulation of wound healing. IgG4-RD has been considered a unique disease since 2003, and significant progress has been achieved in the understanding of its essential features. The central role of B cells in IgG4-RD has been demonstrated by the robust clinical responsiveness of IgG4-RD to B cell depletion and the identification of multiple self-antigens that promote B cell expansion. Studies have increasingly revealed critical roles of these B cells and T cells in the pathogenesis of IgG4-RD, and we and other authors further identified CD4⁺ cytotoxic T lymphocytes as the main tissue-infiltrating CD4⁺ T cell subset in IgG4-RD tissues. Additionally, T follicular helper cell subsets that play a role in IgG4 isotype switching have been identified. In this review, we discuss research on IgG4-RD and the roles of B cell and T cell subsets, as well as the functions of CD4⁺ cytotoxic T cells in IgG4-RD pathogenesis. We highlight our findings from ongoing research using single-cell analysis of infiltrating CD4⁺ cytotoxic T cells, CD4⁺ follicular helper T cells, and infiltrating B cells in IgG4-RD and propose a model for the pathogenesis of IgG4-RD.

IgG4-related cholangitis - a mimicker of fibrosing and malignant cholangiopathies

IgG4-related cholangitis (IRC) is the major hepatobiliary manifestation of IgG4-related disease (IgG4-RD), a systemic fibroinflammatory disorder. The pathogenesis of IgG4-RD and IRC is currently viewed as multifactorial, as there is evidence of a genetic predisposition while environmental factors, such as blue-collar work, are major risk factors. Various autoantigens have been described in IgG4-RD, including annexin A11 and laminin 511-E8, proteins which may exert a partially protective function in cholangiocytes by enhancing secretion and barrier function, respectively. For the other recently described autoantigens, galectin-3 and prohibitin 1, a distinct role in cholangiocytes appears less apparent. In relation to these autoantigens, oligoclonal expansions of IgG4+ plasmablasts are present in patients with IRC and disappear upon successful treatment. More recently, specific T-cell subtypes including regulatory T cells, follicular T helper 2 cells, peripheral T helper cells and cytotoxic CD8+ and CD4+ SLAMF7+ T cells have been implicated in the pathogenesis of IgG4-RD. The clinical presentation of IRC often mimics other biliary diseases such as primary sclerosing cholangitis or cholangiocarcinoma, which may lead to inappropriate medical and potentially invalidating surgical interventions. As specific biomarkers are lacking, diagnosis is made according to the HISORt criteria comprising histopathology, imaging, serology, other organ manifestations and response to therapy. Treatment of IRC aims to prevent or alleviate organ damage and to improve symptoms and consists of (i) remission induction, (ii) remission maintenance and (iii) long-term management. Glucocorticosteroids are highly effective for remission induction, after which immunomodulators can be introduced for maintenance of remission as glucocorticosteroid-sparing alternatives. Increased insight into the pathogenesis of IRC will lead to improved diagnosis and novel therapeutic strategies in the future.

Clinical characteristics and outcome of autoimmune pancreatitis based on serum immunoglobulin G4 level: A single-center, retrospective cohort study

BACKGROUND

Autoimmune pancreatitis (AIP) has been linked with elevated immunoglobulin (Ig) G4 levels. The characteristics and outcomes of AIP based on serum markers have not been fully evaluated.

AIM

To compare clinical features, treatment efficacy, and outcome of AIP based on serum IgG4 levels and analyze predictors of relapse.

METHODS

A total of 213 patients with AIP were consecutively reviewed in our hospital from 2006 to 2021. According to the serum IgG4 level, all patients were divided into two groups, the abnormal group (n = 148) with a high level of IgG4 [> 2 × upper limit of normal (ULN)] and the normal group (n = 65). The t-test or Mann-Whitney U test was used to compare continuous variables. Categorical parameters were compared by the χ2 test or Fisher's exact test. Kaplan-Meier curves and log-rank tests were established to assess the cumulative relapse rates. Univariate and multivariate analyses were used to investigate potential risk factors of AIP relapse.

RESULTS

Compared with the normal group, the abnormal group had a higher average male age (60.3 ± 10.4 vs 56.5 ± 12.9 years, P = 0.047); higher level of serum total protein (72.5 ± 7.9 g/L vs 67.2 ± 7.5 g/L, P < 0.001), IgG4 (1420.5 ± 1110.9 mg/dL vs 252.7 ± 106.6 mg/dL, P < 0.001), and IgE (635.6 ± 958.1 IU/mL vs 231.7 ± 352.5 IU/mL, P = 0.002); and a lower level of serum complement C3 (100.6 ± 36.2 mg/dL vs 119.0 ± 45.7 mg/dL, P = 0.050). In addition, a lower number of cases with abnormal pancreatic duct and pancreatic atrophy (23.6% vs 37.9%, P = 0.045; 1.6% vs 8.6%, P = 0.020, respectively) and a higher rate of relapse (17.6% vs 6.2%, P = 0.030) were seen in the abnormal group. Multivariate analyses revealed that serum IgG4 [(> 2 × ULN), hazard ratio (HR): 3.583; 95% confidence interval (CI): 1.218-10.545; P = 0.020] and IgA (> 1 × ULN; HR: 5.908; 95%CI: 1.199-29.120; P = 0.029) and age > 55 years (HR: 2.383; 95%CI: 1.056-5.378; P = 0.036) were independent risk factors of relapse.

CONCLUSION

AIP patients with high IgG4 levels have clinical features including a more active immune system and higher relapse rate. Several factors, such as IgG4 and IgA, are associated with relapse.

A Case of Immunoglobulin G4-Related Disease Presenting as a Parapharyngeal Mass

Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition characterized by tissue infiltration with lymphocytes and IgG4-secreting plasma cells. The presentation of IgG4-RD is heterogenous, making it difficult to diagnose. IgG4-RD presenting as a parapharyngeal mass is extremely rare. This report discusses the case of a 69-year-old African American female presenting with intermittent bilateral frontal headaches. Initial imaging revealed an ill-defined parapharyngeal mass encasing the left internal carotid artery and left internal jugular vein. Subsequent biopsy and immunohistochemistry showed a high concentration of IgG4-positive plasma cells with storiform fibrosis, despite normal serum IgG4 levels. The patient opted for conservative management. The localized parapharyngeal mass has remained stable over two years on annual imaging. This case report highlights that IgG4-RD can have varied and nonspecific presentations requiring high clinical suspicion to diagnose. Histopathology and IgG4 staining are vital to confirm the diagnosis of IgG4-RD, particularly in atypical cases not meeting the standard inclusion criteria.

B-Cell depletion therapy in IgG4-related disease: State of the art and future perspectives

IgG4-related disease (IgG4-RD) is an increasingly recognized immune-mediated fibroinflammatory disorder that promptly responds to glucocorticoids but commonly relapses during steroid tapering or after discontinuation. In the last few years, B-cell depletion therapy with rituximab (RTX) proved to be effective in the induction of remission and maintenance treatment of IgG4-RD, providing a new powerful tool in the management of this emerging condition. In this review, we outline the pathogenetic rationale for using B-cell depleting agents in IgG4-RD, we summarize available clinical experience with RTX in this disease, and we describe future possible therapies targeting B-lymphocytes that are now in the pipeline.

IgG4-related autoimmune liver disease

The term IgG4-related autoimmune liver disease (AILD) refers to hepato-biliary manifestations of Immunoglobin G4-related disease (IgG4-RD) including IgG4-related sclerosing cholangitis and IgG4-related pseudotumor. The association of some forms of autoimmune hepatitis to IgG4-RD remains controversial. Although autoimmune phenomena have not been clearly observed in IgG4-AILD, perturbation of the adaptive immune system and activation of the humoral response represent established pathophysiological hallmarks and potential therapeutic targets. Clinical manifestations of IgG4-AILD are virtually indistinguishable from bile duct cancer or primary sclerosing cholangitis and are due to mass forming lesions and thickening of the biliary tract that progressively lead to biliary ducts obstruction. There are no current reliable biomarkers for IgG4-AILD and diagnosis should rely on the integration of clinical, serological, radiological, and histological findings. In analogy to most IgG4-RD manifestations, and in contrast to its major mimickers, IgG4-AILD promptly responds to glucocorticoids but frequently relapses, thus requiring long-term maintenance therapy to avoid progressive fibrosclerotic disease and liver cirrhosis. Accumulating evidence on the efficacy of B-cell depletion therapy in patients with systemic IgG4-RD is gradually changing the treatment paradigm of IgG4-AILD and biologics will be increasingly used also for gastroenterological manifestations of IgG4-RD to spare glucocorticoids and traditional immunosuppressive agents. Looking ahead, identification of reliable biomarkers and of mini-invasive strategies to obtain informative biopsies from the biliary tree represent unavoidable priorities to optimize diagnosis and management of IgG4-AILD.

Development of an algorithm for IgG4-related disease management

OBJECTIVES

IgG4-related disease (IgG4-RD) is a rare fibro-inflammatory condition affecting multiple organs lacking standardized management. In this article, we review the evidence available to provide European expert-based statements on the management of IgG4-RD which were integrated in a final algorithm.

METHODS

A panel of nine European experts in IgG4-RD from different specialties was asked to elaborate a set of consensus statements through a Delphi exercise. Three rounds of survey were taken. Consensus was reached when ≥75% of the responders agreed with a statement.

RESULTS

Thirty-one statements on induction treatment, maintenance treatment, non-pharmacological treatment, and general considerations were assessed. Patients should be treated promptly in situations when there is an immediate organ threatened, or when organ damage is anticipated. Glucocorticoids (GC) are considered the first line of treatment and should be progressively tapered. Maintenance treatment is recommended for patients with high disease activity or with risk factors for relapse. Rituximab is effective for induction and maintenance of remission, but its use can be limited by economics. Low dose GC with or without GC-sparing agents can be used for maintenance therapy. Stenting or surgery should be ancillary to pharmacological treatment. Follow up should be based on physical examination, blood works, and imaging studies. Furthermore, it should be tailored on individual patient clinical history. 18-fluorodeoxyglucose positron emission tomography/computerized tomography may provide additional information over other imaging modalities.

CONCLUSIONS

These new statements and algorithm reached a high degree of agreement and may help guiding the clinical management of IgG4-RD.

Recent advances in the management of autoimmune pancreatitis in the era of artificial intelligence

Autoimmune pancreatitis (AIP) is a type of immune-mediated pancreatitis subdivided into two subtypes, type 1 and type 2 AIP. Furthermore, type 1 AIP is considered to be the pancreatic manifestation of the immunoglobulin G4 (IgG4)-related disease. Nowadays, AIP is increasingly researched and recognized, although its diagnosis represents a challenge for several reasons: False positive ultrasound-guided cytological samples for a neoplastic process, difficult to interpret levels of IgG4, the absence of biological markers to diagnose type 2 AIP, and the challenging clinical identification of atypical forms. Furthermore, 60% and 78% of type 1 and type 2 AIP, respectively, are retrospectively diagnosed on surgical specimens of resected pancreas for suspected cancer. As distinguishing AIP from pancreatic ductal adenocarcinoma can be challenging, obtaining a definitive diagnosis can therefore prove difficult, since endoscopic ultrasound fine-needle aspiration or biopsy of the pancreas are suboptimal. This paper focuses on recent innovations in the management of AIP with regard to the use of artificial intelligence, new serum markers, and new therapeutic approaches, while it also outlines the current management recommendations. A better knowledge of AIP can reduce the recourse to surgery and avoid its overuse, although such an approach requires close collaboration between gastroenterologists, surgeons and radiologists. Better knowledge on AIP and IgG4-related disease remains necessary to diagnose and manage patients.

Autoimmune Pancreatitis: From Pathogenesis to Treatment

Autoimmune pancreatitis (AIP) is a rare disease. The diagnosis of AIP is difficult and should be made by a comprehensive evaluation of clinical, radiological, serological, and pathological findings. Two different types of AIP have been identified: autoimmune pancreatitis type 1 (AIP-1), which is considered a pancreatic manifestation of multiorgan disease related to IgG4, and autoimmune pancreatitis type 2 (AIP-2), which is considered a pancreas-specific disease not related to IgG4. Although the pathophysiological conditions seem to differ between type 1 and type 2 pancreatitis, both respond well to steroid medications. In this review, we focused on the pathogenesis of the disease to develop a tool that could facilitate diagnosis and lead to the discovery of new therapeutic strategies to combat autoimmune pancreatitis and its relapses. The standard therapy for AIP is oral administration of corticosteroids. Rituximab (RTX) has also been proposed for induction of remission and maintenance therapy in relapsing AIP-1. In selected patients, immunomodulators such as azathioprine are used to maintain remission. The strength of this review, compared with previous studies, is that it focuses on the clear difference between the two types of autoimmune pancreatitis with a clearly delineated and separate pathogenesis. In addition, the review also considers various therapeutic options, including biologic drugs, such as anti-tumor necrosis factor (TNF) therapy, a well-tolerated and effective second-line therapy for AIP type 2 relapses or steroid dependence. Other biologic therapies are also being explored that could provide a useful therapeutic alternative to corticosteroids and immunosuppressants, which are poorly tolerated due to significant side effects.

Effect of low-dose rituximab treatment on autoimmune nodopathy with anti-contactin 1 antibody

Background

Autoimmune nodopathy with anti-contactin-1 (CNTN1) responds well to rituximab instead of traditional therapies. Although a low-dose rituximab regimen was administered to patients with other autoimmune diseases, such as myasthenia gravis and neuromyelitis optica spectrum disorders, and satisfactory outcomes were obtained, this low-dose rituximab regimen has not been trialed in anti-CNTN1-positive patients.

Methods

Anti–CNTN1 nodopathy patients were enrolled in this prospective, open-label, self-controlled pilot study. A cell-based assay was used to detect anti-CNTN1 antibodies and their subclasses in both serum and cerebrospinal fluid. Clinical features were evaluated at baseline, 2 days, 14 days, and 6 months after single low-dose rituximab treatment (600 mg). The titers of the subclasses of anti-CNTN1 antibody and peripheral B cells were also evaluated at baseline, 2 days, and 6 months after the rituximab regimen.

Results

Two patients with anti–CNTN1 antibodies were enrolled. Both patients had neurological symptoms including muscle weakness, tremor, sensory ataxia, numbness and mild nephrotic symptoms. In the field of neurological symptoms, sensory ataxia markedly improved, and the titer of anti-CNTN1 antibody as well as CD19+ B cells decreased only two days following low-dose rituximab treatment. Other neurological symptoms improved within two weeks of rituximab treatment. At the 6-month follow-up, all neurological symptoms steadily improved with steroid reduction, and both the anti-CNTN1 antibody titer and CD19+ B cells steadily decreased. No adverse events were observed after this single low-dose rituximab treatment.

Conclusions

We confirmed the clinical efficacy of low-dose rituximab by B cell depletion in autoimmune nodopathy with anti-CNTN1 antibody. This rapid and long-lasting response suggests that low-dose rituximab is a promising option for anti-CNTN1 nodopathy.

Steroid therapy still plays a crucial role and could serve as a bridge to the next promising treatments in patients with IgG4-related sclerosing cholangitis: Results of a Japanese Nationwide Study

OBJECTIVE

The acceptable duration of steroid therapy for patients with IgG4-sclerosing cholangitis (SC) has been under debate. Our aim is to clarify the feasible duration of steroid treatment.

DESIGN

We retrospectively reviewed the data of patients with IgG4-SC and analyzed the following: biliary status during the steroid therapy, incidence of remission, relapse, relapse-free survival rate, and steroid-related complications (SRCs).

RESULTS

Remission was achieved 99.5% (763/767) of patients who received steroid therapy, while remission rate dropped to 63.6% (78/129) of patients who didn't receive it. Relapse was noted in 19.7% (151/763) of the patients who received steroid. Besides, relapse rate went up 38.4% (30/78) of the counterpart. Normalization of the serum total bilirubin and serum alkaline phosphatase (ALP) levels were achieved at two weeks regardless of biliary drainage. Multivariate analysis identified younger onset, MST less than three years, immunosuppressant, and steroid cessation as independent risk factors for relapse. Steroid-free was achieved in the patients underwent MST only 3.4% over 54 months. SRCs were recorded in a total of 99 patients (12.9%) despite sufficient preemptive medications. Multivariate analysis identified history of malignancy and immunosuppressant as independent risk factors for SRCs.

CONCLUSION

Steroid therapy should be continued for no less than three years to reduce the risk of relapse, with use of preemptive measures taken around five years. The biliary drainage might not be mandatory. Steroid as 1st line therapy could serve as a bridge to further promising treatments.

Autoimmune Neurological Disorders with IgG4 Antibodies: a Distinct Disease Spectrum with Unique IgG4 Functions Responding to Anti-B Cell Therapies

The main IgG4 antibody-mediated neurological disorders (IgG4-ND) include MuSK myasthenia; CIDP with nodal/paranodal antibodies to Neurofascin-155, contactin-1/caspr-1, or pan-neurofascins; anti-LGI1 and CASPR2-associated limbic encephalitis, Morvan syndrome, or neuromyotonia; and several cases of the anti-IgLON5 and anti-DPPX-spectrum CNS diseases. The paper is centered on the clinical spectrum of IgG4-ND and their immunopathogenesis highlighting the unique functional effects of the IgG4 subclass compared to IgG1-3 antibody subclasses. The IgG4 antibodies exert pathogenic effects on their targeted antigens by blocking enzymatic activity or disrupting protein-protein interactions affecting signal transduction pathways, but not by activating complement, binding to inhibitory FcγRIIb receptor or engaging in cross-linking of the targeted antigen with immune complex formation as the IgG1-IgG3 antibody subclasses do. IgG4 can even inhibit the classical complement pathway by affecting the affinity of IgG1-2 subclasses to C1q binding. Because the IgG4 antibodies do not trigger inflammatory processes or complement-mediated immune responses, the conventional anti-inflammatory therapies, especially with IVIg, immunosuppressants, and plasmapheresis, are ineffective or not sufficiently effective in inducing long-term remissions. In contrast, aiming at the activated plasmablasts connected with IgG4 antibody production is a meaningful therapeutic target in IgG4-ND. Indeed, data from large series of patients with MuSK myasthenia, CIDP with nodal/paranodal antibodies, and anti-LGI1 and CASPR2-associated syndromes indicate that B cell depletion therapy with rituximab exerts long-lasting clinical remissions by targeting memory B cells and IgG4-producing CD20-positive short-lived plasma cells. Because IgG4 antibody titers seem reduced in remissions and increased in exacerbation, they may serve as potential biomarkers of treatment response supporting further the pathogenic role of self-reacting B cells. Controlled trials are needed in IgG4-ND not only with rituximab but also with the other anti-B cell agents that target CD19/20, especially those like obexelimab and obinutuzumab, that concurrently activate the inhibitory FcγRIIb receptors which have low binding affinity to IgG4, exerting a more prolonged anti-B cell action affecting also antigen presentation and cytotoxic T cells. Antibody therapies targeting FcRn, testing those anti-FcRn inhibitors that effectively catabolize the IgG4 antibody subclass, may be especially promising.

A rare case of IgG4-related disease masquerading as periurethral malignancy and review of the literature

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory disease that typically manifests as mass lesions affecting almost any organ including the pancreas, lacrimal and salivary glands, liver, lung and kidney. However, IgG4-RD with urethra involvement is scarce. We describe a rare case of IgG4-RD involving the urethra mimicking urethral carcinoma and review the published literature. A 64-years-old female presented with progressive dysuria for more than 2 months. Pelvic gadolinium-enhanced magnetic resonance imaging revealed a huge mass encasing the urethra which showed obvious enhancement in the arterial phase. And contrast-enhanced ultrasound showed that the entire mass was heterogeneously enhanced and displayed a fast-forward and fast-out pattern, which was highly suggestive of malignant tumor. The diagnosis of IgG4-RD was finally established by ultrasound-guided transvaginal mass needle biopsy. The patient was treated with methylprednisolone and cyclophosphamide and dysuria disappeared in the first week of therapy. She has been followed up in our clinic for 1 year without recurrence. The diagnosis of IgG4-RD should be considered in the differential diagnosis of a periurethral mass. Ultrasound-guided transvaginal mass needle biopsy is a safe and well-established tissue sampling method and should be performed in order to avoid unnecessary surgery.

IgG4-Mediated Neurologic Autoimmunities: Understanding the Pathogenicity of IgG4, Ineffectiveness of IVIg, and Long-Lasting Benefits of Anti-B Cell Therapies

BACKGROUND AND OBJECTIVES

Describe the unique functions of immunoglobulin G4 (IgG4) in IgG4-neurologic disorders (IgG4-ND) and explain why, in contrast to their IgG1-counterparts, they respond poorly to intravenous immune globulin (IVIg) but effectively to anti-B cell therapies.

METHODS

The IgG4 structure and isotype switch, B cells and plasmablasts relevant to IgG4 production, and IgG4-induced disruption of the targeted antigens are reviewed and compared with IgG1-mediated autoimmune ND, where IVIg inhibits IgG1-triggered inflammatory effects.

RESULTS

The main IgG4-ND include muscle-specific kinase myasthenia; nodal/paranodal chronic inflammatory demyelinating polyradiculoneuropathy with antibodies to neurofascin-155, contactin-1/caspr-1, or pan-neurofascins; antileucine-rich, glioma-inactivated-1 and contactin-associated protein-like 2 associated-limbic encephalitis, Morvan syndrome, or neuromyotonia; and anti-IgLON5 disorder. The IgG4, because of its unique structural features in the hinge region, has noninflammatory properties being functionally monovalent and bispecific, unable to engage in cross-linking and internalization of the targeted antigen. In contrast to IgG1 subclass which is bivalent and monospecific, IgG4 does not activate complement and cannot bind to inhibitory Fcγ receptor (FcγRIIb) to activate cellular and complement-mediated immune responses, the key functions inhibited by IVIg. Because IVIg contains only 0.7%-2.6% IgG4, its idiotypes are of IgG1 subclass and cannot effectively neutralize IgG4 or sufficiently enhance IgG4 catabolism by saturating FcRn. In contrast, rituximab, by targeting memory B cells and IgG4-producing CD20-positive short-lived plasma cells, induces long-lasting clinical benefits.

DISCUSSION

Rituximab is the preferred treatment in IgG4-ND patients with severe disease by effectively targeting the production of pathogenic IgG-4 antibodies. In contrast, IVIG is ineffective because it inhibits immunoinflammatory functions irrelevant to the mechanistic effects of IgG4 and contains IgG-1 idiotypes that cannot sufficiently neutralize or possibly catabolize IgG4. Controlled studies with anti-CD19/20 monoclonals that also activate FcγRIIb may be more promising in treating IgG4-ND.

Rituximab as Maintenance Therapy in Type 1 Autoimmune Pancreatitis: An Italian Experience

OBJECTIVE

Rituximab (RTX) has been proposed for the induction of remission and maintenance therapy in relapsing type 1 autoimmune pancreatitis (AIP). The aim of the study was to describe the use of RTX as maintenance therapy for patients with type 1 AIP.

METHODS

Patients with type 1 AIP based on the International Consensus Diagnostic Criteria and treated with RTX were selected from our database. Two doses of RTX (1000 mg each) were administered 15 days apart and repeated after 6 months.

RESULTS

Eighteen patients were treated with RTX as maintenance therapy. Of these, the involvement of other organs was observed in 16 patients (89%). Eight of the 18 patients (44%) relapsed during follow-up. Median time to relapse after the last infusion was 30 months (range, 12-35 months). No disease relapse was observed in the first year after the last infusion. Probability of disease relapse was 80% between 1 and 3 years from initial treatment. No adverse effects were observed.

CONCLUSIONS

Rituximab seems be safe and effective for maintenance therapy of type 1 AIP during the first year after completing RTX infusion. However, the probability of disease relapse is high within 1 and 3 years from the last infusion.

Efficacy and safety of rituximab in autoimmune pancreatitis type 1: our experiences and systematic review of the literature

INTRODUCTION

Autoimmune pancreatitis (AIP) is a special form of pancreatitis that responds well to glucocorticoid (GC) treatment. Relapses of AIP are common. The anti-CD20 antibody rituximab (RTX) has shown promising results in GC refractory cases, but long-term data are scarce. The study aims to determine the clinical and imaging response to RTX and summarize the existing data on RTX therapy in patients with AIP type 1 in the literature.

PATIENTS AND METHODS

Retrospective analysis of electronic medical records was conducted. Additionally, we conducted a systematic review of the literature concerning RTX use in AIP type 1.

RESULTS

Twelve (11.7%) of 103 patients with AIP type 1 were treated with RTX during the study period: eight (66.7%) achieved complete and four (33.3%) partial remission. RTX was discontinued in one patient who developed fever and reactivation of latent tuberculosis. None of the remaining 11 patients relapsed during a median follow-up of 17 months. No significant differences were detected in baseline clinical characteristics or history of relapse between the patients who obtained complete and partial remission. Altogether, eight studies with 110 AIP type-1 patients treated with RTX were analyzed. Adverse effects ranged from 11-43% and the relapse-free period during follow-up (range 2-173 months) ranged from 38-94%.

CONCLUSIONS

Our results confirm that RTX is efficacious in the treatment of AIP type 1 by inducing remission and preventing relapse. In addition, there are few adverse effects of the treatment.

Efficacy and safety of rituximab for IgG4-related pancreato-biliary disease: A systematic review and meta-analysis

BACKGROUND

Type I autoimmune pancreatitis (AIP) and IgG4-related sclerosing cholangitis (IgG4-SC) belong to the IgG4-related disease (IgG4-RD) spectrum. Both entities respond to glucocorticoids, but iatrogenic toxicity associated with prolonged steroid therapy and relapse represent relevant clinical concerns in the long-term. Rituximab is increasingly used as an effective alternative strategy to induce remission but data regarding the safety and efficacy of B-cell depletion therapy for pancreato-biliary involvement of IgG4-RD are limited. We performed a systematic review and meta-analysis to estimate the rate of remission, flare, and adverse events (AEs) occurring in pancreato-biliary IgG4-RD following rituximab treatment.

METHODS

The MEDLINE, SCOPUS, and EMBASE databases were searched from inception to December 2020 to identify studies reporting the outcomes of IgG4-related pancreato-biliary disease after treatment with rituximab. Studies involving ≥2 patients were selected. In case of duplicated studies, the most recent or the one with the biggest N were chosen. The study was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Pooled effects were calculated using a random-effect model and expressed in terms of pooled remission, relapse, and AEs rates.

RESULTS

Seven cohort studies met inclusion criteria and 101 patients were included. Reasons for rituximab administration were new disease onset (18.5%), disease flare after glucocorticoids (63.5%), and glucocorticoids intolerance (17.9%). The median follow-up time was 19 months. The pooled rate of complete response at 6 months was 88.9% (95%CI 80.5-93.9) with no heterogeneity (I² = 0%). The pooled estimate of relapse rate was 21% (95%CI 10.5-40.3) with moderate heterogeneity (I² = 51%). A higher rate of relapse (35.9%, 95%CI 17.3-60.1) was reported in studies including patients with multiorgan involvement (OOI). The median time to relapse was 10 months. The pooled estimate of rituximab-related AEs was 25% (95%CI 8.8-53) with substantial heterogeneity (I² = 73.6%). No publication bias was observed.

CONCLUSION

Treatment of IgG4-related pancreato-biliary disease with rituximab is associated with high remission rate, a higher relapse rate in the presence of OOI, and limited AEs. Randomized controlled trials with adequate power are needed to confirm these findings.

Clinical Usefulness of Serum Autotaxin for Early Prediction of Relapse in Male Patients with Type 1 Autoimmune Pancreatitis

BACKGROUND

Serum IgG4 level is a useful diagnostic marker for autoimmune pancreatitis (AIP), but it is difficult to use to predict relapse.

AIMS

We investigated whether serum autotaxin (ATX) level is predictive of AIP relapse after steroid therapy.

METHODS

Fifty-six patients with type 1 AIP were investigated. We measured serum ATX at the time of diagnosis. We selected 24 males for whom serum samples during steroid therapy had been obtained and measured serum ATX at steroid therapy for induction of remission and at maintenance therapy. In the relapse group, we also measured ATX at the time of relapse.

RESULTS

ATX was significantly higher in female patients than in male patients. In order to clarify changes in ATX during steroid therapy, we focused on 24 male patients. We found that ATX decreased significantly during steroid therapy for induction of remission and at the time of maintenance therapy. In half of all patients who relapsed during maintenance therapy, ATX was significantly elevated at the time of relapse compared with that of induction therapy (P = 0.039). When we compared ATX at the time of maintenance therapy between patients with relapse and without, we observed significantly higher ATX in the former (P = 0.024). We found that the combination of ATX and elastase-1 could predict relapse with high accuracy (95%).

CONCLUSIONS

Preliminary evidence suggests that serum ATX might serve as a candidate biomarker to predict relapse of AIP as well as to monitor the effect of steroid therapy.

Emerging therapy options for IgG4-related disease

INTRODUCTION

Awareness of IgG4-related disease (IgG4-RD) is increasing worldwide and specialists are now familiar with most of its clinical manifestations and mimickers. IgG4-RD promptly responds to glucocorticoids and repeated courses are typically used to induce and maintain remission because the disease relapses in most patients. If left untreated, it can lead to organ dysfunction, organ failure and death. Advancement in our understanding of IgG4-RD pathogenesis is leading to the identification of novel therapeutic targets and emerging treatments are now setting the stage for personalized therapies for the future.

AREAS COVERED

This review focuses on emerging treatment options for IgG4-RD based on our advancing understanding of disease pathophysiology. Research was performed in the English literature on Pubmed and clinicaltrials.gov databases.

EXPERT OPINION

Glucocorticoids remain the first-line induction treatment for the multi-organ manifestations of IgG4-RD. Alternative immunosuppressive agents for maintaining remission are warranted in order to avoid long-term steroid toxicity, and to offer a more mechanistic and personalized therapeutic strategy. Targeting B and T-lymphocyte activation represents the most promising approach, but randomized controlled trials are eagerly awaited to confirm positive preliminary experiences reported in case series and small cohort studies.

A Follow-Up Study of a European IgG4-Related Disease Cohort Treated with Rituximab

OBJECTIVES

IgG4-related disease (IgG4-RD) is a chronic fibro-inflammatory disorder affecting virtually any organ. Type 1 autoimmune (type 1 AIP) is its pancreatic manifestation. To date, steroids are considered the first-line pancreatitis treatment. The CD20-binding antibody rituximab (RTX) appears a promising steroid-sparing therapy, although long-term data are lacking. We aimed to bridge this gap with a cohort of IgG4-RD patients treated with RTX and to assess the potential value of the Responder Index (RI) as a discriminatory score for disease activity.

METHODS

We retrospectively evaluated 46 patients from a tertiary referral centre who were diagnosed with IgG4-RD and/or type 1 AIP according to the International Consensus Diagnostic Criteria or Unifying-AIP criteria between June 2006 and August 2019.

RESULTS

Patients resembled previous cohorts in terms of characteristics, diagnosis, and therapeutic response. Thirteen of the 46 patients with IgG4-RD/type 1 AIP were treated with RTX pulse therapy due to relapse, adverse reactions to steroids, or high-risk constellations predicting a severe course of disease with multi-organ involvement. Median follow-up after diagnosis was 52 months for all subjects, and 71 months in IgG4-RD patients treated with RTX. While patients in the RTX group showed no significant response to an initial steroid pulse, clinical activity as measured by the RI significantly decreased in the short-term after RTX induction. Within 16 months, 61% of patients relapsed in the RTX group but responded well to re-induction. Clinical and laboratory parameters improved equally in response to RTX.

CONCLUSION

RTX therapy in patients with IgG4-RD is an effective and safe treatment to induce treatment response and possible long-term remission. Repeated RTX administration after 6-9 months may be of value in reducing the risk of relapse. The RI appears to be a reasonable index to assess disease activity and to identify patients with IgG4-related disease who may benefit from B-cell-depleting therapy.

Successful treatment of IgG4-related hypertrophic pachymeningitis with induction rituximab and dexamethasone followed by maintenance rituximab

IgG4-related disease (IgG4RD) with intracranial involvement is rare. We report a 56-year-old male who had an excellent response to rituximab and dexamethasone after going undiagnosed for 5 years. After 3 years of rituximab maintenance, he has no evidence of disease on brain MRI.

Clinical characteristics of IgG4-related retroperitoneal fibrosis versus idiopathic retroperitoneal fibrosis

Retroperitoneal fibrosis (RPF) is an uncommon condition characterized by inflammation and fibrosis in the retroperitoneal space. More than two-thirds of RPF are idiopathic, with the remaining stemed from a variety of secondary causes. It was suggested that IgG4-related RPF is a secondary form of RPF. We undertook this study to compare detailed demographic, clinical and laboratory characteristics of IgG4-related RPF and IRPF in a large Chinese cohort. We retrospectively reviewed the medical records of 132 RPF patients diagnosed at Peking University People’s Hospital between March 2010 and March 2018. Among the 132 patients, the mean age at disease onset was 54.8 years. IgG4-related RPF group showed greater male predominance compared to IRPF group. IgG4-related RPF patients showed a longer interval between symptom onset and diagnosis, and allergic diseases were more common in this group. Sixty-four patients (48.4%) had lower back pain, which was more common in IRPF group than that in IgG4-related RPF patients. In terms of organ involvement, although 42 of 47 patients (89.3%) with IgG4-related RPF had other organ involvement, there were no patients in the IRPF group with other organ involvement. In addition, the serum IgG4 level, elevated eosinophils counts and IgE level were significantly higher in IgG4-related RPF patients. We described the demographic, clinical and laboratory differences between IgG4-related RPF and IRPF patients, indicating their potential differences in pathogenesis, which was of great importance to diagnose and manage the two phenotypes.

B cell targeted therapy for immunoglobulin G4-related disease

Glucocorticoids are the first-line drug for the remission induction therapy of immunoglobulin (Ig) G4-related disease. Achieving drug-free remission using glucocorticoids alone is difficult, however, and many patients require maintenance therapy with glucocorticoids and immunosuppressants. Studies have recently found that the number of peripheral memory B cells and plasmablasts is increased in IgG4-related disease and have indicated the efficacy of rituximab, which, in remission induction therapy, rapidly reduces serum IgG4 levels and has the tapering effect of glucocorticoids. Rituximab has been shown to reduce the risk of relapse more than oral immunosuppressants such as azathioprine. However, maintaining drug-free remission is difficult with a single course of rituximab alone, and many cases require maintenance therapy with rituximab. This article outlines the potential of B-cell targeted therapy, focusing on the efficacy, and safety of rituximab for IgG4-related disease.

Relapse predictors and serologically unstable condition of IgG4-related disease: a large Chinese cohort

OBJECTIVES

Patients with IgG4-related disease (IgG4-RD) typically respond well to initial glucocorticoid therapy, but always relapse with tapered or maintenance dosage of steroid. We aimed to identify the risk factors for relapse of IgG4-RD and explore the impact of active intervention on the serologically unstable condition.

METHODS

We performed a retrospective study of 277 IgG4-RD patients at Peking University People's Hospital from February 2012 through February 2019. They were all followed for >4 months. The primary outcome was patient relapse. Data on recurrence of IgG4-RD symptoms, laboratory and image findings were recorded, along with information on treatment in the serologically unstable condition.

RESULTS

The cumulative relapse rate was 12.86%, 27.84% and 36.1% at 12, 24 and 36 months, respectively. Younger age at onset, younger age at diagnosis, longer time from diagnosis to treatment and history of allergy were associated with relapse. Identified independent risk factors were longer time from diagnosis to treatment and history of allergy. When serum IgG4 level was 20%, 50% or 100% higher than that of the remission period, similar percentages of patients finally relapsed, regardless of whether they were in the immunosuppression intensified or non-intensified group. Median duration from serum IgG4 level instability to relapse in the intensified and non-intensified group was not statistically different.

CONCLUSION

The risk factors of relapse were longer time from diagnosis to treatment and history of allergy. Intervention in the serologically unstable condition was not helpful for reducing relapse rate.

Autoimmune pancreatitis: Current perspectives

Over the last two decades, our knowledge and understanding regarding the pathogenesis and biology of autoimmune pancreatitis (AIP) have improved tremendously. Type 1 AIP or IgG4-related pancreatitis (IgG4-RP) is now believed to be the prototype of the multisystemic IgG4-related disease. In view of clinical features like obstructive jaundice and mass-forming lesions in the pancreas in elderly men, type 1 AIP often mimics pancreatic cancer. IgG4-related sclerosing cholangitis concomitantly involving the extrahepatic and intrahepatic biliary tree is the most common extrapancreatic involvement seen in up to 80% of these patients, which needs to distinguish from cholangiocarcinoma. Histology is characterised by lymphoplasmacytic inflammation, abundant IgG4 positive plasma cell infiltration, storiform fibrosis and obliterative phlebitis. Apart from histology, high serum IgG4 levels, pancreatic parenchymal and duct imaging findings and other organ involvement aid in diagnosis especially in cases where definitive histology is not evident. Also, these parameters lay the foundation of various diagnostic criteria proposed over last few years. On the contrary, histology alone is the mainstay for establishing diagnosis of idiopathic duct-centric pancreatitis (IDCP) as it lacks any specific serological marker or imaging. Since both types of AIP respond dramatically to corticosteroid treatment, a biopsy is crucial to establish the preoperative diagnosis and to exclude malignancy so as to avoid unnecessary surgery. This review discusses the morphologic spectrum, treatment and prognosis of IgG4-RP and IDCP with an emphasis on approach to diagnosis with relevant histologic features, differential diagnoses and the challenges faced during biopsy interpretation.

The long-term outcomes of patients with immunoglobulin G4-related sclerosing cholangitis: the Mayo Clinic experience

BACKGROUND

The long-term outcomes of immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) are not well known.

METHODS

The outcomes of patients with IgG4-SC at Mayo Clinic (1999-2018) were compared to an age- and gender-matched (1:1 ratio) group of patients with primary sclerosing cholangitis (PSC).

RESULTS

We identified 89 patients with IgG4-SC; median age at diagnosis was 67 years, 81% were males, and the median follow-up was 5.7 years. Seventy-eight patients received prednisone for induction of remission, and 53 received at least one other immunosuppressive agent for maintenance of remission. Of the IgG4-SC group, 10 died (median time from diagnosis until death was 6.5 years): 2 due to cirrhosis, 3 due to cholangiocarcinoma (CCA), and 5 due to non-hepatobiliary causes. Eleven patients in the PSC group underwent liver transplantation, while none did in the IgG4-SC group. The incidence of a hepatobiliary adverse event (cirrhosis or CCA) was 3.4 times greater in the PSC compared to the IgG4-SC group (events per 1000 person-years: 52.6; 95% CI 38-73; vs. 15.6; 95% CI 7-32). The probability of development of a hepatobiliary adverse event within 10 years was 11% in the IgG4-SC compared to 45% in the PSC group (P = 0.0001). The overall survival tended to be higher in the IgG4-SC compared to the PSC group (10-year: 79% vs. 68%, respectively; P = 0.11).

CONCLUSIONS

In a cohort of IgG4-SC patients, 88% of whom were treated with immunosuppressive drugs, the risk of cirrhosis and CCA was significantly lower compared to an age- and gender-matched group with PSC.

Advances in the diagnosis and management of IgG4 related disease

IgG4 related disease was recognized as a unified disease entity only 15 years ago. Awareness of IgG4 related disease has increased worldwide since then, and specialists are now familiar with most of its clinical manifestations. Involvement of the pancreato-biliary tract, retroperitoneum/aorta, head and neck, and salivary glands are the most frequently observed disease phenotypes, differing in epidemiological features, serological findings, and prognostic outcomes. In view of this multifaceted presentation, IgG4 related disease represents a great mimicker of many neoplastic, inflammatory, and infectious conditions. Histopathology remains key to diagnosis because reliable biomarkers are lacking. Recently released classification criteria will be invaluable in improving early recognition of the disease. IgG4 related disease is highly treatable and responds promptly to glucocorticoids, but it can lead to end stage organ failure and even death if unrecognized. Prolonged courses of corticosteroids are often needed to maintain remission because the disease relapses in most patients. Rapid advancement in our understanding of the pathophysiology of IgG4 related disease is leading to the identification of novel therapeutic targets and possible personalized approaches to treatment.

Long-term efficacy of maintenance therapy with Rituximab for IgG4-related disease

BACKGROUND

IgG4-Related Disease (IgG4-RD) promptly responds to glucocorticoids but relapses in most patients. Rituximab (RTX) represents a promising strategy to avoid IgG4-RD flares but its administration for maintaining disease remission has never been assessed in terms of optimal timing of infusion, dosage, and duration of treatment. In the present study we aimed to evaluate the efficacy and safety of RTX for maintenance of IgG4-RD remission.

METHODS

Fourteen patients with IgG4-RD were treated with RTX as induction of remission therapy at the San Raffaele Scientific Institute in Milan, Italy. The cohort was then divided into two study groups: patients re-treated only in case of disease relapse (Group 1, n = 7), and patients regularly re-treated with RTX every 6 months for maintenance therapy (Group 2, n = 7). Data on free-relapse rate and adverse events were collected and retrospectively analysed.

RESULTS

Median follow-up time and baseline clinical-serological features were similar between Group 1 and 2 (p > 0.05). The free relapse rate 18 months after induction of remission treatment was significantly lower in Group 1 (29%) than in Group 2 (100%) (p = 0.006). Infectious complications developed in 6/14 patients (3 in Group 1 and 3 in Group 2).

CONCLUSION

Administration of RTX every 6 months as maintenance of remission therapy prevents IgG4-RD flares.

Immunoglobulin G4-related Disease

Immunoglobulin G4 (IgG4)-Related Disease (IgG4-RD) can cause fibroinflammatory lesions in nearly any organ and lead to organ dysfunction and irreversible damage. In addition to frequent involvement of the salivary glands, lacrimal glands, and/or pancreas, IgG4-RD often affects the chest. Thoracic manifestations include lung nodules and consolidations, pleural thickening, aortitis, and lymphadenopathy. The diagnosis is made after careful clinicopathologic correlation because there is no single diagnostic test with excellent sensitivity or specificity. Biopsy of pulmonary lesions can be useful for distinguishing IgG4-RD from common mimickers. Immunosuppressive regimens, such as glucocorticoids and/or glucocorticoid-sparing agents, form the cornerstone of treatment.

Disease Severity Linked to Increase in Autoantibody Diversity in IgG4-Related Disease

OBJECTIVE

Four autoantigens have been described recently in IgG4-related disease (IgG4-RD): prohibitin, annexin A11, laminin 511-E8, and galectin-3. However, no external validation has been performed, and the possibility that some individuals break tolerance to more than 1 autoantigen has not been explored. We undertook this study to evaluate the relative frequencies of antibody responses against these autoantigens in order to explore the role of adaptive immune response in IgG4-RD.

METHODS

Autoantibody responses against prohibitin, annexin A11, and laminin 511-E8 were measured among a clinically diverse cohort of IgG4-RD patients (n = 100) using enzyme-linked immunosorbent assays. Autoantibody responses were correlated with disease severity and organ distribution.

RESULTS

The frequencies of IgG4 autoantibody responses against prohibitin (10%), annexin A11 (12%), and laminin 511-E8 (7%) were not significantly different from those of controls. A portion of the cohort (n = 86) had been analyzed previously at our center for anti-galectin-3 antibody responses, with 25 patients (29%) having IgG4 anti-galectin-3 antibodies. Of these 86 patients, 32 (37%) had IgG4 antibodies to ≥1 of the 4 autoantigens and 12 (14%) showed reactivity with ≥2 of the tested antigens. The subset of patients with ≥2 autoantibodies had higher total levels of IgG1, IgG2, IgG4, and C-reactive protein, were more commonly hypocomplementemic, and were more likely to have visceral organ involvement.

CONCLUSION

Antibodies against prohibitin, annexin A11, and laminin 511-E8 were found in only a small portion of patients with IgG4-RD. A subset of IgG4-RD patients, however, had IgG4 antibodies against ≥2 autoantigens. These patients presented with robust IgG subclass elevations, complement consumption, and visceral organ involvement. This broader break in immunologic tolerance in IgG4-RD was associated with more severe disease.

Efficacy and safety of iguratimod on patients with relapsed or refractory IgG4-related disease

OBJECTIVE

To evaluate the therapeutic efficacy and safety of iguratimod on patients with relapsed or refractory IgG4-related disease (IgG4-RD).

METHODS

We conducted a retrospective single-center study in 17 IgG4-RD patients admitted to Peking University People's Hospital. Patients were given iguratimod, 25 mg, twice daily and clinical data were collected at 0, 12, and 24 weeks. The baseline treatments include prednisone, cyclophosphamide, leflunomide, mycophenolate mofetil, and methotrexate. Clinical manifestation, IgG4-RD responder index (IgG-RD RI), serological indexes, gland ultrasound findings, and adverse drug effect were recorded. IgG4-RD RI scores < 3 and declining ≥ 2 were recognized as complete response (CR); IgG4-RD RI scores declining ≥ 2 but remaining ≥ 3 were recognized as partial response (PR). If a patient's IgG4-RD RI score was 3 at the beginning, PR was considered as a 1-point decrease after the therapy.

RESULTS

Serum IgG4 decreased significantly from 708 (321-902) mg/dl at baseline to 446 (138-396) mg/dl at 24 weeks (P = 0.0016). IgG4-RD RI decreased significantly from 9.79 ± 3.07 at baseline to 3.57 ± 1.09 at 24 weeks (P < 0.0001). Overall, 2 (14.3%) patients achieved CR, 11 (78.6%) patients achieved PR, and 1 (7.14%) patient had no response to treatment at week 24. Serum IgG level and salivary glands major diameter also decreased significantly at week 12 and 24 after treatment.

CONCLUSION

Iguratimod can be a therapeutic strategy to achieve remission in relapsed or refractory IgG4-RD patients inadequately responding to corticosteroid treatment with or without other immunosuppressant treatment. Key messages • Iguratimod was effective for relapsed or refractory IgG4-RD patients. • Iguratimod can improve the clinical symptoms of patients, reduce the serum IgG and IgG4 levels, and can also reduce the volume of involved glands.

Glucocorticoids and steroid sparing medications monotherapies or in combination for IgG4-RD: a systematic review and network meta-analysis

Objective

To assess the safety and efficacy of glucocorticoids (GCs), immunosuppressive agents (IM) and rituximab (RTX), alone or in combination, for the treatment of IgG4-RD.

Methods

Relevant articles published were searched in the databases with relevant key words. Network meta-analysis was conducted, with various outcomes including relapse rate, remission rate and adverse events. Data were calculated with odds ratio (ORs) and 95% CI. P-score was used to rank the treatments.

Results

A total of 15 studies involving 1169 patients were included. Network meta-analysis indicated that RTX maintenance therapy had the lowest relapse rate of all treatments (OR = 0.10, 95% CI [0.01, 1.63]), whereas GCs + IM was associated with a lower relapse rate compared with GCs alone (OR = 0.39, 95% CI [0.20, 0.80]). Further, patients treated with GCs + IM had a higher remission rate than those given GCs (OR= 3.36, 95% CI [1.44, 7.83]), IM (OR= 55.31, 95% CI [13.73, 222.73]) monotherapies or RTX induction therapy only (OR= 7.38, 95% CI [1.56, 34.94]). The rate of adverse events was comparable among the different treatment groups.

Conclusion

Treatment of IgG4-RD patients with GCs and IM was associated with higher remission rates and lower relapse rates, as well as comparable safety profiles compared with GC, IM and RTX induction therapy. RTX maintenance therapy had a larger reduction in the relapse rate compared with GC and IM. The current evidence should be carefully scrutinized as the included studies were observational in design. Larger randomized controlled trials are needed to confirm.

Gastrointestinal and Extra-Intestinal Manifestations of IgG4-Related Disease

IgG4-related disease (IgG4-RD) is a chronic relapsing multi-organ fibro-inflammatory syndrome of presumed autoimmune etiology. It is characterized by increased serum levels of IgG4 and tissue infiltration by IgG4⁺ cells. Increased titers of autoantibodies against a spectrum of self-antigens and response to steroids have led to its characterization as an autoimmune disease. However, the pathognomonic antigens probably differ among manifestations, and different antigens or autoantibodies produce similar immune reactions in different organs. Little is known about the pathogenic effects, if any, of serum IgG4 or IgG4⁺ plasma cells in tissues. Despite several animal models of the disease, none truly recapitulates human IgG4-RD. Histologic analyses of tissues from patients with IgG4-RD reveal a dense lymphoplasmacytic infiltrate rich in IgG4⁺ plasma cells, storiform fibrosis, and obliterative phlebitis, although these features vary among organs. Typical presentation and imaging findings include mass-forming synchronous or metachronous lesions in almost any organ, but most commonly in the pancreas, bile duct, retroperitoneum, kidneys, lungs, salivary and lacrimal glands, orbit, and lymph nodes. In all organs, inflammation can be reduced by corticosteroids and drugs that deplete B cells, such as rituximab. Patients with IgG4-RD have relapses that respond to primary therapy. Intense fibrosis accompanies the inflammatory response, leading to permanent organ damage and insufficiency. Death from IgG4-RD is rare. IgG4-RD is a multi-organ disease with predominant pancreatico-biliary involvement. Despite its relapsing-remitting course, patients have an excellent prognosis.