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

Review of T Helper 2-Type Inflammatory Diseases Following Immune Checkpoint Inhibitor Treatment

Immune checkpoints are mechanisms that allow cancer cells to evade immune surveillance and avoid destruction by the body's immune system. Tumor cells exploit immune checkpoint proteins to inhibit T cell activation, thus enhancing their resistance to immune attacks. Immune checkpoint inhibitors, like nivolumab, work by reactivating these suppressed T cells to target cancer cells. However, this reactivation can disrupt immune balance and cause immune-related adverse events. This report presents a rare case of prurigo nodularis that developed six months after administering nivolumab for lung adenocarcinoma. While immune-related adverse events are commonly linked to T helper-1- or T helper-17-type inflammations, T helper-2-type inflammatory reactions, as observed in our case, are unusual. The PD-1-PD-L1 pathway is typically associated with T helper-1 and 17 responses, whereas the PD-1-PD-L2 pathway is linked to T helper-2 responses. Inhibition of PD-1 can enhance PD-L1 functions, potentially shifting the immune response towards T helper-1 and 17 types, but it may also influence T helper-2-type inflammation. This study reviews T helper-2-type inflammatory diseases emerging from immune checkpoint inhibitor treatment, highlighting the novelty of our findings.

Cardiovascular toxicities of immune therapies for cancer - a scientific statement of the Heart Failure Association (HFA) of the ESC and the ESC Council of Cardio-Oncology

The advent of immunological therapies has revolutionized the treatment of solid and haematological cancers over the last decade. Licensed therapies which activate the immune system to target cancer cells can be broadly divided into two classes. The first class are antibodies that inhibit immune checkpoint signalling, known as immune checkpoint inhibitors (ICIs). The second class are cell-based immune therapies including chimeric antigen receptor T lymphocyte (CAR-T) cell therapies, natural killer (NK) cell therapies, and tumour infiltrating lymphocyte (TIL) therapies. The clinical efficacy of all these treatments generally outweighs the risks, but there is a high rate of immune-related adverse events (irAEs), which are often unpredictable in timing with clinical sequalae ranging from mild (e.g. rash) to severe or even fatal (e.g. myocarditis, cytokine release syndrome) and reversible to permanent (e.g. endocrinopathies).The mechanisms underpinning irAE pathology vary across different irAE complications and syndromes, reflecting the broad clinical phenotypes observed and the variability of different individual immune responses, and are poorly understood overall. Immune-related cardiovascular toxicities have emerged, and our understanding has evolved from focussing initially on rare but fatal ICI-related myocarditis with cardiogenic shock to more common complications including less severe ICI-related myocarditis, pericarditis, arrhythmias, including conduction system disease and heart block, non-inflammatory heart failure, takotsubo syndrome and coronary artery disease. In this scientific statement on the cardiovascular toxicities of immune therapies for cancer, we summarize the pathophysiology, epidemiology, diagnosis, and management of ICI, CAR-T, NK, and TIL therapies. We also highlight gaps in the literature and where future research should focus.

Acute kidney injury associated with anti-PD-1 and anti-PD-L1 drugs: a meta-analysis of randomized clinical trials

BACKGROUND

Immune Checkpoint Inhibitors (ICI) have been widely used in treating different types of cancer. They increase survival in many oncologic patients and enable cancer-specific therapy. Acute Kidney Injury (AKI) is one of the adverse effects associated with using ICI, where knowledge of the prevalence and renal histological findings are still reasons for discussion.

OBJECTIVE

Therefore, this meta-analysis evaluates the association between ICI use and AKI.

METHODS

The search was performed in PubMed, Lilacs, and Cochrane platforms. Studies published up to December 1, 2022, were included.

RESULTS

A total of 16 studies met the established PICOT criteria and were included in this review. Comparing the ICI plus chemotherapy against chemotherapy alone, the relative risk (RR) for AKI's development with ICI use was 2.89 (95%CI 1.37-6.10). In the analyses by class and drug type, programmed cell death 1 monoclonal antibody (anti-PD-1) showed an increased risk of 2.11 (95%CI 1.26-3.52), and pembrolizumab demonstrated a risk of AKI (RR= 2.77, 95%CI 1.46-5.26). Likewise, regarding the severity of AKI, AKI grade 3 or higher was more common in the ICI plus chemotherapy compared to the chemotherapy group: 3.66 (95%CI 1.19-11.30), while the subgroup analyses pooled studies comparing ICI alone versus chemotherapy alone in the control group did not demonstrate an association with AKI.

CONCLUSIONS

These findings suggest that ICI use is associated with an increased risk of AKI and that anti-PD-1 use is associated with a higher incidence of renal adverse events than programmed cell death ligand 1 monoclonal antibody (anti-PD-L1). Studies with adequate power and well-defined criteria for acute interstitial nephritis, nowadays taken as a synonym for AKI related to ICI, are necessary.

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.

Distinct patterns of auto-reactive antibodies associated with organ-specific immune-related adverse events

The roles of preexisting auto-reactive antibodies in immune-related adverse events (irAEs) associated with immune checkpoint inhibitor therapy are not well defined. Here, we analyzed plasma samples longitudinally collected at predefined time points and at the time of irAEs from 58 patients with immunotherapy naïve metastatic non-small cell lung cancer treated on clinical protocol with ipilimumab and nivolumab. We used a proteomic microarray system capable of assaying antibody reactivity for IgG and IgM fractions against 120 antigens for systemically evaluating the correlations between auto-reactive antibodies and certain organ-specific irAEs. We found that distinct patterns of auto-reactive antibodies at baseline were associated with the subsequent development of organ-specific irAEs. Notably, ACHRG IgM was associated with pneumonitis, anti-cytokeratin 19 IgM with dermatitis, and anti-thyroglobulin IgG with hepatitis. These antibodies merit further investigation as potential biomarkers for identifying high-risk populations for irAEs and/or monitoring irAEs during immunotherapy treatment.

Trial registration

ClinicalTrials.gov identifier: NCT03391869.

Pathogenesis, pathological characteristics and individualized therapy for immune-related adverse effects

Immune checkpoint inhibitors (ICIs) are a class of antitumor medications that target immune checkpoints, which induce the activation of lymphocytes. These treatments effectively prolong the survival of patients with advanced tumors, especially lung cancer. However, in addition to tumor killing effects, ICIs may also cause an imbalance between immune tolerance and immunity. Over-activated lymphocytes may cause various types of damage to multiple organs throughout the body, called immune-related adverse events. In this review, we summarize the pathogenesis, pathological characteristics, biomarkers, and therapeutic agents for immune-related adverse events.

Immune checkpoint inhibitor-induced cutaneous toxicities: a review of histopathologic and clinical features

Immune checkpoint inhibitors (ICIs) represent an emerging treatment option for a variety of cancer types. Through inhibition of programmed cell death protein 1 (PD-1), programmed cell death ligand 1 (PD-L1), and/or cytotoxic lymphocyte-associated antigen-4 (CTLA-4), ICIs activate the host's immune system causing a heightened anti-tumor response. However, off-target effects of ICIs can result in numerous different immune-related cutaneous adverse events (irCAEs). Beyond impacting quality of life, irCAEs can lead to dose limitations or discontinuation of anti-cancer therapies. Correct diagnosis is necessary for expedient and appropriate management. Skin biopsies are often performed to increase diagnostic accuracy and guide clinical management. An extensive literature review was performed using the PubMed database to identify the reported clinical and histopathologic features of irCAEs. This comprehensive review primarily details the histopathologic features of various irCAEs reported to date. Clinical presentation and immunopathogenesis are also discussed in relation to histopathology.

Collagenous Colitis in a Patient With Gastric Cancer Who Underwent Chemotherapy

Herein, we present a case of collagenous colitis in a patient who underwent chemotherapy for gastric cancer, comprising five cycles of S-1 plus oxaliplatin and trastuzumab, followed by five cycles of paclitaxel and ramucirumab and seven cycles of nivolumab. The subsequent initiation of trastuzumab deruxtecan chemotherapy led to the development of grade 3 diarrhea after the second cycle of treatment. Collagenous colitis was diagnosed via colonoscopy and biopsy. The patient's diarrhea improved following the cessation of lansoprazole. This case highlights the importance of considering collagenous colitis as a differential diagnosis, in addition to chemotherapy-induced colitis and immune-related adverse event (irAE) colitis, in patients with similar clinical presentations.

Immediate hypersensitivity reactions to antineoplastic agents - A practical guide for the oncologist

Immediate hypersensitivity reactions (IHRs) to antineoplastic agents occur frequently, and every oncologist will encounter these reactions in their clinical practice at some point. The clinical signature of IHRs can range from mild to life-threatening, and their occurrence can substantially impede the treatment course of patients with cancer. Yet, clear guidelines regarding the diagnosis and management are scarce, especially from an oncologic point of view. Therefore, herein, we review the definition, pathophysiology, epidemiology, diagnosis and management of IHRs to chemotherapeutic agents and monoclonal antibodies. First, we focus on defining the specific entities that comprise IHRs and discuss their underlying mechanisms. Then, we summarize the epidemiology for the antineoplastic agents that represent the most common causes of IHRs, i.e., platinum compounds, taxanes and monoclonal antibodies (mAbs). Next, we describe the possible clinical pictures and the comprehensive diagnostic work-up that should be executed to identify the culprit and safe alternatives for the future. Finally, we finish with reviewing the treatment options in both the acute phase and after recovery, with the aim to improve the oncologic care of patients with cancer.

Outcomes of immunotherapy-related hepatotoxicity from a multi-disciplinary toxicity team

BACKGROUND

Despite the efficacy of immune checkpoint inhibitors (ICIs), adverse events including hepatotoxicity limit their ongoing use. We investigated the outcomes and management of patients with immune-mediated hepatitis (IMH) and clinical predictors of toxicity resolution.

METHODS

Patients referred to our multidisciplinary immunotherapy-related toxicity group from August 2017 to December 2020 for IMH were evaluated. Toxicity was defined according to CTCAEv4.0. IMH resolution was defined as liver enzyme normalization after steroid initiation.

RESULTS

Thirty-three patients were included in the study, 62% female, and 71% Caucasian. The most common ICI used was PD-1/PD-L1 (76%). Peak IMH occurred at a median of 89 [45,193] days, for which most patients received 1-2 mg/kg/day prednisone equivalent with 35% requiring MMF. Median follow-up was 123 [33,472] days with IMH resolution seen in 48% of patients at a median of 111 [41,214] days. While high-dose steroid use was not associated with IMH resolution, liver enzyme improvement one week after steroids predicted resolution in univariate analysis (p = 0.041). All 11 patients without IMH resolution died from cancer progression or complications with three patients having acute liver failure. Available liver biopsies showed bile duct injury, with varying degrees of portal and lobular inflammation.

CONCLUSION

IMH improvement one week after steroid initiation may predict ultimate IMH resolution.

Utilizing Biologics in Drug Desensitization

PURPOSE OF REVIEW

The purpose of this literature review was to review the latest advancements with biologics in rapid drug desensitization. Our methodology was to highlight both desensitization to biologics themselves and the use of biologics in desensitization to both biologic and nonbiologic drugs.

RECENT FINDINGS

Biologics are a vast category of drugs that include monoclonal antibodies, nanobodies, modern vaccinations, and even hormones. Desensitization to biologics can be safely performed through standardized procedure. Biomarkers are used both in vitro and in vivo to help identify and classify hypersensitivity reactions. Hypersensitivity reactions to the mRNA vaccinations against SARS-CoV-2 present their own unique challenges to management. There are specific excipients in monoclonal antibodies that are thought to be responsible for many of their hypersensitivity reactions. Certain biologics can even be used to assist in desensitization to other drugs. Rapid drug desensitization is a standardized procedure that may be able to help many patients who have experienced hypersensitivity reactions to biologics and would best be treated with them to continue to receive them. Biologic drugs have opened a new era in medicine for the prevention and treatment of infectious diseases, cancer, and inflammatory diseases. Hypersensitivity reactions to biologics are quite common. This literature review presents the latest advancements in our understanding of hypersensitivity reactions to biologics, how rapid drug desensitization can be used to continue therapy despite history of hypersensitivity, and how biologics themselves can be used to aid in desensitization itself.

Immune-related pulmonary toxicities of checkpoint inhibitors in non-small cell lung cancer: Diagnosis, mechanism, and treatment strategies

Immune checkpoint inhibitors (ICI) therapy based on programmed cell death-1 (PD-1) and programmed cell death ligand 1 (PD-L1) has changed the treatment paradigm of advanced non-small cell lung cancer (NSCLC) and improved the survival expectancy of patients. However, it also leads to immune-related adverse events (iRAEs), which result in multiple organ damage. Among them, the most common one with the highest mortality in NSCLC patients treated with ICI is checkpoint inhibitor pneumonitis (CIP). The respiratory signs of CIP are highly coincident and overlap with those in primary lung cancer, which causes difficulties in detecting, diagnosing, managing, and treating. In clinical management, patients with serious CIP should receive immunosuppressive treatment and even discontinue immunotherapy, which impairs the clinical benefits of ICIs and potentially results in tumor recrudesce. Therefore, accurate diagnosis, detailedly dissecting the pathogenesis, and developing reasonable treatment strategies for CIP are essential to prolong patient survival and expand the application of ICI. Herein, we first summarized the diagnosis strategies of CIP in NSCLC, including the classical radiology examination and the rising serological test, pathology test, and artificial intelligence aids. Then, we dissected the potential pathogenic mechanisms of CIP, including disordered T cell subsets, the increase of autoantibodies, cross-antigens reactivity, and the potential role of other immune cells. Moreover, we explored therapeutic approaches beyond first-line steroid therapy and future direction based on targeted signaling pathways. Finally, we discussed the current impediments, future trends, and challenges in fighting ICI-related pneumonitis.

Multiple White Plaques in the Esophagus: A Possible Case of Esophageal Mucosal Alteration Associated With Immune-Related Adverse Events of Immune Checkpoint Inhibitors

We report two cases of multiple white plaques in the esophagus that emerged after the administration of immune checkpoint inhibitors. Both patients developed enterocolitis as immune-related adverse events associated with immune checkpoint inhibitors. Esophagogastroduodenoscopy revealed duodenal involvement and multiple white plaques in the esophagus. A biopsy of the esophagus showed predominant CD3⁺ lymphocyte infiltration, suggesting that esophageal mucosal alterations were associated with immune-related adverse events. In addition, histopathology showed keratinized stratified squamous epithelium in the first case while increased inflammatory cell infiltration in the intraepithelial and subepithelial layers was observed in the second case. These data suggest a different pathogenesis of the multiple esophageal white plaques between the two cases. Although further investigation is needed to elucidate the significance of these observations, recognition of the esophageal plaques may be important for prompt diagnosis of immune-related adverse events when associated with immune checkpoint inhibitors.

Immune checkpoint inhibitor (ICI)-induced hepatitis diagnosed by liver biopsy followed by ICI-free chemotherapy leading to therapeutic effect: A case of lung cancer treatment

In recent years, the combination of platinum-based chemotherapy and immune checkpoint inhibitors (ICIs) has become the standard treatment for patients with lung cancer. Hepatitis is one of the common toxicities following ICI/chemotherapy. When drug-induced hepatitis occurs, the suspected drug must be discontinued. Since it may be difficult to determine the exact drug causing the hepatitis, liver biopsy may help identify this. We report the case of a patient diagnosed with immune-related adverse event hepatitis from liver biopsy and clinical course.

A 45-year-old man with lung adenocarcinoma (stage IV, cT4N3M1c) negative for driver gene mutation was treated with carboplatin (CBDCA), pemetrexed (PEM), and pembrolizumab. Elevated blood aspartate aminotransferase and alanine aminotransferase levels after chemotherapy indicated hepatitis induced by cytotoxic anticancer agents and ICIs. As autoimmune hepatitis was also suspected, liver biopsy was performed and the findings suggested ICI-induced hepatitis. Pembrolizumab was discontinued and CBDCA/PEM was resumed, following which, the primary lesion shrank. When drug-induced hepatitis is suspected, clinicians should actively perform liver biopsy to confirm the diagnosis, so that appropriate therapeutic regimen can be administered.

Urinary T cells are detected in patients with immune checkpoint inhibitor-associated immune nephritis that are clonotypically identical to kidney T cell infiltrates

Acute kidney injury (AKI) occurs in ~20% of patients receiving immune checkpoint inhibitor (ICI) therapy; however, only 2-5% will develop ICI-mediated immune nephritis. Conventional tests are nonspecific in diagnosing disease pathology and invasive procedures (i.e. kidney biopsy) may not be feasible. In other autoimmune renal diseases, urinary immune cells correlated with the pathology or were predictive of disease activity. Corresponding evidence and analysis are absent for ICI-mediated immune nephritis. We report the first investigation analyzing immune cell profiles of matched kidney biopsies and urine of patients with ICI-AKI. We demonstrated the presence of urinary T cells in patients with immune nephritis by flow cytometry analysis. Clonotype analysis of T cell receptor (TCR) sequences confirmed enrichment of kidney TCRs in urine. As ICI therapies become standard of care for more cancers, noninvasively assessing urinary immune cells of ICI therapy recipients can facilitate clinical management and an opportunity to tailor ICI-nephritis treatment.

The role of kidney biopsy in immune checkpoint inhibitor nephrotoxicity

Immune checkpoint inhibitors, medications that boost host immune response to tumor cells, are now at the forefront of anti-cancer therapy. While efficacious in the treatment of patients with advanced cancer, immune checkpoint inhibitors can lead to serious autoimmune side effects involving any organ in the body. Immune checkpoint inhibitor nephrotoxicity is an increasingly recognized cause of acute kidney injury in patients with cancer. This review discusses the clinical and histopathologic diagnosis of immune checkpoint inhibitor nephrotoxicity, highlighting the need for more reliable non-invasive diagnostic testing. We focus on the controversy surrounding the role of kidney biopsy in diagnosis and management of suspected immune checkpoint inhibitor toxicity with inclination toward pursuing kidney biopsy in certain outlined circumstances. Finally, we briefly discuss treatment of immune checkpoint inhibitor nephrotoxicity and the decision to re-challenge immunotherapy in patients who experience these adverse events.

Challenging Dermatologic Considerations Associated with Immune Checkpoint Inhibitors

Immune checkpoint inhibitors have emerged as a new paradigm in oncologic care for many malignancies. However, nonspecific immune activation has led to "collateral damage" in the form of immune-related adverse events, with skin being a commonly affected organ. Cutaneous immune-related adverse events include a wide spectrum of clinical presentations and challenging considerations, often necessitating dermatology referral to support diagnosis and management, particularly for atypical presentations or more severe, cutaneous immune-related adverse events that may require specialized dermatologic evaluations including biopsy and histopathology. Close collaborations between oncologists and dermatologists may optimize clinical decision making in the following challenging management settings: non-steroidal therapies for corticosteroid-refractory, cutaneous immune-related adverse events, immune checkpoint inhibitor rechallenge, balancing cutaneous immune-related adverse events and treatments, and immune checkpoint inhibitors in patients with pre-existing autoimmune disease, skin conditions, and organ transplants. These complex clinical decisions that often lack rigorous data should be made in close collaboration with dermatologists to minimize unnecessary morbidity and mortality. This article provides a review of approaches to challenging dermatologic considerations associated with immune checkpoint inhibitor therapies.

Immune Checkpoint Inhibitors Induced Hepatotoxicity; Gastroenterologists' Perspectives

BACKGROUND: Immune checkpoint inhibitors (ICIs) have promising clinical activity and are essential medications for patients with several malignancies. However, by deranging the immune system, these novel agents could lead to immune-related adverse events (IRAEs). Hepatotoxicity with checkpoint inhibitors usually results in acute hepatitis or drug-induced liver injury. METHODS: This review article discusses the recent clinical evidence available regarding checkpoint inhibitor-induced hepatitis and reviews an approach to their diagnosis and management. CONCLUSION: ICIs have improved patients' outcomes with different forms of malignancy; however, ICIs-related liver damage is a clinically significant entity in these patients. All patients should be monitored carefully for IRAEs while undergoing treatment with ICIs.

Immune-related adverse events in various organs caused by immune checkpoint inhibitors

Current cancer immunotherapies target immune checkpoint molecules such as the inhibitory receptor programmed cell death-1 (PD-1), one of its ligands, programmed cell death ligand-1 (PD-L1), and cytotoxic T-lymphocyte antigen 4 (CTLA-4), a competitive ligand for CD28 binding to stimulatory receptors CD80 and CD86. Multiple biological drugs use monoclonal antibodies targeting PD-1, PD-L1 and CTLA-4 as cancer immunotherapies. These are termed immune checkpoint inhibitors (ICIs). However, activation of the immune system by ICIs can induce the development of immune-related adverse events (irAEs), which can affect multiple organ systems. The most frequent irAEs are cutaneous and mimic various types of spontaneous skin disorders. Most irAEs are classified as autoimmune conditions mediated by ICI-activated CD8⁺ cytotoxic T cells, some of which are also related to activated B cells and production of pathogenic antibodies. Interestingly, blockade of CTLA-4 mainly induces activation of T cells and inhibition of T_reg cells. On the other hand, the mechanisms underlying anti-PD-1/PD-L1 ICI-induced irAEs are more complicated. PD-1 is a receptor expressed on T and B cells, which binds not only PD-L1, but also PD-L2. The role of PD-L1 is dominant in Th1 and Th17 immunity, while PD-L2 works mainly in Th2 immunity. Better understanding of the mechanisms underlying irAEs will allow for better management of irAEs and improve outcomes and quality of life in cancer patients.

Tracheobronchial chondritis as an immune-related adverse event occurring during the administration of nivolumab for recurrent hypopharyngeal squamous cell carcinoma

Tracheobronchial chondritis is a rare immune-related adverse event (irAE) associated with immune checkpoint inhibitors. We report a case wherein tracheobronchial chondritis occurred while administering nivolumab for recurrent hypopharyngeal squamous cell carcinoma (SCC) in a man diagnosed with T2N3bM0 stage IVB hypopharyngeal SCC. After treatment with cisplatin and radiotherapy followed by left and right neck dissection, local recurrence was observed in the hypopharynx. Because of the difficulty of salvage surgery, we administered 240 mg/body of nivolumab. After 9 cycles of nivolumab, the patient was judged to have complete response. After 10 cycles, he had cough and sputum, for which prompting us to perform imaging tests. Computed tomography (CT) showed edematous thickening around the trachea and bilateral bronchi and elevated amounts of adjacent subcutaneous fat tissue. Positron emission tomography-CT showed diffuse fluorodeoxyglucose uptake in the trachea and bilateral bronchi, bronchial endoscopy showed redness and swelling throughout the bronchi, and biopsy showed partial mucosal erosion, inflammatory cell (lymphocyte) infiltration, interstitial edema, and desmoplasia. The patient was diagnosed with tracheobronchial chondritis as an irAE resulting from administering anti-programmed death-1 monoclonal antibody. After four-day prednisolone treatment, his cough and sputum disappeared; after two weeks, tracheobronchial chondritis no longer appeared on CT.

Recommendations for standardizing biopsy acquisition and histological assessment of immune checkpoint inhibitor-associated colitis

Immune checkpoint inhibitor-associated colitis (ICIC) affects approximately 15% of cancer patients treated with immunotherapy. Although histological evaluation is potentially valuable for both the diagnosis of ICIC and evaluation of disease activity, use in clinical practice is heterogeneous. We aimed to develop expert recommendations to standardize histological assessment of disease activity in patients with ICIC. Using the modified Research and Development/University of California Los Angeles (RAND/UCLA) appropriateness methodology, an international panel of 11 pathologists rated the appropriateness of 99 statements on a 9-point Likert scale during two rounds of anonymous voting. Results were discussed between rounds using moderated videoconferences. There are currently no disease-specific instruments for assessing histological features of ICIC. The panel considered that colonoscopy with at least three biopsies per segment from a total of at least five segments, including both endoscopically normal and inflamed areas, was appropriate for tissue acquisition. They agreed that biopsies should be oriented such that the long axis of the colonic crypts is visualized and should be stained with hematoxylin and eosin. Histological items that the panel voted were appropriate to evaluate in ICIC included the degree of structural/architectural change, chronic inflammatory infiltrate, lamina propria and intraepithelial neutrophils, crypt abscesses and destruction, erosions/ulcerations, apoptosis, surface intraepithelial lymphocytosis, and subepithelial collagen thickness. The appropriateness of routine immunohistochemistry was uncertain. These expert recommendations will help standardize assessment of histological activity in patients with ICIC. The panel also identified the development and validation of an ICIC-specific histological index as a research priority.

[Research Progress of Immune Checkpoint Inhibitor-associated Myocarditis]

免疫检查点抑制剂（immune checkpoint inhibitors, ICIs）是一种负性调节因子抗体，激活T细胞发挥免疫治疗抗肿瘤作用的同时，也可引起免疫相关的不良应答，从而诱导出一系列免疫相关不良反应（immune related adverse events, irAEs）。在这些irAEs中，ICIs相关心肌炎的发病率虽然很低，但致死率却明显高于其他不良反应，接近50%，临床医生应用ICIs时应提高警惕，但目前ICIs相关心肌炎的发病机制仍不明确。本文结合近期ICIs的研究成果对ICIs相关性心肌炎的发生机制及临床表现等方面作一综述，以提高临床医生对该不良反应的认识。

Immune checkpoint inhibitors and cardiotoxicity: possible mechanisms, manifestations, diagnosis and management

INTRODUCTION

Immune checkpoint inhibitors (ICIs) are a new class of anticancer drugs that enhance the immune system function and activate T cells against cancerous cells. Although cardiac complications are not common, they could be accompanied with high morbidity and mortality.

AREAS COVERED

Regarding the importance of cardiac complications and their subsequent burden on individuals and the healthcare system, this review attempts to discuss the mechanism, diagnosis, and management of myocarditis, besides recapitulating the possible mechanism of other cardiac adverse events. Moreover, we briefly discuss the concurrent administration of other chemotherapeutic agents.

EXPERT OPINION

Due to insufficient knowledge concerning the physiopathology of immune-related adverse events (irAEs) and their potential further complications, cardiovascular complications in particular and in the context of this paper's focus, cooperation of oncologists, immunologists, and cardiologists is necessary for the management of patients. Experimental approaches such as using corticosteroids are becoming a part of guidelines for managing cardiac irAEs. However, a unique algorithm for diagnosis and management is necessary, especially in myocarditis cases. Furthermore, more studies are required to resolve current challenges, including prevention of myocarditis, concurrent administration of other chemotherapeutic agents, and re-introducing patients with ICIs.

Immunotherapy in hepatocellular carcinoma: evaluation and management of adverse events associated with atezolizumab plus bevacizumab

In light of positive efficacy and safety findings from the IMbrave150 trial of atezolizumab plus bevacizumab, this novel combination has become the preferred first-line standard of care for patients with unresectable hepatocellular carcinoma (HCC). Several additional trials are ongoing that combine an immune checkpoint inhibitor with another agent such as a multiple kinase inhibitor or antiangiogenic agent. Therefore, the range of first-line treatment options for unresectable HCC is likely to increase, and healthcare providers need succinct information about the use of such combinations, including their efficacy and key aspects of their safety profiles. Here, we review efficacy and safety data on combination immunotherapies and offer guidance on monitoring and managing adverse events, especially those associated with atezolizumab plus bevacizumab. Because of their underlying liver disease and high likelihood of portal hypertension, patients with unresectable HCC are at particular risk of gastrointestinal bleeding, and this risk may be exacerbated by treatments that include antiangiogenic agents. Healthcare providers also need to be alert to the risks of proteinuria and hypertension, colitis, hepatitis, and reactivation of hepatitis B or C virus infection. They should also be aware of the possibility of rarer but potentially life-threatening adverse events such as pneumonitis and cardiovascular events. Awareness of the risks associated with these therapies and knowledge of adverse event monitoring and management will become increasingly important as the therapeutic range broadens in unresectable HCC.

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.

A Review of Cancer Immunotherapy Toxicity: Immune Checkpoint Inhibitors

Cancer immunotherapy, which leverages features of the immune system to target neoplastic cells, has revolutionized the treatment of cancer. The use of these therapies has rapidly expanded in the past two decades. Immune checkpoint inhibitors represent one drug class within immunotherapy with its first agent FDA-approved in 2011. Immune checkpoint inhibitors act by disrupting inhibitory signals from neoplastic cells to immune effector cells, allowing activated T-cells to target these neoplastic cells. Unique adverse effects associated with immune checkpoint inhibitors are termed immune-related adverse effects (irAEs) and are usually immunostimulatory in nature. Almost all organ systems may be affected by irAEs including the dermatologic, gastrointestinal, pulmonary, endocrine, and cardiovascular systems. These effects range from mild to life-threatening, and their onset can be delayed several weeks or months. For mild irAEs, symptomatic care is usually sufficient. For higher grade irAEs, discontinuation of therapy and initiation of immunosuppressive therapy may be necessary. The management of patients with irAEs involves multidisciplinary care coordination with respect to the long-term goals the individual patient. Clinicians must be aware of the unique and sometimes fatal toxicologic profiles associated with immunotherapies to ensure prompt diagnosis and appropriate management.

Hypersensitivity reactions and anaphylaxis to checkpoint inhibitor-monoclonal antibodies and desensitization

OBJECTIVE

To review type 1 hypersensitivity reactions and anaphylaxis to checkpoint inhibitor-monoclonal antibodies and its management with drug desensitization.

DATA SOURCES

English-language literature on MEDLINE regarding hypersensitivity, anaphylaxis, and checkpoint inhibitor-monoclonal antibodies.

STUDY SELECTIONS

References were selected based on relevance, novelty, robustness, and applicability.

RESULTS

There are well-known tissue toxicities associated to checkpoint inhibitors, but hypersensitivity reactions and anaphylaxis have been underreported. The presentation of these reactions is based on clinical phenotypes with underlying endotypes identified by specific biomarkers. Drug desensitizations have been successfully applied to checkpoint inhibitor drugs to allow patients with cancer to receive first-line therapies. This review provides current best practices for the recognition and diagnosis of hypersensitivity reactions and anaphylaxis to checkpoint inhibitors and their management using drug desensitization.

CONCLUSION

Hypersensitivity reactions and anaphylaxis have been identified as potential adverse effects induced by checkpoint inhibitor-monoclonal antibodies. Drug desensitization is a safe and effective treatment option for patients who experience hypersensitivity reactions in need of these monoclonal antibodies to improve cancer outcomes.

Adverse events induced by immune checkpoint inhibitors

Immune checkpoint inhibitors have revolutionized the treatments of cancers but are also associated with immune related adverse events that can interfere with their use. The types and severity of adverse events vary with checkpoint inhibitors. A single mechanism of pathogenesis has not emerged: postulated mechanisms involve direct effects of the checkpoint inhibitor, emergence of autoantibodies or autoreactive T cells, and destruction by toxic effects of activated T cells. Several host factors such as genotypes, preexisting autoimmune disease, inflammatory responses and others may have predictive value. Ongoing investigations seek to identify ways of modulating the autoimmunity without affecting the anti-tumor response with agents that are specific for the autoimmune mechanisms.

Anti-PD-1-Induced Hidradenitis Suppurativa

Mucocutaneous adverse events are commonly observed under immune checkpoint inhibitors (ICIs) therapy. Here, we report the case of a 43-year-old male patient with a stage IIIC melanoma disease who developed hidradenitis suppurativa (HS) three months after the beginning of an anti-PD-1 (nivolumab) adjuvant therapy. The patient had no comorbidities other than obesity and severe acne during adolescence. After an unsuccessful course of lymecycline while he was still treated with nivolumab, he gradually improved under zinc gluconate therapy and, more importantly, after nivolumab cessation. HS is a recurrent follicular inflammatory disease in the apocrine gland-bearing areas of the body often associated with obesity, metabolic syndrome, tobacco smoking, inflammatory bowel diseases, psoriasis, and arthritis. In our patient, the latency period between drug initiation and onset of HS symptoms and the improvement after immunotherapy discontinuation, argued strongly in favor of an anti-PD-1-induced HS. Anti-PD-1 therapies often trigger T cells-mediated adverse events that mimic Th17-mediated inflammatory and neutrophilic diseases. We suggest that HS, as other pustular skin reactions and ICIs-induced neutrophilic colitis, can be part of the anti-PD-1 mucocutaneous adverse event spectrum.

A novel mouse model for checkpoint inhibitor-induced adverse events

Immune checkpoint inhibitors have demonstrated significant efficacy in the treatment of a variety of cancers, however their therapeutic potential is limited by abstruse immune related adverse events. Currently, no robust animal model exists of checkpoint inhibitor-induced adverse events. Establishing such a model will improve our mechanistic understanding of this process, which in turn will inform design of improved therapies. We developed a mouse model to determine inflammatory toxicities in response to dual checkpoint blockade in the presence of syngeneic tumors. Mice from susceptible genetic backgrounds received intraperitoneal injections of anti-mouse PD-1 and CTLA-4 antibodies. The mice were monitored for weight loss and histologic evidence of inflammation. Blood was collected for basic metabolic panels and titers of anti-nuclear antibodies. In parallel, mice were also treated with prednisolone, which is commonly used to treat immune related adverse events among cancer patients. Among all the genetic backgrounds, B6/lpr mice treated with anti-CTLA-4 and anti-PD-1 antibodies developed more substantial hepatitis, pancreatitis, colitis, and pneumonitis characterized by organ infiltration of immune cells. Mice that developed tissue infiltration demonstrated high serum levels of glucose and high titers of anti-nuclear antibodies. Finally, while administration of prednisolone prevented the development of the inflammatory adverse events, it also abrogated the protective anti-tumor effect of the checkout inhibitors. Genetic background and treatment modalities jointly modified the inflammatory adverse events in tumor bearing mice, suggesting a complex mechanism for checkpoint inhibitor-related inflammation. Future studies will assess additional genetic susceptibility factors and will examine possible contributions from the administration of other anti-inflammatory drugs.

Malignant Melanoma of the Gastrointestinal Tract: Symptoms, Diagnosis, and Current Treatment Options

Malignant melanoma (MM) has become the fifth most frequent cancer in the UK. It is the most common carcinoma to metastasize to the gastrointestinal (GI) tract. MM particularly has an affinity to spread to the small bowel, which is followed by the involvement of the stomach and large intestine. Excellent endoscopic options including video capsule endoscopy and enteroscopy are available for a precise diagnosis of GI involvement by a metastatic MM. The complete surgical resection of GI metastatic MM in carefully selected patients not only provides symptom control, but has also been associated with an increase in overall survival. The approval of BRAF-targeted therapies and immune checkpoint inhibitors has transformed therapeutic approaches for patients with metastatic MM over the past decade. Currently, the overall survival of patients with advanced metastatic MM who have been treated with a combination of immunotherapeutic agents reaches 52% at five years. The role of surgery for patients with the metastatic involvement of the GI tract with MM is evolving in the era of effective systemic treatments.

Atezolizumab-induced Sclerosing Cholangitis in a patient with lung cancer: A case report

Atezolizumab is an immune checkpoint inhibitor that is a key drug in non-small-cell lung cancer treatment. However, it can cause immune-related adverse events, including liver injury. Several patterns of liver injury associated with immune checkpoint inhibitor therapy have been reported; however, not much is known about sclerosing cholangitis. We present here a case of lung adenocarcinoma with atezolizumab-induced secondary sclerosing cholangitis diagnosed using needle biopsy of the liver. A 77-year-old woman with lung adenocarcinoma, cT3N2M0, stage IIIA, was treated with concurrent chemoradiotherapy involving carboplatin and paclitaxel, which markedly reduced the tumor diameter. However, 5 months later, the lesion regrew, and she underwent 39 cycles of pemetrexed monotherapy. As pulmonary metastasis progressed, she was treated with atezolizumab. After 13 cycles of atezolizumab therapy, she complained of nausea. Laboratory tests showed elevated levels of the biliary tract and hepatic enzymes. Nevertheless, abdominal computed tomography and ultrasonography revealed no underlying related cause. Ultrasound-guided needle biopsy of the liver was performed, and histopathological analysis of biopsy samples showed features of sclerosing cholangitis. Further examinations were performed, and a diagnosis of atezolizumab-induced secondary sclerosing cholangitis without strictures and dilatations of the large bile ducts was established. Prednisolone was administered orally, after which the biliary tract and hepatic enzyme levels improved immediately. In patients presenting with a hepatic injury during immune checkpoint inhibitor therapy, clinicians should be aware of the possibility of immune checkpoint inhibitor-induced sclerosing cholangitis, even if the large bile ducts have no strictures and dilatations.

Primary Biliary Cirrhosis and Granulomatous Hepatitis After Immune Checkpoint Blockade in Patients With Metastatic Melanoma: Report of 2 Cases and Literature Discussion

Immune-related adverse events (irAEs) of immune checkpoint inhibitors can potentially affect every organ system, are sometimes challenging, and require a multidisciplinary approach. Most common irAEs are very well characterized, but some other such rare autoimmune liver diseases are probably underdiagnosed and less explored. We present here the case of a 69-year-old man with metastatic melanoma developing a severe primary biliary cirrhosis under pembrolizumab, and of a 52-year-old woman with metastatic melanoma with granulomatous hepatitis in the context of an immune-related multiorgan inflammatory reaction due to ipilimumab and nivolumab. Both cases were in part steroid refractory and required a complex diagnostic assessment and long-term therapeutic management. The liver biopsy was crucial for ensuring a correct diagnosis. Clinicians should be aware of rare liver diseases in the context of increased liver enzymes under immune checkpoint inhibitors, especially if not responding to corticosteroids. The primary diagnostic workup should localize the liver damage (biliary or parenchymal) and distinguish irAEs from other pathologic conditions such as metastasis, second benign and malignant tumors, viral hepatitis, and cholelithiasis. If in doubt, a liver biopsy should be performed. Early diagnosis and accurate assessment of hepatic adverse events is necessary for prompt and effective treatment, with reduction of inappropriate discontinuation of immunotherapy, morbidity, and mortality.

Role of PD-L1 in Gut Mucosa Tolerance and Chronic Inflammation

The gastrointestinal (GI) mucosa is among the most complex systems in the body. It has a diverse commensal microbiome challenged continuously by food and microbial components while delivering essential nutrients and defending against pathogens. For these reasons, regulatory cells and receptors are likely to play a central role in maintaining the gut mucosal homeostasis. Recent lessons from cancer immunotherapy point out the critical role of the B7 negative co-stimulator PD-L1 in mucosal homeostasis. In this review, we summarize the current knowledge supporting the critical role of PD-L1 in gastrointestinal mucosal tolerance and how abnormalities in its expression and signaling contribute to gut inflammation and cancers. Abnormal expression of PD-L1 and/or the PD-1/PD-L1 signaling pathways have been observed in the pathology of the GI tract. We also discuss the current gap in our knowledge with regards to PD-L1 signaling in the GI tract under homeostasis and pathology. Finally, we summarize the current understanding of how this pathway is currently targeted to develop novel therapeutic approaches.

Immune Checkpoint Inhibition-Does It Cause Rheumatic Diseases? Mechanisms of Cancer-Associated Loss of Tolerance and Pathogenesis of Autoimmunity

Mechanisms of immune checkpoints and their role in autoimmunity are discussed in the context of immune checkpoint inhibitor (ICI) therapy for cancer. The updated clinical spectrum of immune-related adverse events (irAEs), with an in-depth discussion of rheumatic irAEs, is presented. The relationship between ICI-induced loss of self-tolerance in cancer and the implications for understanding of irAEs, rheumatic irAEs in particular, is overviewed.

British Society of Gastroenterology endorsed guidance for the management of immune checkpoint inhibitor-induced enterocolitis

Immune checkpoint inhibitors are a novel class of cancer treatment that have improved outcomes for a subset of cancer patients. They work by antagonising inhibitory immune pathways, thereby augmenting immune-mediated antitumour responses. However, immune activation is not cancer-specific and often results in the activation of immune cells in non-cancer tissues, resulting in off-target immune-mediated injury and organ dysfunction. Diarrhoea and gastrointestinal tract inflammation are common and sometimes serious side-effects of this type of therapy. Prompt recognition of gastrointestinal toxicity and, in many cases, rapid institution of anti-inflammatory or biologic therapy (or both) is required to reverse these complications. Management of organ-specific complications benefits from multidisciplinary input, including engagement with gastroenterologists for optimal management of immune checkpoint inhibitor-induced enterocolitis. In this British Society of Gastroenterology endorsed guidance document, we have developed a consensus framework for the investigation and management of immune checkpoint inhibitor-induced enterocolitis.