Mucosal inflammation predicts response to systemic steroids in immune checkpoint inhibitor colitis

The Development of Persistent Gastrointestinal Symptoms in Patients With Melanoma Who Have Had an Immune Checkpoint Inhibitor-Related Gastrointestinal Toxicity

INTRODUCTION

Immune-related adverse events (irAE) secondary to immune checkpoint inhibitors (ICI) have gastrointestinal (GI) manifestations, including gastritis, enteritis, and/or colitis. The long-term sequelae of ICI-associated GI toxicities (GI-irAE), particularly the development of disorders of gut-brain interaction, are not well known. We characterized the incidence of persistent GI symptoms after GI-irAE.

METHODS

This is a retrospective study of adults with melanoma treated with ICI and diagnosed with GI-irAE at our institution from 2013 to 2021. All patients had endoscopic and histologic evidence of GI-irAE. The primary outcome was incidence of persistent GI symptoms (diarrhea, abdominal pain, bloating, constipation, fecal incontinence, nausea, vomiting) after resolution of GI-irAE. Hazard ratios evaluated the association between parameters and time to persistent GI symptoms.

RESULTS

One hundred four patients with melanoma (90% stage IV disease) and GI-irAE met inclusion criteria. Thirty-four percent received anti-cytotoxic T lymphocyte-associated protein-4 therapy, 33% anti-programmed death-1, and 34% dual therapy. Patients were treated for GI-irAE for an average of 9 ± 6 weeks. Twenty-eight (27%) patients developed persistent GI symptoms 1.6 ± 0.8 years after GI-irAE. The most common symptom was constipation (17%), followed by bloating (8%) and diarrhea (5%). Over 453 person-years, the incident rate was 6.2% per 100 person-years. Use of cytotoxic T lymphocyte-associated protein-4 single or dual therapy was associated with a 3.51× risk of persistent GI symptoms (95% confidence interval 1.20-10.23).

DISCUSSION

In this cohort of melanoma patients who experienced GI-irAE, 26% developed persistent GI symptoms, most frequently constipation. Future studies should characterize the GI sequelae after GI-irAE, which may shed light on disorders of gut-brain interaction pathogenesis and improve the lives of cancer survivors.

Review article: Contemporary management of gastrointestinal, pancreatic and hepatic toxicities of immune checkpoint inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICIs) are effective oncologic agents which frequently cause immune-related adverse events (irAEs) which can impact multiple organ systems. Onco-Gastroenterology is a novel and emerging subspecialty within gastroenterology focused on cancer treatment-related complications. Gastroenterologists must be prepared to identify and manage diverse immune-mediated toxicities including enterocolitis, hepatitis, pancreatitis and other ICI-induced toxicities.

AIM

To provide a narrative review of the epidemiology, diagnostic evaluation and management of checkpoint inhibitor-induced gastrointestinal and hepatic toxicities.

METHODS

We searched Cochrane and PubMed databases for articles published through August 2023.

RESULTS

Gastrointestinal and hepatic irAEs include most commonly enterocolitis and hepatitis, but also pancreatitis, oesophagitis, gastritis, motility disorders (gastroparesis) and other rarer toxicities. Guidelines from the National Comprehensive Cancer Network, American Society of Clinical Oncology and European Society for Medical Oncology, in combination with emerging cohort and clinical trial data, offer strategies for management of ICI toxicities. Evaluation of irAEs severity by formal classification and clinical stability, and a thorough workup for alternative etiologies which may clinically mimic irAEs underlie initial management. Treatments include corticosteroids, biologics and other immunosuppressive agents plus supportive care; decisions on dosing, timing and choice of steroid adjuncts and potential for subsequent checkpoint inhibitor dosing are nuanced and toxicity-specific.

CONCLUSIONS

Expanding clinical trial and cohort data have clarified the epidemiology and clinical characteristics of gastrointestinal, pancreatic and hepatic toxicities of ICIs. Guidelines, though valuable, remain based principally on retrospective cohort data. Quality prospective, controlled studies may refine algorithms for treatment and potential immunotherapy rechallenge.

Colitis due to cancer treatment with immune check-point inhibitors - review of literature and presentation of clinical cases

Treatment with immune checkpoint inhibitors is effective in various cancers, but may be associated with immune-mediated side effects in other organs. Among the more common ones is gastrointestinal tract involvement, especially colitis. In most patients, colitis is mild or responds to corticosteroid treatment. A smaller proportion of patients, more often those treated with cytotoxic T lymphocyte antigen-4 inhibitors, may have a more severe course of colitis, even life-threatening complications. In these patients, prompt action, timely diagnosis with endoscopic evaluation and early treatment with high-dose corticosteroids and, if ineffective, rescue therapy with biologic agents such as infliximab and vedolizumab are needed. We present three cases from our clinical practice, data on incidence and clinical presentation, current recommendations regarding diagnostic approach and treatment of immune checkpoint inhibitors induced colitis.

Management of liver and gastrointestinal toxicity induced by immune checkpoint inhibitors: Position statement of the AEEH-AEG-SEPD-SEOM-GETECCU

The development of the immune checkpoint inhibitors (ICI) is one of the most remarkable achievements in cancer therapy in recent years. However, their exponential use has led to an increase in immune-related adverse events (irAEs). Gastrointestinal and liver events encompass hepatitis, colitis and upper digestive tract symptoms accounting for the most common irAEs, with incidence rates varying from 2% to 40%, the latter in patients undergoing combined ICIs therapy. Based on the current scientific evidence derived from both randomized clinical trials and real-world studies, this statement document provides recommendations on the diagnosis, treatment and prognosis of the gastrointestinal and hepatic ICI-induced adverse events.

Clinical Management of Gastrointestinal and Liver Toxicities of Immune Checkpoint Inhibitors

Immune checkpoint inhibitors have transformed the treatment paradigm for various types of cancer. Nonetheless, with the utilization of these groundbreaking treatments, immune-related adverse events (irAEs) are increasingly encountered. Colonic and hepatic involvement are among the most frequently encountered irAEs. Drug-induced side effects, infectious causes, and tumor-related symptoms are the key differentials for irAE complications. Potential risk factors for the development of irAEs include combination use of immune checkpoint inhibitors, past development of irAEs with other immunotherapy treatments, certain concomitant drugs, and a pre-existing personal or family history of autoimmune illness such as inflammatory bowel disease. The importance of early recognition, timely and proper management cannot be understated, as there are profound clinical implications on the overall cancer treatment plan and prognosis once these adverse events occur. Herein, we cover the clinical management of the well-established gastrointestinal irAEs of enterocolitis and hepatitis, and also provide an overview of several other emerging entities.

New strategies in the diagnosis and treatment of immune-checkpoint inhibitor-mediated colitis

Immune-checkpoint inhibitor-mediated colitis (IMC) is an increasingly recognized adverse event in cancer immunotherapy, particularly associated with immune checkpoint inhibitors (ICIs) such as anti-cytotoxic T-lymphocyte antigen-4 and anti-programmed cell death protein-1 antibodies. As this revolutionary immunotherapy gains prominence in cancer treatment, understanding, diagnosing, and effectively managing IMC becomes paramount. IMC represents a unique challenge due to its immune-mediated nature and potential for severe complications. However, a precise picture of IMC pathophysiology is currently unavailable. Therefore, we aimed to summarize the existing data while acknowledging the need for further research. This comprehensive review explores the mechanisms underlying ICIs, gastrointestinal adverse effects, and, in particular, IMC's incidence, prevalence, and features. Our review also emphasizes the importance of recognizing IMC's distinct clinical and histopathological features to differentiate it from other forms of colitis. Furthermore, this paper highlights the urgent need for evolving diagnostic methods, therapeutic strategies, and a multidisciplinary approach to effectively manage IMC.

Management of liver and gastrointestinal toxicity induced by immune checkpoint inhibitors: Position statement of the AEEH-AEG-SEPD-SEOM-GETECCU

The development of the immune checkpoint inhibitors (ICI) is one of the most remarkable achievements in cancer therapy in recent years. However, their exponential use has led to an increase in immune-related adverse events (irAEs). Gastrointestinal and liver events encompass hepatitis, colitis and upper digestive tract symptoms accounting for the most common irAEs, with incidence rates varying from 2 % to 40 %, the latter in patients undergoing combined ICIs therapy. Based on the current scientific evidence derived from both randomized clinical trials and real-world studies, this statement document provides recommendations on the diagnosis, treatment and prognosis of the gastrointestinal and hepatic ICI-induced adverse events.

Sargramostim for Prophylactic Management of Gastrointestinal Immune-Related Adverse Events of Immune Checkpoint Inhibitor Therapy for Cancer

Immune checkpoint inhibitor (ICI) therapy improves outcomes in several cancers. Unfortunately, many patients experience grade 3-4 treatment-related adverse events, including gastrointestinal (GI) toxicities which are common. These GI immune-related adverse events (irAEs) induced by ICIs present significant clinical challenges, require prompt intervention, and result in treatment delays or discontinuations. The treatment for these potentially severe and even fatal GI irAEs which include enterocolitis, severe diarrhea, and hepatitis may interfere with the anti-cancer approach. Sargramostim (glycosylated, yeast-derived, recombinant human GM-CSF) is an agent that has been used in clinical practice for more than 30 years with a well-recognized safety profile and has been studied in many therapeutic areas. The mechanism of action of sargramostim may treat moderate-to-severe GI irAEs without impairing the anti-cancer therapy. Some early data also suggest a potential survival benefit. Through the differentiation/maturation of monocytes, macrophages, and neutrophils and induction of anti-inflammatory T cell responses, GM-CSF aids in GI homeostasis, mucosal healing, and mucosal immunity. GM-CSF knockout mice are susceptible to severe colitis which was prevented with murine GM-CSF administration. For some patients with GI mucosa and immune cell function impairment, e.g., Crohn's disease, sargramostim reduces disease severity. In a prospective, randomized study (ECOG 1608), advanced melanoma patients had a reduction in grade 3-5 GI irAEs and less frequent colonic perforation in the sargramostim plus ipilimumab arm compared to ipilimumab alone. Sargramostim continues to be studied with ICIs for the prophylactic management of irAEs while also potentially providing a survival benefit.

Corticosteroid-resistant immune-related adverse events: a systematic review

Immune checkpoint inhibitor (ICI) treatment has become an important therapeutic option for various cancer types. Although the treatment is effective, ICI can overstimulate the patient's immune system, leading to potentially severe immune-related adverse events (irAEs), including hepatitis, colitis, pneumonitis and myocarditis. The initial mainstay of treatments includes the administration of corticosteroids. There is little evidence how to treat steroid-resistant (sr) irAEs. It is mainly based on small case series or single case reports. This systematic review summarizes available evidence about sr-irAEs. We conducted a systematic literature search in PubMed. Additionally, we included European Society for Medical Oncology, Society for Immunotherapy of Cancer, National Comprehensive Cancer Network and American Society of Clinical Oncology Guidelines for irAEs in our assessment. The study population of all selected publications had to include patients with cancer who developed hepatitis, colitis, pneumonitis or myocarditis during or after an immunotherapy treatment and for whom corticosteroid therapy was not sufficient. Our literature search was not restricted to any specific cancer diagnosis. Case reports were also included. There is limited data regarding life-threatening sr-irAEs of colon/liver/lung/heart and the majority of publications are single case reports. Most publications investigated sr colitis (n=26), followed by hepatitis (n=21), pneumonitis (n=17) and myocarditis (n=15). There is most data for mycophenolate mofetil (MMF) to treat sr hepatitis and for infliximab, followed by vedolizumab, to treat sr colitis. Regarding sr pneumonitis there is most data for MMF and intravenous immunoglobulins (IVIG) while data regarding infliximab are conflicting. In sr myocarditis, most evidence is available for the use of abatacept or anti-thymocyte globulin (ATG) (both with or without MMF) or ruxolitinib with abatacept. This review highlights the need for prompt recognition and treatment of sr hepatitis, colitis, pneumonitis and myocarditis. Guideline recommendations for sr situations are not defined precisely. Based on our search, we recommend-as first line treatment-(1) MMF for sr hepatitis, (2) infliximab for sr colitis, followed by vedolizumab, (3) MMF and IVIG for sr pneumonitis and (4) abatacept or ATG (both with or without MMF) or ruxolitinib with abatacept for sr myocarditis. These additional immunosuppressive agents should be initiated promptly if there is no sufficient response to corticosteroids within 3 days.

Prevalence of Enteric Infections in Patients on Immune Checkpoint Inhibitors and Impact on Management and Outcomes

BACKGROUND

Stool pathogen testing is recommended as part of the initial evaluation for patients with new-onset diarrhea on immune checkpoint inhibitors (ICIs), yet its significance has not been well-studied. We aimed to determine the impact of multiplex gastrointestinal (GI) pathogen PCR testing on the clinical course and use of immunosuppressive therapy in patients who develop diarrhea on ICIs.

METHODS

This retrospective cohort included individuals who underwent GI pathogen panel PCR for diarrhea on ICIs at Memorial Sloan Kettering between 7/2015 and 7/2021. The primary outcome was use of immunosuppressive therapy for suspected immunotherapy-related enterocolitis (irEC). Secondary outcomes included diarrhea severity and endoscopic and histologic disease patterns.

RESULTS

Among 521 ICI-treated patients tested for GI pathogens, 61 (11.7%) had a positive PCR. Compared to patients without detectable infections, patients with infections had more frequent grades 3-4 diarrhea (37.7% vs. 19.6%, P < .01) and colitis (39.3% vs. 14.7%, P < .01). However, patients with infections did not have higher rates of persistent or recurrent diarrhea and were less likely to receive steroids (P < .01) and second-line immunosuppressive agents (P = .03). In 105 patients with lower endoscopy, similar trends were observed and no differences in endoscopic severity or histologic patterns were noted between groups.

CONCLUSIONS

GI infections in ICI-treated patients presenting with diarrhea are linked to more severe but self-limited clinical presentations and may be optimally treated with observation and supportive care alone. Routine and timely stool pathogen testing may help avert unnecessary empiric immunosuppression for suspected irEC, which has been linked to blunted antitumor responses and numerous adverse effects.

The colitis may be microscopic, but the diarrhea is not: update on the treatment of microscopic colitis and immune checkpoint inhibitor colitis

PURPOSE OF REVIEW

Microscopic colitis is an inflammatory disease of the colon that presents as watery diarrhea with minimal to normal endoscopic changes on colonoscopy. It encompasses two common subtypes, lymphocytic colitis and collagenous colitis, which are both treated similarly.Immune checkpoint inhibitor colitis is among the most common immune-related adverse events. Endoscopic and histological findings range from normal colonic mucosa to inflammatory bowel like changes. This review article provides update in treatment and management of microscopic colitis and immune checkpoint inhibitor colitis (ICPi colitis).

RECENT FINDINGS

Recent studies on microscopic colitis have focused on the successful use of immunomodulators such as biologics for treatment of budesonide refractory microscopic colitis cases. Microscopic colitis does not confer an added risk for colorectal cancer.With the increasing usage of immunotherapy agents, immune checkpoint inhibitor colitis is becoming more common. ICPi colitis can be successfully managed with steroids, with treatment stepped up to biologics for moderate to severe cases or for mild cases that do not respond to steroids. Immunotherapy agents can be carefully re-introduced in mild cases, after treatment of ICPi colitis.

SUMMARY

Biologics can be used to treat budesonide refractory microscopic colitis. ICPi colitis can be managed with steroids and biologics in moderate to severe cases.

Treatment and outcomes of immune checkpoint inhibitors-associated colitis/diarrhea: A systematic review and meta-analysis

BACKGROUND

Immune checkpoint inhibitors (ICIs) have improved the outcomes of cancer patients. However, ICIs often lead to colitis/diarrhea. This study aimed to assess the treatment of ICIs-associated colitis/diarrhea and outcomes.

METHODS

PubMed, EMBASE, and Cochrane Library databases were searched for eligible studies which investigated the treatment and outcomes of colitis/diarrhea developing in patients who received ICIs. The pooled incidences of any-grade colitis/diarrhea, low-grade colitis, high-grade colitis, low-grade diarrhea, and high-grade diarrhea as well as the pooled rates of response to treatment, mortality, and ICIs permanent discontinuation and restarts in patients with ICIs-associated colitis/diarrhea were estimated using a random-effects model.

RESULTS

Among the 11,492 papers initially identified, 27 studies were included. The pooled incidences of any-grade colitis/diarrhea, low-grade colitis, high-grade colitis, low-grade diarrhea, and high-grade diarrhea were 17%, 3%, 17%, 13%, and 15%, respectively. The pooled rates of overall response, response to corticosteroid therapy, and response to biological agents were 88%, 50%, and 96%, respectively. The pooled short-term mortality in patients with ICIs-associated colitis/diarrhea was 2%. The pooled incidences of ICIs permanent discontinuation and restarts were 43% and 33%, respectively.

CONCLUSION

ICIs-associated colitis/diarrhea is common, but rarely lethal. Half of them are responsive to corticosteroid therapy. There is a fairly high rate of response to biological agents in steroid-refractory colitis/diarrhea patients.

Gastrointestinal mucosal toxicities from immune checkpoint inhibitors: Current understanding and future directions

Immune checkpoint inhibitor (ICI) therapy has revolutionized the field of oncology over the past decade, leading to durable remissions in some patients but also producing a wide spectrum of treatment-limiting inflammatory toxicities that are referred to as immune-related adverse events (irAEs). Although irAEs can involve any organ system in the body, they most commonly affect the barrier tissues, including the gastrointestinal tract with colitis and enterocolitis affecting a significant fraction of patients on ICIs. We are beginning to understand the mechanisms that drive ICI colitis, with early experiments indicating a role for CD8+ resident memory T cells (TRMs) in the gut, which become activated and differentiate into cytotoxic cells in response to ICI therapy. The risk factors that define who will develop ICI colitis are not understood and substantial efforts are underway to identify potential biomarkers for risk of this and other toxicities. Optimal management of ICI colitis is also an area of active investigation. Current standard treatments are based largely on small, retrospective analyses, and while drugs like systemic glucocorticoids or the TNFα inhibitor infliximab do appear to be highly active in ICI colitis, the impact of these therapies on antitumor responses is poorly understood. As discussed in this review, future work will have to define the immune mechanisms driving ICI colitis in more detail and in comparison to antitumor responses in order to identify candidate pathways that can be targeted to improve ICI colitis without interfering in antitumor immunity. Studying these interventions will require randomized, controlled trials with both tumor and colitis endpoints, a goal that will necessitate collaboration across institutions and funding agencies. We are at a point where such collaborative trials are feasible, and have the potential to greatly improve the care of patients with ICI colitis as well as other irAEs.

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.

Updates in toxicities associated with immune checkpoint inhibitors

INTRODUCTION

Immune checkpoint inhibitors (ICIs) have become a pillar of treatment for numerous cancers with increasing use in combination with other ICIs and in earlier stages of disease treatment. Although effective, ICI use is accompanied by a milieu of potentially bothersome or even life-threatening toxicities known as immune-related adverse events (irAEs), necessitating careful monitoring and early intervention.

AREAS COVERED

In this review, we provide an overview of recent advances surrounding toxicity pathophysiology and treatment in the context of relevant organ systems. An emphasis on current treatments by toxicity, as well as updates on steroid-refractory toxicities, chronic toxicities, and biomarkers will be a focus of this update on the current understanding of irAEs.

EXPERT OPINION

ICI toxicities are a major limitation on the deployment of multi-agent ICI regimens and are thus a major priority to understand, treat, and prevent. Recent developments have led to greater understanding of the pathophysiology of these events, which may lead to improved prevention or mitigation strategies. Further, early studies have also suggested steroid-sparing approaches that may be useful. Ultimately, preventing and managing irAEs will be a key goal toward successful ICI treatment across a broader range of patients with cancer.

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.

[Drug induced gastro-intestinal tract lesions: A pathologist point of view]

The number of drugs available to clinicians, especially targeted therapies, grows continuously. Some drugs are known to cause frequent digestive adverse effects, which may affect the gastro-intestinal tract in a diffuse or localized manner. Some treatments may leave relatively pathognomonic deposits, but histological lesions of iatrogenic origin are mostly non-specific. The diagnostic and etiological approach is often complex because of these non-specific aspects and also because (1) a single type of drug may cause different histological lesions, (2) different drugs may cause identical histological lesions, (3) the patient may receive different drugs, and (4) drug-induced lesions may mimic other pathological entities such as inflammatory bowel disease, celiac disease, or graft versus host disease. The diagnosis of iatrogenic gastrointestinal tract injury therefore requires close anatomic-clinical correlation. The iatrogenic origin can only be formally established if the symptomatology improves when the incriminating drug is stopped. This review aims to present the different histological patterns of gastrointestinal tract iatrogenic lesions, the potentially incriminate drugs, as well as the histological signs to look for in order to help the pathologist to distinguish an iatrogenic injury from another pathology of the gastrointestinal tract.

Society for Immunotherapy of Cancer (SITC) consensus definitions for immune checkpoint inhibitor-associated immune-related adverse events (irAEs) terminology

Immune-related adverse events (irAEs) associated with immune checkpoint inhibitor (ICI) therapy may vary substantially in their clinical presentation, including natural history, outcomes to treatment, and patterns. The application of clinical guidelines for irAE management can be challenging for practitioners due to a lack of common or consistently applied terminology. Furthermore, given the growing body of clinical experience and published data on irAEs, there is a greater appreciation for the heterogeneous natural histories, responses to treatment, and patterns of these toxicities, which is not currently reflected in irAE guidelines. Furthermore, there are no prospective trial data to inform the management of the distinct presentations of irAEs. Recognizing a need for uniform terminology for the natural history, response to treatment, and patterns of irAEs, the Society for Immunotherapy of Cancer (SITC) convened a consensus panel composed of leading international experts from academic medicine, industry, and regulatory agencies. Using a modified Delphi consensus process, the expert panel developed clinical definitions for irAE terminology used in the literature, encompassing terms related to irAE natural history (ie, re-emergent, chronic active, chronic inactive, delayed/late onset), response to treatment (ie, steroid unresponsive, steroid dependent), and patterns (ie, multisystem irAEs). SITC developed these definitions to support the adoption of a standardized vocabulary for irAEs, which will have implications for the uniform application of irAE clinical practice guidelines and to enable future irAE clinical trials.

Current landscape and tailored management of immune-related adverse events

Unprecedented advances have been made in immune checkpoint inhibitors (ICIs) in the treatment of cancer. However, the overall benefits from ICIs are impaired by the increasing incidence of immune-related adverse events (irAEs). Although several factors and mechanisms have been proposed in the development of irAEs, there is still incomprehensive understanding of irAEs. Therefore, it is urgent to identify certain risk factors and biomarkers that predict the development of irAEs, as well as to understand the underlying mechanisms of these adverse events. Herein, we comprehensively summarize the state-of-the-art knowledge about clinical features and the related risk factors of irAEs. Particularly, we also discuss relevant mechanisms of irAEs and address the mechanism-based strategies, aiming to develop a tailored management approach for irAEs.

The Role of Tissue Biopsy in the Management of Immune Checkpoint Inhibitor Toxicity

Immune checkpoint inhibitors have revolutionized the treatment of cancer and are now omnipresent. However, immune-related adverse events can present with varying phenotypes and timing, which can pose diagnostic and therapeutic challenges for the treating oncologist as well as subspecialty consultants. Biopsies of affected organs may provide insight into biologic mechanisms as well as potentially guide management in certain circumstances.

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.

Flexible sigmoidoscopy may be sufficient for initial evaluation of suspected immunotherapy-mediated colitis: A cross-sectional study

BACKGROUND AND AIM

Immune checkpoint inhibitors (ICIs) have shown promise in treating a variety of cancers. Their increased use coincides with increased incidence of immunotherapy-mediated colitis (IMC), a common adverse effect. Optimal strategy for endoscopic evaluation of IMC (full colonoscopy or flexible sigmoidoscopy) is not well-defined.

METHODS

Retrospective review of all patients at City of Hope referred to gastroenterology for evaluation of IMC due to gastrointestinal symptoms was performed. Patients with an existing histologic diagnosis of IMC established at an outside hospital or a diagnosis of infectious or chronic colitis were excluded.

RESULTS

We identified 51 symptomatic patients on ICIs prompting evaluation for IMC with colonoscopy (47/51) or flexible sigmoidoscopy (4/51). All distal rectosigmoid biopsies during flexible sigmoidoscopy demonstrated histologic evidence of IMC. In full colonoscopy, IMC was either present in all segments of colon simultaneously (35/47) or absent from all segments (12/47). No isolated proximal colonic biopsies demonstrated IMC. Endoscopically normal mucosa demonstrated histologic evidence of IMC up to 68.6% of the time. Endoscopically abnormal right, transverse, and left colon had low sensitivity (35.3%, 34.3%, and 41.7%, respectively) and high specificity (100.0%, 100.0%, and 91.7%, respectively) for histological presence of IMC.

CONCLUSIONS

Distal colon biopsies in patients on ICI therapy with diarrhea and suspected IMC were sufficient for diagnosing IMC in our cohort. Further, we found histologic evidence of IMC in biopsies taken from normal-appearing mucosa in a number of patients, suggesting that a normal endoscopic appearance does not preclude the presence of IMC and biopsies should be taken from both normal and abnormal-appearing mucosa.

Systematic review: disease activity indices for immune checkpoint inhibitor-associated enterocolitis

BACKGROUND

Although there is interest in developing pharmacotherapies for the treatment of immune checkpoint inhibitor-associated enterocolitis (ICIC), there is currently no consensus on how to optimally measure disease activity in this condition.

AIMS

To identify all scoring indices used for the measurement of disease activity in ICIC, assess their operating properties, and explore their potential utility as outcome measures.

METHODS

We searched MEDLINE, EMBASE and the Cochrane Library from inception to November 2020 to identify studies that evaluated disease activity and severity in patients with ICI-associated enterocolitis. These scoring tools could be designed specifically for ICIC or adapted from other diseases, and assessed clinical, endoscopic, or histologic disease activity.

RESULTS

Sixty-four studies were included. The Common Terminology Criteria for Adverse Events is commonly used to describe symptoms, although has only been partially validated and was not designed as a disease activity index. Endoscopic and histologic indices used in inflammatory bowel disease have been adopted for ICIC including the Mayo Endoscopic Subscore, Ulcerative Colitis Endoscopic Index of Severity, Simple Endoscopic Score for Crohn's Disease, Nancy Histological Index, Robarts Histopathological Index, and Geboes Score, among others. None of these indices has been validated for use in ICIC, and all lacked content validity and responsiveness.

CONCLUSIONS

There are no validated clinical, endoscopic, or histologic outcomes to assess disease activity in ICIC. Development and validation of reliable and responsive outcome measures that can be used to measure disease activity will be paramount for both clinical practice and for the development of treatments.

Update on Immune Checkpoint Inhibitor Enterocolitis

PURPOSE OF REVIEW

Immune checkpoint inhibitor (ICI) therapy revolutionized the treatment of multiple solid and hematologic malignancies. Yet, with it came profound inflammatory toxicities that mimic autoimmune diseases, termed immune-related adverse events (irAEs). Prominent among these is gastrointestinal inflammation, including a spectrum of gastritis, enteritis, and colitis. Here we synthesize an approach to immune checkpoint related enterocolitis (irEC) - including diagnostics and therapeutics - underpinned by new insights into the mechanism behind these phenomena.

RECENT FINDINGS

This review presents updated insights on how to approach irEC, including novel approaches to selective immunosuppressive therapy, the role of fecal microbiota transplant, and the underlying cellular mechanisms of irEC. This review provides an update on irEC diagnosis and therapy, with considerations of new therapies and special patient populations. The field of gastrointestinal irAEs requires additional investigation, which will ultimately provide the tools required for patients to continue to receive life-saving ICI therapy.

Gastrointestinal Adverse Events Induced by Immune-Checkpoint Inhibitors

BACKGROUND

As immune-checkpoint inhibitors (ICI) are becoming standard therapies for malignant tumors, increasing attention has been paid to their associated immune-related adverse events (irAEs). The gastrointestinal tract is the major site of irAEs, and it has recently become evident that the large bowel is the most frequently affected region. The aim of this narrative review was to clarify the endoscopic and histopathologic findings of and treatments for ICI-induced colitis.

SUMMARY

Endoscopic findings of ICI-induced colitis include a reddish, edematous mucosa with increased mucous exudate, loss of normal vascularity, and a granular mucosa with or without mucosal breaks. Histopathologic findings of ICI-induced colitis are expansion of the lamina propria, intraepithelial infiltration of neutrophils, crypt architectural distortion, neutrophilic crypt abscess, and prominent apoptosis. The clinical, endoscopic, and histopathologic severity of ICI-induced colitis is diverse, but colonoscopy together with biopsy is necessary for diagnosis. While a certain proportion of patients with ICI-induced colitis have an intractable clinical course, management guidelines are based on retrospective analyses. Prospective studies are needed to assess the efficacy of various medications, including immunosuppressive regimens. Key Messages: Colonoscopy with biopsy is the gold standard for the diagnosis of ICI-induced colitis. Endoscopists should be aware of the clinical features and pathophysiology of ICI-induced colitis for prompt diagnosis and treatment planning.

Immune checkpoint inhibitor-mediated colitis in gastrointestinal malignancies and inflammatory bowel disease

Immune checkpoint inhibitors (ICI) have markedly changed the landscape of cancer therapy. By re-invigorating the immune system against tumors, ICI provide novel therapeutic options for a broad variety of malignancies, including many gastrointestinal (GI) cancers. However, these therapies can also induce autoimmune-like side effects in healthy tissue across the body. One of the most common of these side effects is ICI-mediated colitis and diarrhea (IMC). Here, we review the incidence and risk of IMC in ICI therapy, with a focus on what is known regarding IMC in patients with GI malignancies. We also discuss data available on the use of ICI and risk of IMC in patients with pre-existing inflammatory bowel disease, as these patients may have increased risk of IMC due to their underlying intestinal pathology.

Diagnosis and Management of Immune Checkpoint Inhibitor Colitis

Increased use of immune checkpoint inhibitors (ICIs) has created a rise in immune-related adverse events (irAEs), which may affect any system in the body. Gastrointestinal (GI) irAEs such as immune-mediated colitis are common, occurring in 35% to 50% of patients receiving ICIs. GI irAEs usually develop 6 to 8 weeks after ICI initiation and can involve any part of the GI system. Patients with immune-mediated colitis are categorized into 1 of 5 grades based on the National Cancer Institute's Common Terminology Criteria for Adverse Events, which also guide treatment decisions. An infectious cause for the diarrhea should be excluded in all patients. Patients with grade 1 symptoms are managed conservatively. Patients with grade 2 or higher symptoms should undergo a colonoscopy and are treated with systemic corticosteroids and, depending on their response, biologic therapy. The aim of this article is to review the diagnosis and management of patients with immune-mediated colitis, which should be identified early and addressed promptly to avoid detrimental outcomes.

Clinical outcomes of patients with corticosteroid refractory immune checkpoint inhibitor-induced enterocolitis treated with infliximab

INTRODUCTION

Immune checkpoint inhibitors (CPIs) have changed the treatment landscape for many cancers, but also cause severe inflammatory side effects including enterocolitis. CPI-induced enterocolitis is treated empirically with corticosteroids, and infliximab (IFX) is used in corticosteroid-refractory cases. However, robust outcome data for these patients are scarce.

METHODS

We conducted a multicenter (six cancer centers), cohort study of outcomes in patients treated with IFX for corticosteroid-refractory CPI-induced enterocolitis between 2007 and 2020. The primary outcome was corticosteroid-free clinical remission (CFCR) with Common Terminology Criteria for Adverse Events (CTCAE) grade 0 for diarrhea at 12 weeks after IFX initiation. We also assessed cancer outcomes at 1 year using RECIST V1.1 criteria.

RESULTS

127 patients (73 male; median age 59 years) were treated with IFX for corticosteroid-refractory CPI-induced enterocolitis. Ninety-six (75.6%) patients had diarrhea CTCAE grade >2 and 115 (90.6%) required hospitalization for colitis. CFCR was 41.2% at 12 weeks and 50.9% at 26 weeks. In multivariable logistic regression, IFX-resistant enterocolitis was associated with rectal bleeding (OR 0.19; 95% CI 0.04 to 0.80; p=0.03) and absence of colonic crypt abscesses (OR 2.16; 95% CI 1.13 to 8.05; p=0.03). Cancer non-progression was significantly more common in patients with IFX-resistant enterocolitis (64.4%) as compared with patients with IFX-responsive enterocolitis (37.5%; p=0.013).

CONCLUSION

This is the largest study to date reporting outcomes of IFX therapy in patients with corticosteroid-refractory CPI-induced enterocolitis. Using predefined robust endpoints, we have demonstrated that fewer than half of patients achieved CFCR. Our data also indicate that cancer outcomes may be better in patients developing prolonged and severe inflammatory side effects of CPI therapy.

Multi-detector computed tomography (MDCT)-based severity score as a prognostic tool in patients with suspected immune checkpoint inhibitor therapy associated colitis

OBJECTIVE

This study aimed to assess MDCT as a diagnostic and prognostic tool in patients with suspected immune checkpoint inhibitor (ICI)-related colitis.

MATERIALS AND METHODS

This retrospective cohort study included patients receiving ICIs at three hospitals between 2015 and 2019 who underwent both abdominopelvic MDCT and endoscopic biopsy to workup suspected ICI-related colitis. Two radiologists independently reviewed MDCT images for signs of colitis based on pre-defined features. Diagnostic performance of MDCT was calculated and categorical variables between treatment subgroups were compared. Logistic regression was used to develop proposed MDCT criteria for diagnosis and MDCT severity score based on a combination of MDCT features of colitis to predict the patient outcomes in ICI-related colitis.

RESULTS

A total of 118 MDCT scans from 108 patients were evaluated for suspected colitis, with 72 confirmed ICI-related colitis cases. Sensitivity, specificity, PPV, and NPV of MDCT for diagnosis of ICI-related colitis was 81% (58/72), 52 % (24/46), 73% (58/80), and 63% (24/38), respectively. Small bowel involvement was visualized in 25% of cases with ICI-related colitis (18/72). In melanoma patients presenting with diarrhea grade ≥ 2 (n = 40), MDCT had the best diagnostic performance for ICI-related colitis (specificity = 80% [8/10], PPV = 92% [23/25]). MDCT severity scores predicted intravenous steroid use (OR 10.3, p = 0.004), length of stay > 7 days (OR 9.0, p < 0.001), and endoscopic mucosal ulceration (OR 4.7, p = 0.02).

CONCLUSION

MDCT is a useful diagnostic and prognostic tool for evaluating patients with immune checkpoint inhibitor-related colitis. An MDCT-based severity score enables assessment of disease severity and predicts outcome.

KEY POINTS

• MDCT is useful for the diagnosis of colitis in patients receiving immune checkpoint inhibitor (ICI) therapy, and an MDCT-based severity score allows for prognostication of patient outcomes. • MDCT yielded moderate sensitivity (81%) for diagnosis of ICI-related colitis but limited specificity (52%). However, in symptomatic melanoma patients (grade 2-4 diarrhea) with a high pretest probability, MDCT proved useful for diagnosis with a high PPV (92%). • For ICI-related colitis, our proposed MDCT severity score has prognostic value in predicting intravenous steroid use, prolonged length of stay during inpatient admission (> 7 days), and endoscopic mucosal ulceration.

Histopathology of Gastrointestinal Immune-related Adverse Events: A Practical Review for the Practicing Pathologist

Immune checkpoint inhibitors target checkpoint proteins with the goal of reinvigorating the host immune system and thus restoring antitumor response. With the dramatic increase in the use of checkpoint inhibitors for cancer treatment, surgical pathologists have assumed a major role in predicting the therapeutic efficacy (score based on programmed cell death ligand 1 immunohistochemistry and mismatch repair protein loss) as well as diagnosing the complications associated with these medications. Immune-related adverse events (irAEs) manifest as histologic changes seen in both the upper and lower gastrointestinal tract, and when viewed in isolation, may be morphologically indistinguishable from a wide range of diseases including infections, celiac disease, and inflammatory bowel disease, among others. Evaluation of biopsies from both the upper and lower gastrointestinal tract can aid in the distinction of gastrointestinal irAEs from their mimics. In the liver, the histologic changes of hepatic irAEs overlap with de novo diseases associated with hepatitic and cholangitic patterns of injury. The diagnosis of irAEs requires communication and collaboration from the pathologist, oncologist, and gastroenterologist. This review provides a background framework and illustrates the histologic features and differential diagnosis of gastrointestinal and hepatic irAEs.

Checkpoint blockade toxicities: Insights into autoimmunity and treatment

Checkpoint blockade has transformed not only the way cancers are treated, but also highlighted the importance of mounting a proper immune response against tumors. Despite advances in the field of immunotherapy, many patients develop a range of inflammatory toxicities that limit the efficacy of these therapies. These toxicities range from barrier site injury, such as colitis, to endocrine organ dysfunction, such as diabetes. In order to properly treat patients with cancer and avoid checkpoint blockade induced toxicities, we must gain a deeper understanding of the underlying mechanisms generating these adverse events. Cytotoxic and tissue-resident T cells likely play an important role in mediating some toxicities, though high levels of cytokines and the generation of auto-antibodies in other toxicities demonstrates these mechanisms are not all shared. Certain risk factors for specific toxicities may be able to predict who might benefit most from alternative therapies given the risk-benefit associated with checkpoint blockade. As the targets of checkpoint inhibitors have important functions in the prevention of autoimmunity, insights into risk factors and causes of toxicities will further our knowledge of fundamental immunology and enable the development of novel therapeutics.

Predicting and Preventing Immune Checkpoint Inhibitor Toxicity: Targeting Cytokines

Cancer immunotherapies can successfully activate immune responses towards certain tumors. However, this can also result in the development of treatment-induced immune-related adverse events (irAEs) in multiple tissues. Growing evidence suggests that cytokine production in response to these therapeutics potentiates the development of irAEs and may have predictive value as biomarkers for irAE occurrence. In addition, therapeutic agents that inhibit cytokine activity can limit the severity of irAEs, and their use is being tested in the clinical setting. This review provides an in-depth analysis of strategies to uncouple the cytokine response, that precipitates irAEs following cancer immunotherapies, from the benefit gained in promoting antitumor immunity.

Understanding and treating the inflammatory adverse events of cancer immunotherapy

During the past decade, immunotherapies have made a major impact on the treatment of diverse types of cancer. Inflammatory toxicities are not only a major concern for Food and Drug Administration (FDA)-approved checkpoint blockade and chimeric antigen receptor (CAR) T cell therapies, but also limit the development and use of combination therapies. Fundamentally, these adverse events highlight the intricate balance of pro- and anti-inflammatory pathways that regulate protective immune responses. Here, we discuss the cellular and molecular mechanisms of inflammatory adverse events, current approaches to treatment, as well as opportunities for the design of immunotherapies that limit such inflammatory toxicities while preserving anti-tumor efficacy.

Clinicopathological characteristics and management of colitis with anti-PD1 immunotherapy alone or in combination with ipilimumab

Background

Colitis is one of the common immune-related adverse events that leads to morbidity and treatment discontinuation of immunotherapy. The clinical presentation, endoscopic and histopathological features and best management of this toxicity are not well defined.

Patients and methods

Patients with metastatic melanoma who received immunotherapy (programmed cell death protein 1 (PD1) antibodies, alone or in combination with a cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) antibody (PD1 +CTLA-4)) and who developed clinically significant colitis (requiring systemic corticosteroids) were identified retrospectively from two academic centers. Clinical data were collected for all patients; endoscopic and histopathological data were examined in a subset.

Results

From May 2013 to May 2019, 118/1507 (7.8%) patients developed significant colitis; 80/553 (14.5%) after PD1+CTLA-4, 35/1000 (3.5%) PD1 alone, and three patients after Ipilimumab (IPI) alone. Combination therapy-induced colitis was more frequent (14.5% vs 3.5% in PD1 alone, p=<0.0001), had an earlier onset (6.3 weeks vs 25.7 weeks, p=<0.001), was more severe (grade 3/4 69% vs 31%, p=<0.001), and are more likely to require higher doses of steroids (91% vs 74%, p=0.01) than PD1 colitis. Among all patients treated with steroids (N=114), 54 (47%) responded and required no further therapy (steroid sensitive), 47 patients (41%) responded to infliximab (infliximab sensitive), and 13 (11%) were infliximab refractory and needed further immunosuppressive drugs. Infliximab-refractory patients all had onset within 4 weeks of immunotherapy commencement and were more likely to have an underlying autoimmune disease, have higher grade colitis, and require longer immunosuppression, yet had similar response and survival than other patients with colitis. Of 43 (37%) patients re-resumed treatment with PD1 monotherapy after colitis resolution, 16 (37%) of whom developed recurrent colitis. Endoscopic and histopathologic data were available for 64 patients. Most had left-sided colitis, with an increase in chronic inflammatory cells and neutrophils within the lamina propria, an increase in neutrophils in the surface epithelium, without increased lymphocytes or increased eosinophils. Infliximab-refractory colitis had a trend towards more confluent pancolitis with edema, erythema, ulceration, and absent vascularity with neutrophilic infiltration and erosion.

Conclusion

Clinically significant colitis varies in presentation, response to immunosuppression, and endoscopic/histologic features depending on the immunotherapy type. Infliximab-refractory colitis occurs early, is often high grade, and has adverse endoscopic and histopathologic features

Diagnostic utility of CT for suspected immune checkpoint inhibitor enterocolitis

BACKGROUND AND AIMS

Immune checkpoint inhibitor (ICI) enterocolitis is a common immune-related adverse event and can be fatal, especially when not diagnosed and treated promptly. The current gold standard for diagnosis is endoscopy with biopsy, but CT scan is a possible alternative. The primary objective of this study is to identify the diagnostic performance of CT in the evaluation of ICI enterocolitis.

METHODS

With institutional review board approval, we conducted a retrospective cohort study of patients who received ICI therapy between 2015 and 2019 across a healthcare system. Patients were included if they underwent both abdominal CT and endoscopy with biopsy within 3 days. The radiological and pathological diagnoses, as well as clinical characteristics, were extracted from the electronic medical record. We calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of CT for diagnosing ICI enterocolitis when compared with tissue diagnosis.

RESULTS

Of the 4474 patients screened, 138 met inclusion criteria. Most common tumor types were melanoma (37%) and lung cancer (19%). Seventy-four per cent were treated with antiprogrammed cell death (PD-1)/PD-L1 therapy. Thirty-nine per cent had signs of enterocolitis on CT scan and 58% had biopsy-proven ICI enterocolitis. Sensitivity and specificity of CT were 50% and 74%, respectively. PPV was 73% and NPV was 52%. Of those with confirmed ICI enterocolitis, 70% had grade 3 or higher symptoms, 91% received steroids and 40% received infliximab.

CONCLUSION

The performance of CT scan for diagnosis of ICI enterocolitis is moderate to poor and does not replace endoscopy with biopsy.

Multinational Association of Supportive Care in Cancer (MASCC) 2020 clinical practice recommendations for the management of severe gastrointestinal and hepatic toxicities from checkpoint inhibitors

Immune-related adverse events (IrAEs) affecting the gastrointestinal (GI) tract and liver are among the most frequent and most severe inflammatory toxicities from contemporary immunotherapy. Inflammation of the colon and or small intestines (entero)colitis is the single most common GI IrAE and is an important cause of delay of discontinuation of immunotherapy. The severity of these GI IrAEs can range from manageable with symptomatic treatment alone to life-threatening complications, including perforation and liver failure. The frequency and severity of GI IrAEs is dependent on the specific immunotherapy given, with cytotoxic T lymphocyte antigen (CTLA)-4 blockade more likely to induce severe GI IrAEs than blockade of either programmed cell death protein 1 (PD-1) or PD-1 ligand (PD-L1), and combination therapy showing the highest rate of GI IrAEs, particularly in the liver. To date, we have minimal prospective data on the appropriate diagnosis and management of GI IrAEs, and recommendations are based largely on retrospective data and expert opinion. Although clinical diagnoses of GI IrAEs are common, biopsy is the gold standard for diagnosis of both immunotherapy-induced enterocolitis and hepatitis and can play an important role in excluding competing, though less common, diagnoses and ensuring optimal management. GI IrAEs typically respond to high-dose corticosteroids, though a significant fraction of patients requires secondary immune suppression. For colitis, both TNF-α blockade with infliximab and integrin inhibition with vedolizumab have proved highly effective in corticosteroid-refractory cases. Detailed guidelines have been published for the management of low-grade GI IrAEs. In the setting of more severe toxicities, involvement of a GI specialist is generally recommended. The purpose of this review is to survey the available literature and provide management recommendations focused on the GI specialist.