Histopathological and immunophenotypic features of ipilimumab-associated colitis compared to ulcerative colitis

Autoimmune complications of tyrosine kinase inhibitors in cancer therapy: Clinical insights, mechanisms, and future perspectives

The tyrosine kinase inhibitors (TKIs) have emerged as a promising class of novel anticancer drugs, achieving significant success in clinical applications. However, the risk of autoimmune diseases associated with these drugs has raised widespread concerns. In this review, TKI-induced autoimmune diseases are reviewed in order to understand this complex phenomenon through clinical research and molecular mechanism exploration. Despite the relatively low incidence of autoimmune diseases, their potential severity demands heightened attention. The potential mechanisms underlying TKI-induced autoimmune diseases may involve immune system dysregulation, alterations in immune cell function, activation of inflammatory responses, and attacks on self-antigens. Various preventive strategies, including clinical monitoring, personalized treatment, optimization of therapeutic approaches, and patient education and communication, can be employed to effectively address these potential risks. Future research directions should delve into the molecular mechanisms of TKI-induced autoimmune diseases, integrate studies on genetics and immunogenetics, advance the development of novel TKIs, explore the possibilities of combining immunotherapy with TKI treatment, and propel large-scale clinical trials.

Histopathologic Features of Unmasked Inflammatory Bowel Disease Following Immune Checkpoint Inhibitor Therapy in Colon Biopsies

Background and Aims

Typical immune checkpoint inhibitor-induced colitis (T-ICI) has significant histomorphologic overlap with inflammatory bowel disease (IBD), a distinction further complicated in ICI-treated patients with pre-existing inflammatory bowel disease (P-IBD) and those with potentially "unmasked" inflammatory bowel disease (U-IBD) after ICI therapy. This study describes histopathologic findings seen in U-IBD colonic biopsies and assesses for distinguishing features from T-ICI and P-IBD biopsies.

Methods

Initial colon biopsies after symptom onset from 34 patients on ICI therapy were reviewed, and histopathologic features were tabulated. U-IBD patients were identified clinically based on rapid toxicity development post-ICI treatment with multiple recurrences after immune suppression, frequently with regional colitis (versus pancolitis).

Results

The study cohort was classified into T-ICI (n = 20), P-IBD (n = 9), and U-IBD (n = 5) groups. The predominant histological patterns were diffuse active colitis (35%) in the T-ICI, and chronic active colitis in both the P-IBD (67%) and U-IBD (60%) groups (overall P = .003, P > .05 between the two IBD groups). None of the T-ICI biopsies demonstrated chronicity features (ie, architectural distortion score 2, basal lymphoplasmacytosis, or Paneth cell metaplasia). Only U-IBD biopsies demonstrated basal lymphoplasmacytosis (60% vs 0% in T-ICI/P-IBD, P = .002). Among available follow-up biopsies, chronicity features were present in all (4/4) U-IBD patients, including those without chronicity seen in the initial biopsy, but none (0/7) of T-ICI patients.

Conclusion

These early results show that no definite features of chronicity were seen in colon biopsies from T-ICI patients, suggesting that the presence of those features may be a clue to U-IBD in patients without a known IBD diagnosis. Frequent basal lymphoplasmacytosis seen in U-IBD may support a recent onset of mucosal injury and early architectural remodeling.

Focus on Immune Checkpoint Inhibitors-related Intestinal Inflammation: From Pathogenesis to Therapeutical Approach

Recently, antitumor immunotherapies have witnessed a breakthrough with the emergence of immune checkpoint inhibitors (ICIs) including programmed cell death-1 (PD-1), programmed cell death-ligand 1 (PD-L1), and cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors. Unfortunately, the use of ICIs has also led to the advent of a novel class of adverse events that differ from those of classic chemotherapeutics and are more reminiscent of autoimmune diseases, the immune-related adverse events (IRAEs). Herein, we performed an insight of the main IRAEs associated with ICIs, focusing on gastroenterological IRAEs and specifically on checkpoint inhibitor colitis, which represents the most widely reported IRAE to date. We comprehensively dissected the current evidence regarding pathogenesis, diagnosis, and management of ICIs-induced colitis, touching upon also on innovative therapies.

Enterocolitis and other immunotherapy and targeted therapy-related gastrointestinal manifestations: A review for gastroenterologist

New oncologic treatments, particularly immunotherapy (IT), have revolutionized the treatment of advanced-stage malignant tumors. Immune checkpoint inhibitors are the main form of IT and act by increasing T cell activity and the organism's immune response against neoplastic cells. Targeted therapy is another form of IT that acts by inhibiting oncogenes or inflammation signaling and tumor angiogenesis pathways. However, these mechanisms of tumor destruction can interfere with the host's immune self-tolerance or with the mechanisms of epithelial tissue repair and predispose to immune system-mediated adverse events that can affect multiple organs, including the digestive tract. The gastrointestinal manifestations of damage caused by IT can range from low-grade mucositis to ulceration, and in some cases, necrosis and perforation. Any part of the gastrointestinal tract can be affected, but there is greater involvement of the small bowel and colon, with a pattern similar to that seen in inflammatory bowel disease. The most common clinical manifestation is chronic diarrhea. The differential diagnosis includes enteropathogenic infections, especially those caused by opportunistic microorganisms; adverse drug reactions; and other inflammatory and malabsorption disorders. Treatment is guided by damage severity. Mild cases can be treated with antidiarrheals and rehydration in the outpatient setting; moderate cases with hospitalization, systemic steroids, and temporary suspension of IT; and severe cases with immunosuppressants or biologic agents and definitive suspension of IT.

Histopathologic Manifestations of Immune Checkpoint Inhibitor Therapy-Associated Gastrointestinal Tract Injury: A Practical Review

Immune checkpoint inhibitors have revolutionized the management of many advanced cancers by producing robust remissions. They mostly target two immune regulatory pathways: cytotoxic T lymphocyte antigen-4 and programmed death-1 or its ligand. However, a flip side is the immune-related adverse events (irAEs) commonly affecting the gastrointestinal (GI) tract that can cause treatment interruptions or discontinuation. This practical review discusses the clinical and histopathologic findings of irAEs encountered in the luminal GI tract, along with histopathologic differentials that can mimic varied inflammatory, infectious, or other medication-associated etiologies and the importance of clinico-pathologic correlation for an accurate diagnosis.

Endocrine immune-related adverse effects of immune-checkpoint inhibitors

INTRODUCTION

Immune-checkpoint inhibitor therapy modulates the response of the immune system acting against cancer. Two pathways impacted by this kind of treatment are the CTLA4 and the PD-1/PD-L1 pathways. ICI therapy can trigger autoimmune adverse effects, known as immune-related Adverse Events (irAEs).

AREAS COVERED

This review focuses on irAEs which affect the endocrine system. This review elucidates the pathways used by these drugs with a focus on the hypothetical pathogenesis at their basis. In fact, the pathophysiology of irAEs concerns the possibility of an interaction between cellular autoimmunity, humoral immunity, cytokines, chemokines, and genetics. The endocrine irAEs examined are thyroid dysfunctions, immune related-hypophysitis, diabetes, peripheral adrenal insufficiency, and hypoparathyroidism.

EXPERT OPINION

There is still much to investigate in endocrine irAES of checkpoint inhibitors. In the future, checkpoint inhibitors will be increasingly utilized therapies, and therefore it is crucial to find the proper diagnostic-therapeutic program for irAEs, especially as endocrine irAEs are nonreversible and require lifelong replacement therapies.

Immune-mediated colitis associated with ocrelizumab: A new safety risk

BACKGROUND

An association between certain immunomodulatory therapies (rituximab, ipilimumab, and other immune checkpoint inhibitors) and inflammatory (non-ischemic and non-infectious) colitis in oncologic and non-oncologic patient populations is well documented in the medical literature.

OBJECTIVE

The purpose of this case series is to describe adverse event reports of new onset, inflammatory colitis in association with ocrelizumab in patients with multiple sclerosis submitted to U.S. Food and Drug Administration (FDA) or published in the medical literature.

METHODS

The FDA Adverse Event Reporting System (FAERS) and medical literature were searched.

RESULTS

A review of postmarketing cases from FAERS and published medical literature identified 38 cases consistent with inflammatory, non-ischemic, and non-infectious colitis in association with ocrelizumab. The median time-to-onset was 8 months. Cases were reported using the following diagnostic terms: Crohn's disease (13), unspecified colitis (11), microscopic colitis (5), ulcerative colitis (5), medication-induced colitis (3), and autoimmune colitis (2).

CONCLUSIONS

This case series highlights ocrelizumab induced immune-mediated colitis that can be clinically severe and potentially life-threatening. Based on the findings of this review, the ocrelizumab Prescribing Information was amended to include immune-mediated colitis in the Warnings and Precautions section.

Checkpoint Inhibitor-Induced Colitis: From Pathogenesis to Management

The advent of immunotherapy, specifically of immune checkpoint inhibitors (ICIs), for the treatment of solid tumors has deeply transformed therapeutic algorithms in medical oncology. Approximately one-third of patients treated with ICIs may de velop immune-related adverse events, and the gastrointestinal tract is often affected by different grades of mucosal inflammation. Checkpoint inhibitors colitis (CIC) presents with watery or bloody diarrhea and, in the case of severe symptoms, requires ICIs discontinuation. The pathogenesis of CIC is multifactorial and still partially unknown: anti-tumor activity that collaterally effects the colonic tissue and the upregulation of specific systemic inflammatory pathways (i.e., CD8+ cytotoxic and CD4+ T lymphocytes) are mainly involved. Many questions remain regarding treatment timing and options, and biological treatment, especially with anti-TNF alpha, can be offered to these patients with the aim of rapidly resuming oncological therapies. CIC shares similar pathogenesis and aspects with inflammatory bowel disease (IBD) and the use of ICI in IBD patients is under evaluation. This review aims to summarize the pathogenetic mechanism underlying CIC and to discuss the current evidenced-based management options, including the role of biological therapy, emphasizing the relevant clinical impact on CIC and the need for prompt recognition and treatment.

Position statement on the management of the immune checkpoint inhibitor-induced colitis via multidisciplinary modified Delphi consensus

INTRODUCTION

The use of immune checkpoint inhibitors (ICIs) in cancer immunotherapy has shown increased overall survival in a wide range of cancer types with the associated risk of developing severe immune-mediated adverse events, commonly involving the gastrointestinal tract.

AIM

The aim of this position statement is to provide an updated practice advice to the gastroenterologists and oncologists on the diagnosis and management of ICI-induced gastrointestinal toxicity.

METHODOLOGY

The evidence reviewed in this paper includes a comprehensive search strategy of English language publications. Consensus was reached using a three-round modified Delphi methodology and approved by the members of the Belgian Inflammatory Bowel Disease Research and Development Group (BIRD), Belgian Society of Medical Oncology (BSMO), Belgian group of Digestive Oncology (BGDO), and Belgian Respiratory Society (BeRS).

CONCLUSIONS

The management of ICI-induced colitis requires an early multidisciplinary approach. A broad initial assessment is necessary (clinical presentation, laboratory markers, endoscopic and histologic examination) to confirm the diagnosis. Criteria for hospitalisation, management of ICIs, and initial endoscopic assessment are proposed. Even if corticosteroids are still considered the first-line therapy, biologics are recommended as an escalation therapy and as early treatment in patients with high-risk endoscopic findings.

Checkpoint Inhibitor-Induced Colitis: An Update

Immunotherapy with immune checkpoint inhibitors (ICIs) nowadays has indications for several solid tumors. The current targets for ICIs are CTLA-4, PD-1, and PD-L1 receptors. Despite the clinical advantages derived from ICIs, a variety of side effects are linked to overstimulation of the immune system. Among these, ICI-related colitis is one of the most common, with a disabling impact on the patient. Diarrhea, abdominal pain, abdominal distension, cramping, and hematochezia are the most common ICI enterocolitis presenting symptoms. The most frequently used grading system for assessment of the severity of ICI enterocolitis is called the Common Terminology Criteria for Adverse Events (CTCAE) grading. With regard to the histological picture, there is no specific feature; however, microscopic damage can be classified into five types: (1) acute active colitis, (2) chronic active colitis, (3) microscopic colitis-like, (4) graft-versus-host disease-like, and (5) other types. Supportive therapy (oral hydration, a bland diet without lactose or caffeine, and anti-diarrheal agents) is indicated in mild colitis. Symptomatic treatment alone or with loperamide, a low-fiber diet, and spasmolytics are recommended for low-grade diarrhea. In more severe cases, corticosteroid treatment is mandatory. In refractory cases, off-label use of biological therapies (infliximab or vedolizumab) was proposed.

Gastrointestinal and Hepatobiliary Immune-related Adverse Events: A Histopathologic Review

Immune checkpoint inhibitors have been increasingly used to treat various malignant neoplasms. Despite their superior efficacy in treating certain ones, their global immune-activation effect leads to systemic side effects, referred to as immune-related adverse events. Immune-related adverse events affect a variety of organs, including the skin, gastrointestinal, hepatobiliary, and endocrine organs. Gastrointestinal tract immune-related adverse events present with a wide range of symptoms with variable severity, which may lead to treatment interruption and administration of immunosuppression therapy in many cases. Histopathologic changes are diverse, overlapping with many other conditions. Therefore, recognizing these changes is crucial in diagnosing immune-related adverse events. This review discusses the pathologic manifestations of gastrointestinal immune-related adverse events and discusses the primary differential diagnoses.

Immune Checkpoint Inhibitor Enterocolitis vs Idiopathic Inflammatory Bowel Disease

Immune checkpoint inhibitors have revolutionized management of advanced malignancies. However, their use is frequently complicated by immune related adverse events (irAEs), immune checkpoint inhibitor enterocolitis (IMEC) being the most common toxicity. IMEC is a distinct form of bowel inflammation that is highly reminiscent of idiopathic inflammatory bowel disorders (Crohn's disease, ulcerative colitis, and microscopic colitis). In this review, we highlight the similarities and differences in the pathophysiology, clinical presentation, evaluation, and management of these overlapping immune inflammatory bowel disorders. IMEC is an inflammatory bowel disease-like irAE that occurs as an outcome of disruption of intestinal immune surveillance and gut dysbiosis. Clinical and endoscopic presentation of both entities is strikingly similar, which often guides management. Though well established in inflammatory bowel disease, little is known about the long term outcomes of IMEC.

CD8+ Lymphocyte Infiltration Is a Specific Feature of Colitis Induced by Immune Checkpoint Inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICPIs) have revolutionized cancer therapy, although immune-related adverse events (irAEs) remain a serious issue. The clinical characteristics of colitis induced by ICPIs are very similar to inflammatory bowel disease. Recently, cluster of differentiation 8 positive (CD8⁺) lymphocyte infiltration into organs has been associated with the onset of irAEs. The present study compared the histological infiltration of CD8⁺ lymphocytes in irAE colitis with that in other colitis.

METHODS

Newly diagnosed and untreated patients were retrospectively enrolled. Biopsy specimens were obtained from endoscopic areas of high inflammation for immunohistochemical analysis of the number of cluster of differentiation 4 positive (CD4⁺) and CD8⁺ lymphocytes in the high-powered microscopic field with the most inflammation.

RESULTS

A total of 102 patients [12 with irAE colitis, 37 with ulcerative colitis (UC), 22 with Crohn's disease (CD), and 31 with ischemic colitis (IC)] were analyzed. In irAE colitis, CD8⁺ lymphocyte infiltration was significantly greater than that of CD4⁺ lymphocytes (p < 0.01). The amount of CD8⁺ lymphocyte infiltration was significantly higher in irAE colitis than in UC (p < 0.05), CD (p < 0.05), and IC (p < 0.01). The CD8⁺/CD4⁺ ratio was also significantly higher in irAE colitis (p < 0.01 versus UC, CD, and IC, respectively). The optimal cutoff CD8⁺/CD4⁺ ratio for diagnosing irAE colitis was 1.17 (sensitivity 83%, specificity 84%). The optimal cutoff number of CD8⁺ lymphocytes for diagnosing irAE colitis was 102 cells per high-power field (sensitivity 75%, specificity 81%).

CONCLUSIONS

Greater CD8⁺ lymphocyte infiltration and a higher CD8⁺/CD4⁺ ratio may be simple and useful biomarkers to distinguish irAE colitis from other forms of colitis.

Drug-induced digestive tract injury: decoding some invisible offenders

There is an ever-growing list of pharmacological agents, several of which are attributed to cause clinically significant gastrointestinal (GI) injury. Many patients present with significant but nonspecific symptoms, that in conjunction with the absence of relevant drug history on the requisition slip can make the histopathologic diagnosis challenging. To complicate this, although some drugs have relatively characteristic histopathologic features (such as doxycycline), there exist many other drugs that exhibit wide and varying spectra of histopathologic findings (such as immune checkpoint inhibitors or olmesartan) and have histomorphologic overlap with many other commonly encountered disease entities. This review discusses the histopathologic features of some relatively recently described drugs causing GI tract injury, namely doxycycline, tacrolimus, mycophenolate, immune checkpoint inhibitors, and olmesartan. We also discuss the common mimics in histopathologic differential and some pearls that can help distinguish GI tract injury induced by the aforementioned drugs from its mimics. Awareness of the wide spectra of histopathologic changes associated with these drugs is crucial for practicing pathologists, to avoid misdiagnosis and guiding the clinician for an optimal patient management, which usually involves modifying or discontinuing the offending drug. Needless to say, once a diagnosis of drug-induced injury is suspected, clinicopathologic correlation including corroboration with the drug history is of utmost importance as is the exclusion of dual pathology in these patients.

Global research trends on precision cancer medicine-related rashes (2008-2021): A bibliographic study

Background

Precision cancer medicine-related rashes are a kind of skin and mucous lesions caused by precision therapy. More and more evidences indicated that such events should not be ignored in the course of anti-tumor therapy. Since cancer treatment entered the “Precision Era”, there has been a rapid increase in this field. However, there was few bibliometric studies to provide an overall review of this field. This study aims to evaluate the literature output and trends in researches on precision cancer medicine-related rashes from a global perspective.

Methods

Collected publications on precision cancer medicine-related rashes from the Web of Science Core Collection database, which were limited to articles and reviews in English. Microsoft Excel, VOS viewer and CiteSpace V were used for quantitative and visual analysis.

Results

A total of 1,229 papers were identified. From 2008 to 2021, annual publications increased year by year. The United States published the most papers in this field (44.9%) and ranking first in citation frequency (19,854 times) and H-index (69). The University of Texas system ranks first with 98 papers published. Lacouture M.E and Robert C were the principal investigators. Cancers has the largest number of articles published, with 70 articles. In recent years, there have been research hotspots related to immunotherapy, including ipilimumab, immunotherapy, tumor microenvironment, association, checkpoint inhibitor, and cutaneous adverse event.

Conclusion

Precision cancer medicine-related rashes are a hot research topic in oncology. The number of relevant publications will increase dramatically. “Checkpoint inhibitors”, “skin adverse events”, “associations” and “tumor microenvironment” may become research hotspots in the future.

Immunotherapy-induced Colitis: A Comprehensive Review of Epidemiology, Clinical Presentation, Diagnostic Workup, and Management Plan

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of a variety of malignancies including advanced melanoma, non-small cell lung cancer, renal cell carcinoma, head and neck cancers among others. Since their introduction, there has been significant improvement in survival and prognosis in patients with advanced malignancies. Unfortunately, improved outcomes have come at a price of significant immune-related adverse events, with those of the gastrointestinal tract being the most common. Gastrointestinal immune-related adverse events frequently present as diarrhea and colitis, the severity of which can range from mild diarrhea to fulminant colitis with intestinal perforation. Currently, management of ICI-induced colitis is primarily guided by retrospective studies and expert opinion. A significant number of ICI-induced colitis responds to high-dose corticosteroids; however, some patients require further therapy with biologics. There is limited information on the factors which may predispose patients to ICI-induced colitis. Future research elucidating these risk factors along with development of a scoring system could allow for risk-stratification of patients before initiation of ICI therapy. Such a system may help clinicians and patients keep a high index of suspicion regarding ICI-induced colitis and could hopefully reduce the incidence of severe cases. Similarly, future studies should investigate protective factors against ICI-induced colitis, which could potentially allow more patients to safely benefit from ICI therapy.

Gastrointestinal and Hepatobiliary Immune-related Adverse Events: A Histopathologic Review

Immune checkpoint inhibitors have been increasingly used to treat various malignant neoplasms. Despite their superior efficacy in treating certain ones, their global immune-activation effect leads to systemic side effects, referred to as immune-related adverse events. Immune-related adverse events affect a variety of organs, including the skin, gastrointestinal, hepatobiliary, and endocrine organs. Gastrointestinal tract immune-related adverse events present with a wide range of symptoms with variable severity, which may lead to treatment interruption and administration of immunosuppression therapy in many cases. Histopathologic changes are diverse, overlapping with many other conditions. Therefore, recognizing these changes is crucial in diagnosing immune-related adverse events. This review discusses the pathologic manifestations of gastrointestinal immune-related adverse events and discusses the primary differential diagnoses.

Gut inflammation induced by drugs: Can pathology help to differentiate from inflammatory bowel disease?

Drug‐induced mucosal injury (DIMI) in the gastrointestinal tract is important to recognise, partly because cessation of the culprit agent alone may result in resolution of symptoms. An ever‐growing list of medications, including newer immunotherapeutic agents and targeted therapies, can cause gastrointestinal inflammation of varying severity. However, the diagnosis of DIMI is challenging, as a single drug can induce a variety of histopathological patterns of injury including acute colitis, chronic colitis, microscopic colitis, apoptotic colopathy, and ischaemic‐type colitis. An additional consideration is the potential clinical, endoscopic and histological overlap of DIMI with gastrointestinal mucosal injury secondary to other entities such as inflammatory bowel disease (IBD). We discuss DIMI of the gastrointestinal tract with an emphasis on histological patterns that mimic IBD, histological features which may distinguish the two entities, and the diagnostic role and limitations of the pathologist.

ECCO Topical Review on Clinicopathological Spectrum and Differential Diagnosis of Inflammatory Bowel Disease

INTRODUCTION

Many diseases can imitate inflammatory bowel disease [IBD] clinically and pathologically. This review outlines the differential diagnosis of IBD and discusses morphological pointers and ancillary techniques that assist with the distinction between IBD and its mimics.

METHODS

European Crohn's and Colitis Organisation [ECCO] Topical Reviews are the result of an expert consensus. For this review, ECCO announced an open call to its members and formed three working groups [WGs] to study clinical aspects, pathological considerations, and the value of ancillary techniques. All WGs performed a systematic literature search.

RESULTS

Each WG produced a draft text and drew up provisional Current Practice Position [CPP] statements that highlighted the most important conclusions. Discussions and a preliminary voting round took place, with subsequent revision of CPP statements and text and a further meeting to agree on final statements.

CONCLUSIONS

Clinicians and pathologists encounter a wide variety of mimics of IBD, including infection, drug-induced disease, vascular disorders, diverticular disease, diversion proctocolitis, radiation damage, and immune disorders. Reliable distinction requires a multidisciplinary approach.

Bridging the Gap: Connecting the Mechanisms of Immune-Related Adverse Events and Autoimmunity Through PD-1

The emergence of anti-cytotoxic T-lymphocyte antigen 4 (anti-CTLA-4), anti-programmed cell death 1 ligand (anti-PD-1), and anti-PD-L1 antibodies as immune checkpoint inhibitors (ICIs) revolutionized the treatment of numerous types of tumors. These antibodies, both alone and in combination, provide great clinical efficacy as evidenced by tumor regression and increased overall patients' survival. However, with this success comes multiple challenges. First, while patients who respond to ICIs have outstanding outcomes, there remains a large proportion of patients who do not respond at all. This all-or-none response has led to looking downstream of programmed cell death 1 (PD-1) for additional therapeutic targets and for new combination therapies. Second, a majority of patients who receive ICIs go on to develop immune-related adverse events (irAEs) characterized by end-organ inflammation with T-cell infiltrates. The hallmarks of these clinically observed irAEs share many similarities with primary autoimmune diseases. The contribution of PD-1 to peripheral tolerance is a major mechanism for protection against expansion of self-reactive T-cell clones and autoimmune disease. In this review, we aim to bridge the gaps between our cellular and molecular knowledge of PD-1 signaling in T cells, ICI-induced irAEs, and autoimmune diseases. We will highlight shared mechanisms and the potential for new therapeutic strategies.

Immune Checkpoint Inhibitor-Associated Colitis: From Mechanism to Management

Immune checkpoint inhibitors (ICIs), as one of the innovative types of immunotherapies, including programmed cell death-1 (PD-1), programmed cell death-ligand 1 (PD-L1), and cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors, have obtained unprecedented benefit in multiple malignancies. However, the immune response activation in the body organs could arise immune-related adverse events (irAEs). Checkpoint inhibitor colitis (CIC) is the most widely reported irAEs. However, some obscure problems, such as the mechanism concerning gut microbiota, the confusing differential diagnosis with inflammatory bowel disease (IBD), the optimal steroid schedule, the reintroduction of ICIs, and the controversial prognosis features, influence the deep understanding and precise diagnosis and management of CIC. Herein, we based on these problems and comprehensively summarized the relevant studies of CIC in patients with NSCLC, further discussing the future research direction of this specific pattern of irAEs.

Immune checkpoint inhibitor treatment induces colitis with heavy infiltration of CD8 + T cells and an infiltration pattern that resembles ulcerative colitis

Colitis is a common, but poorly understood, adverse event of immune checkpoint inhibitors that are standard-of-care for an expanding range of cancer types. This explorative study aimed to describe the immune infiltrates in the colon from individuals developing checkpoint inhibitor colitis and compare them to well-known immunophenotypes of acute graft-versus-host disease, ulcerative colitis, and Crohn’s disease. Colon biopsies (n = 20 per group) of patients with checkpoint inhibitor colitis, acute graft-versus-host disease, ulcerative colitis and Crohn’s disease, all colitis treatment-naïve, and of individuals with a normal colon were analyzed using immunohistochemistry: CD8 for cytotoxic T cells, CD4 for T helper cells, and CD68 to identify cells of macrophage lineage. CD8 + T cell, CD4 + T cell, and CD68 + cell counts were performed. Cell infiltration was scored as scattered/patchy or band-like in the superficial and deep gut mucosa. Checkpoint inhibitor colitis was found to be heavily infiltrated by CD8 + T cells. Comparative analysis between groups showed that both CD8 + T cell counts (P < 0.01) and immune cell infiltration patterns in checkpoint inhibitor colitis were most similar to those observed in ulcerative colitis, with a deep band-like CD4 + T cell infiltration pattern and a superficial band-like CD68 + cell infiltration pattern in both. In conclusion, this is the first immunohistopathological study comparing infiltrate characteristics of checkpoint inhibitor colitis, acute graft-versus-host disease, ulcerative colitis, and Crohn’s disease. Checkpoint inhibitor colitis samples are heterogeneous, heavily infiltrated by CD8 + T cells, and show an immune cell infiltration pattern that is more similar to ulcerative colitis than to colonic acute graft-versus-host disease or colonic Crohn’s disease.

Checkpoint Inhibitor Colitis Shows Drug-Specific Differences in Immune Cell Reaction That Overlap With Inflammatory Bowel Disease and Predict Response to Colitis Therapy

OBJECTIVES

Checkpoint inhibitor (CPI)-associated colitis can limit therapy and has resemblance to inflammatory bowel disease (IBD). Studies exploring mechanistic similarities between these colitides are limited, yet therapeutic targets for either disorder could emerge from shared pathophysiology.

METHODS

The morphology and inflammatory content of colonic biopsy specimens from anti-CTLA-4 and anti-PD-1/PD-L1 antibody-treated patients with CPI colitis were compared with initial biopsy specimens from patients with IBD. Predictors of the need for infliximab were sought in CPI patients.

RESULTS

Biopsy specimens from CPI patients showed significantly lower chronicity scores and similar activity scores compared with patients with IBD. Anti-CTLA-4 and IBD groups showed equivalent CD8, CD4, PD-1, and PD-L1 expression, while FoxP3 scores were lower and CD68 scores were higher in anti-CTLA-4 compared with IBD biopsy specimens. Anti-PD-1/PD-L1 group had lower scores for CD8, CD4, and PD-1 and equivalent scores for FoxP3, PD-L1, and CD68 compared with IBD. Anti-CTLA-4 biopsy specimens had higher scores for CD8, PD-1, PD-L1, and CD68 than anti-PD-1/PD-L1 biopsy specimens. CD8/FoxP3 ratios and CD68 scores were higher among CPI patients requiring infliximab therapy for colitis compared with those responding to steroids.

CONCLUSIONS

The proinflammatory immune phenotype of anti-CTLA-4-associated colitis has significant overlap with IBD. CD8/FoxP3 ratios may predict therapeutic response in CPI-associated colitis.

Distribution of mucosal PD-1 expressing T cells in patients with colitis of different etiologies

BACKGROUND

Immunotherapy, targeting programmed death-1 (PD-1) enhances antitumor T-cell activity in patients with malignancies. Blocking PD-1 or its ligand may lead to fulminant colitis as serious adverse event in these patients. Since little is known of the presence and role of PD-1⁺T cells in colitis of different etiologies, we determined PD-1⁺T cells in mucosal specimens of patients with inflammatory bowel disease, infectious colitis (InfC), immunotherapy-related colitis (ImC) and healthy controls (HC).

METHODS

Newly diagnosed patients with ulcerative colitis (UC, n = 73), Crohn's disease (CD, n = 50), InfC (n = 5), ImC (n = 8) and HC (n = 8) were included. Baseline inflamed colonic biopsies were studied with immunohistochemistry and flowcytometry.

RESULTS

Using immunohistochemistry, PD-1 was not present on lymphocytes in the epithelium of all patients, nor in HC. The percentage PD-1⁺ of all lymphocytes in the lamina propria was 40% in UC, 5% in InfC, 3% in ImC and 0% in HC. Flowcytometry showed significant higher percentages of PD-1⁺T cells in inflamed biopsy specimens of UC patients (22%) compared to all other groups: CD patients (13%), InfC (12%), ImC (5%) and HC (6%).

CONCLUSION

There are relevant differences in distribution and frequencies of mucosal PD-1⁺ T-cell subsets in patients with UC, CD, InfC and ImC, supporting the hypothesis that these types of colitis are driven by different immunological pathways. The increased numbers of PD-1⁺ and PD-L1⁺ lymphocytes in the colonic mucosa of UC patients suggest that the PD-1/PD-L1 pathway might be more activated in UC than in CD.

Checkpoint Inhibitor-Induced Colitis-A Clinical Overview of Incidence, Prognostic Implications and Extension of Current Treatment Options

In recent years, anti-tumor immunotherapies have witnessed a major breakthrough with the emergence of immune checkpoint inhibitors (ICIs). However, the use of ICIs has also brought an era of a certain class of adverse events that differ from those of classical chemotherapies and are more reminiscent of autoimmune diseases. This article focuses exclusively on colitis as an irAE with emphasis on vulnerable patient groups, the prognostic significance of colitis, treatment, and new therapeutic approaches that may be applicable. Colitis itself is associated with a favorable oncological outcome of the underlying disease but is as well the most common irAE leading to discontinuation of therapy. Especially in vulnerable patient groups such as IBD patients and elderly patients, colitis occurs more frequently as a side effect. It is precisely in these two patient groups that side effects more often lead to discontinuation of therapy. Therefore, in addition to the current therapy of colitis through immunosuppression, the focus should also be on new forms of therapy of severe colitis, such as fecal transplantation or ileostomy creation.

Ulcerative colitis exacerbation after the onset of immune checkpoint inhibitor related colitis

Immune checkpoint inhibitors (ICPI) have been reported to be effective in various carcinomas. They excessively activate the immune system, resulting in frequent immune-related adverse events (irAEs). Colitis induced by ICPI is one of the most common and is known as immune-mediated colitis (IMC). Although IMC and inflammatory bowel disease (IBD) are similar in many respects, there are very few reports of IMC in patients with preexisting IBD such as ulcerative colitis (UC) and Crohn's disease (CD). Whether preexisting IBD is concerned with the development of the colitis is not well known. Here, we reported the case who developed severe ulcerative colitis which started from IMC. It is an important case to follow the time course of the colitis developed. Our conclusion indicated that frequent colonoscopy was important for the management of IMC in a patient who has suffered chronic inflammatory disease, such as UC.

A case of autoimmune enteropathy with CTLA4 haploinsufficiency

Autoimmune enteropathy (AIE) is a rare disease, characterized by intractable diarrhea, villous atrophy of the small intestine, and the presence of circulating anti-enterocyte autoantibodies. Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, and mutations in FOXP3, which is a master gene of regulatory T cells (Tregs), are major causes of AIE. Recent studies have demonstrated that mutations in other Treg-associated genes, such as CD25 and CTLA4, show an IPEX-like phenotype. We present the case of a 13-year-old girl with CTLA4 haploinsufficiency, suffering from recurrent immune thrombocytopenic purpura and intractable diarrhea. We detected an autoantibody to the AIE-related 75 kDa antigen (AIE-75), a hallmark of the IPEX syndrome, in her serum. She responded well to a medium dose of prednisolone and a controlled dose of 6-mercaptopurine (6-MP), even after the cessation of prednisolone administration. Serum levels of the soluble interleukin-2 receptor and immunoglobulin G (IgG) were useful in monitoring disease activity during 6-MP therapy. In conclusion, autoimmune-mediated mechanisms, similar to the IPEX syndrome, may be involved in the development of enteropathy in CTLA4 haploinsufficiency. Treatment with 6-MP and monitoring of disease activity using serum levels of soluble interleukin-2 receptor and IgG is suggested for such cases.

Programmed cell death-1 (PD-1) and programmed death-ligand 1 (PD-L1) expression in PD-1 inhibitor-associated colitis and its mimics

AIMS

Immune checkpoint inhibitors (ICIs) have revolutionised the treatment of advanced malignancies by boosting immune-mediated destruction of neoplastic cells, but are associated with side effects stemming from generalised immune system activation against normal tissues. Checkpoint ligand expression in non-tumoral cells of tissues affected by immune-related adverse effects has been described in ICI-associated hypophysitis, myocarditis, and acute interstitial nephritis. We aimed to investigate the tissue expression of the immune checkpoint receptor programmed cell death-1 (PD-1) and its ligand, programmed death-ligand 1 (PD-L1), in PD-1 inhibitor-associated colitis (PD1i colitis).

METHODS AND RESULTS

PD-1 and PD-L1 immunohistochemical expression levels were analysed in 15 cases of PD1i colitis and potential mimics-infectious colitis and inflammatory bowel disease (IBD). Increased epithelial expression of PD-L1 was observed in PD1i colitis as compared with normal colon and infectious colitis, but the expression level was lower than that in IBD. Conversely, PD-1 expression in inflammatory cells was higher in infectious colitis, intermediate in IBD, and minimal or absent in normal colon and in patients receiving PD-1 inhibitors.

CONCLUSIONS

Although our results do not justify the use of PD-L1 as a discriminatory marker of PD1i colitis against other entities within the differential diagnosis, they support the concept that PD1i colitis and IBD have similar pathogenetic mechanisms. They also highlight the fact that PD-L1 epithelial overexpression is a commonly used mechanism of the gastrointestinal tract mucosa to protect itself from inflammatory-mediated damage resulting from different aetiologies, which probably underpins the high incidence of gastrointestinal immune-related adverse effects in patients receiving ICI therapies, in whom this mechanism is disrupted.

Management of Patients With Immune Checkpoint Inhibitor-Induced Enterocolitis: A Systematic Review

Immune checkpoint inhibitors (ICIs) have improved the treatment of several cancers. These drugs increase T-cell activity and the antitumor immune response but also have immune-related adverse effects that can affect the gastrointestinal (GI) tract. These adverse effects have been observed in 7% to 30% of patients treated with ICIs. As the number of diseases treated with ICIs increases, gastroenterologists will see more patients with ICI-induced GI adverse events. We performed a systematic review of the incidence, risk factors, clinical manifestations, and management of the adverse effects of ICIs on the GI tract. Treatment with anti-cytotoxic T-lymphocyte-associated antigen-4 often causes severe enterocolitis, whereas treatment with inhibitors of programmed cell death 1 have less frequent and more diverse adverse effects. Management of patients with GI adverse effects of ICIs should involve first ruling out other disorders, followed by assessment of severity, treatment with corticosteroids, and rapid introduction of infliximab therapy for nonresponders.

Autoimmune complications of immunotherapy: pathophysiology and management

Immune checkpoint inhibitors (ICIs) are monoclonal antibodies that target inhibitory molecules, such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), programmed cell death protein 1 (PD-1), or its ligand, programmed cell death protein ligand 1 (PD-L1), and lead to immune activation in the tumor micro-environment. ICIs can induce durable treatment responses in patients with advanced cancers, but they are commonly associated with immune related adverse events (irAEs) such as rash, colitis, hepatitis, pneumonitis, and endocrine and musculoskeletal disorders. Almost all patients experience some form of irAE, but high grade irAEs occur in approximately half of those on combination therapy (eg, anti-CTLA-4 plus anti-PD-1), and up to one quarter receiving ICI monotherapy. Fatal irAEs occur in approximately 1.2% of patients on CTLA-4 blockade and 0.4% of patients receiving PD-1 or PD-L1 blockade, and case fatality rates are highest for myocarditis and myositis. IrAEs typically occur in the first three months after ICI initiation, but can occur as early as one day after the first dose to years after ICI initiation. The mainstay of treatment is with corticosteroids, but tumor necrosis factor inhibitors are commonly used for refractory irAEs. Although ICIs are generally discontinued when high grade irAEs occur, ICI discontinuation alone is rarely adequate to resolve irAEs. Consensus guidelines have been published to help guide management, but will likely be modified as our understanding of irAEs grows.

Human leucocyte antigen DR15, a possible predictive marker for immune checkpoint inhibitor-induced secondary adrenal insufficiency

BACKGROUND

Immune checkpoint inhibitors (ICPis) induce various immune-related adverse events (irAEs), despite their beneficial effects in treating various advanced cancers. ICPi-induced secondary adrenal insufficiency is described as a prevalent and serious 'pituitary irAE.' However, its precise mechanism remains unclear, and no definitive predictive markers have been reported.

PATIENTS AND METHODS

We enrolled and studied 11 patients with advanced cancer (aged 39-70 years; 6 male patients) receiving nivolumab, pembrolizumab or ipilimumab who developed pituitary irAEs. Their clinical data, including endocrine functions, were retrospectively assessed and human leucocyte antigen (HLA) genotypes were determined to compare the HLA allele frequencies in these patients and healthy controls.

RESULTS

Among 11 patients, 7, 3 and 1 patients exhibited malignant melanoma, non-small-cell lung cancer and gastric cancer, respectively. HLA type screening results revealed that HLA-DR15, B52 and Cw12 were observed in 9, 7, and 7 patients with pituitary irAE, respectively. DR15, B52 and Cw12 were significantly more prevalent in our group than in the healthy control group from the Japanese HLA-haplotype database (this study vs healthy control group); DR15: 81.8% vs 33.5% (n = 11, P = 0.0014), B52: 63.6% vs 21.0% (n = 11, P = 0.0026) and Cw12: 70% vs 21.3% (n = 10, P = 0.0013).

CONCLUSIONS

HLA-DR15, B52 and Cw12 are possible predisposing factors for pituitary irAEs. HLA-DR15 is reportedly associated with autoimmune disease via interleukin-17 regulation, suggesting its involvement in pituitary irAE development. Using HLA haplotypes as pituitary irAE predictive markers, we could provide safe ICPi treatment and understand irAE pathogenesis.

Pathology of immune-mediated tissue lesions following treatment with immune checkpoint inhibitors

Immune check point inhibitor (CPI) therapy has revolutionized treatment paradigms for several cancers, but at the cost of triggering a diverse spectrum of immune-mediated injury to non-cancer tissues. The complex biology of these toxicities remains incompletely understood, partly because tissue acquisition from affected areas can be challenging to retrieve, thus hindering development of targeted therapy. Here, we review the literature describing pathology of immune-mediated tissue lesions including gastrointestinal, skin, rheumatic, pulmonary, cardiac, renal and hepatic lesions and highlight key immunological insights.

18th Annual Meeting of the Safety Pharmacology Society: drug safety assessment on gastrointestinal system functions

Introduction: The 18^th Annual Meeting of the Safety Pharmacology Society included a session dedicated to the assessment of drug safety on the gastrointestinal (GI) system.Areas covered: GI anatomy, physiology, adverse effects (AEs) of chemical and biological therapies, and approaches to mitigate them.Expert opinion: GI AEs, albeit common and generally of minor intensity, may prolong clinical development time and reduce patient compliance.

A Computational Model of Neoadjuvant PD-1 Inhibition in Non-Small Cell Lung Cancer

Immunotherapy and immune checkpoint blocking antibodies such as anti-PD-1 are approved and significantly improve the survival of advanced non-small cell lung cancer (NSCLC) patients, but there has been little success in identifying biomarkers capable of separating the responders from non-responders before the onset of the therapy. In this study, we developed a quantitative system pharmacology (QSP) model to represent the anti-tumor immune response in human NSCLC that integrated our knowledge of tumor growth, antigen processing and presentation, T cell activation and distribution, antibody pharmacokinetics, and immune checkpoint dynamics. The model was calibrated with the available data and was used to identify potential biomarkers as well as patient-specific response based on the patient parameters. The model predicted that in addition to tumor mutational burden (TMB), a known biomarker for anti-PD-1 therapy in NSCLC, the number of effector T cells and regulatory T cells in the tumor and blood is a predictor of the responders. Furthermore, the model simulated a set of 12 patients with known TMB and MHC/antigen-binding affinity from a recent clinical trial (ClinicalTrials.gov number, NCT02259621) on neoadjuvant nivolumab therapy in resectable lung cancer and predicted an augmented durable response in patients with adjuvant nivolumab treatment in addition to the clinical trial protocol of neoadjuvant nivolumab treatment followed by resection. Overall, the model provides a valuable framework to model tumor immunity and response to immune checkpoint blockers to enhance biomarker discovery and performing virtual clinical trials to aid in design and interpretation of the current trials with fewer patients.

Nivolumab-induced immune-mediated colitis: an ulcerative colitis look-alike-report of new cases and review of the literature

PURPOSE

Nivolumab, a monoclonal antibody-targeting programmed cell death protein-1, is being increasingly used for the treatment of some advanced neoplasms. Several of its adverse effects are a result of the upregulation of T cells, with colitis as one of the most severe, and a challenging differential diagnosis with ulcerative colitis. However, few real-life clinical practice cases have been reported beyond trials. Our aim was to report a series of new cases, reviewing previously communicated endoscopic-proven nivolumab-induced colitis.

METHOD

All patients treated with nivolumab in three university centers were identified and those who developed immune-mediated colitis (defined as the presence of diarrhea and evidence of colitis demonstrated by colonoscopy) were described. Additionally, a review of case reports of nivolumab-induced colitis reported in the literature up to March 2018 was performed.

RESULTS

Six new cases of nivolumab-induced colitis and 13 previously reported cases out of randomized clinical trials are described. Colonoscopy showed a mucosal pattern mimicking ulcerative colitis in a large proportion of patients. Clostridium difficile superinfection was observed in two out of 19 cases. All but three patients definitively discontinued nivolumab therapy. Most patients were initially managed with oral or intravenous corticosteroids, but five of them required rescue therapy with infliximab.

CONCLUSIONS

Nivolumab-induced colitis may mimic ulcerative colitis. Steroid therapy (oral or intravenously) is often efficient, but one-fourth of patients need rescue therapy with anti-TNF. Intestinal superinfection with Clostridium difficile or cytomegalovirus should be ruled out before starting immunosuppressive therapy.

Checkpoint inhibitor-associated autoimmunity

Checkpoint inhibitors (CI) have revolutionized the management of many cancers but can result in immune-related adverse events (IRAE). In this chapter, we review the clinical manifestations and management of the most common IRAE, plus less common IRAE, such as inflammatory arthritis, of particular interest to rheumatologists. We review the mechanism of action of CI, predictors of IRAE, and the impact of IRAE on cancer outcomes. The study of IRAE is in its infancy; there are very few prospective studies and virtually no treatment trials. Where possible, we have drawn estimates of IRAE incidence from meta-analyses of randomized controlled trials. Clinical descriptions are derived from case series and case reports. Readers are encouraged to refer to consensus guidelines for IRAE management published by the American Society of Clinical Oncology and the Society for Immunotherapy of Cancer.

Checkpoint inhibitor colitis: a new model of inflammatory bowel disease?

PURPOSE OF REVIEW

Immune checkpoint inhibitors are monoclonal antibodies against the inhibitory, co-stimulatory molecules CTLA-4 and PD-1/PD-L1. Their use in oncology has been associated with frequent and diverse immune-related adverse events. In the digestive tract, such toxicity presents primarily as colonic inflammation, resembling inflammatory bowel disease (IBD). This review presents recent developments regarding the characteristics of checkpoint inhibitor colitis (CIC) and its relation to IBD.

RECENT FINDINGS

Several reports from patient cohorts with CIC have outlined its similarities and differences with IBD. Clinically and endoscopically, there is high overlap, including the negative prognostic significance of deep ulceration. Histologically, CIC may present as either acute colitis or demonstrate features of chronic damage, including IBD-like and lymphocytic colitis-like phenotypes. CIC immunopathogenesis appears to be associated with a predominance of mucosal Th1/Th17 effector responses, and may also be influenced by input from the gut microflora. Finally, current treatment of CIC is based on steroids and infliximab, although other biologics such as vedolizumab may also be effective.

SUMMARY

CIC represents a distinct form of colitis with characteristics reminiscent of IBD flares. Clarification of the mechanisms involved in its pathogenesis will greatly enhance our understanding and therapeutic management of immune-mediated colitides, including IBD.