Immune modulator-induced changes in the gastrointestinal tract

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.

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.

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.

Histopathologic Features of Immune-related Adverse Events in the Gastrointestinal Tract: A Case of Severe Acute Respiratory Syndrome Coronavirus 2 and Cytomegalovirus Infection in a Patient with Lung Squamous Cell Carcinoma Receiving Immune Checkpoint Inhibitors

In this article, we report the case of a patient with unresectable stage III squamous cell lung carcinoma who developed immune-related adverse events in the gastrointestinal tract following the administration of immune checkpoint inhibitors. The patient developed severe acute respiratory syndrome coronavirus 2 pneumonia and cytomegalovirus gastritis during immunosuppressive therapy for an immune-related adverse event. Cytomegalovirus infection was managed with the administration of ganciclovir.

Endoscopic and histopathologic features of Anti‐PD‐1‐related collagenous colitis

Objectives

Cancer patients treated with immune checkpoint inhibitors occasionally show persistent diarrhea accompanied by endoscopic features of ulcerative colitis. The endoscopic mucosal inflammation may appear mild in some patients compared to the clinical severity, which can make choosing a treatment challenging. In this study, we evaluated the factors that support the continuation of chemotherapy by assessing the endoscopic and histopathological characteristics of patients who experienced diarrhea after immune checkpoint inhibitor administration.

Methods

This study included eight patients who were diagnosed with collagenous colitis based on pathological assessments. We retrospectively investigated these patients’ backgrounds, laboratory data, and computed tomography images that were extracted from their medical records. We also summarized their endoscopic and pathologic findings.

Results

All eight patients were being treated with anti‐programmed cell death‐1/programmed cell death‐ligand 1 therapeutic agents and had a recent history of oral proton pump inhibitor therapy. The anti‐programmed cell death‐1‐related collagenous colitis in these cases was characterized by endoscopically mild mucosal inflammation, high fecal calprotectin levels, and a lower frequency of intestinal wall thickening on computed tomography. Histological assessments showed CD8⁺ lymphocytes predominantly infiltrating the lamina propria and crypts of the colonic mucosa. Suspending the proton pump inhibitor therapy relieved the patients’ symptoms and allowed the continuation of the anti‐programmed cell death‐1/programmed cell death‐ligand 1 therapy.

Conclusions

Anti‐programmed cell death‐1‐related collagenous colitis is reversible; appropriate diagnosis of adverse events is crucial for the continuation of immune checkpoint inhibitor therapy.

Histological Features of Celiac-Disease-like Conditions Related to Immune Checkpoint Inhibitors Therapy: A Signal to Keep in Mind for Pathologists

Immune checkpoint inhibitors (ICIs) targeting cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), programmed cell death protein (PD-1), and its ligand PDL-1, are finding increasing application in the treatment of malignant neoplasms. The widespread clinical use of these drugs, however, resulted in the discovery of side effects. The occurrence of celiac disease (CD) after ICIs therapy has been reported in the literature, but its incidence remains unknown and the role of ICIs in its onset is not yet clear. In this review, we examine the published data on this topic in order to better understand and define this entity from a histological point of view. We performed an electronic literature search to identify original reports in which CD or pathological CD-like conditions were documented histologically in patients treated with ICIs. We identified ten papers. A total of twenty-five patients were included in these publications, eleven of them receiving a serologic and histological diagnosis of CD, and four a histological diagnosis of CD-like conditions, in which pathogenesis appears to be multifactorial. ICIs can cause a CD-like enteropathy and biopsies with clinical integration are crucial to diagnose this condition. CD rarely has been observed during treatment with ICIs and its morphological aspects are similar to ICIs-CD enteropathy. Moreover, the onset of ICIs-CD may have a distinct immune mechanism compared to classical CD. Thus, the pathologists must make a histological diagnosis of CD with caution and only in adequate clinical and serological context.

Immunotherapy-Mediated Luminal Gastrointestinal Toxicities

The advent of immune checkpoint blockade and its application in the management of advanced malignancies has revolutionized cancer therapies, outcomes, and survival. As beneficial as these class of drugs have been proven to be, their use is not devoid of complications, viz., immune-related adverse events (irAEs). The gastrointestinal (GI) tract is the second most frequently affected organ system, and toxicities may vary in severity from mild disease to aggressive life-threatening clinical presentations. Timely diagnosis that incorporates clinical, biochemical, imaging, endoscopic, and histologic evaluation is imperative for efficacious management of this disease process to ensure good outcomes. Management varies depending on severity and can comprise supportive care in milder disease patterns as well as vigorous immunosuppression in aggressive cases.

Immune Checkpoint Inhibitor-Associated Colitis: From Mechanism to Management

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

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

AIMS

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

METHODS AND RESULTS

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

CONCLUSIONS

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

[An unusual digestive complication under anti-PD-1 (pembrolizumab)]

The most commonly reported pattern of anti-PD-1 induced colitis is an active colitis characterized by neutrophilic inflammation and prominent apoptosis. On the other hand, reports of collagenous colitis (which is a microscopic colitis) are exceptional. In this report, we describe an unusual case of anti-PD1-associated collagenous colitis in a 76-year-old man, treated with pembrolizumab for a stage IV cutaneous melanoma. Fourteen months after the start of pembrolizumab, the patient developed a grade 3 diarrhea (up to 9 stools per day) associated with profound hypokalemia. No bacterial, viral or parasitological infectious agents were found from stool analysis. The rectosigmoidoscopy showed colonic diffuse congestion with no ulceration. Systematic biopsies were performed during endoscopy. Histologically, the fragments analyzed revealed a moderately thickened subepithelial collagen layer (20-30μm thick) associated with a mild mixed inflammatory infiltrate within the lamina propria. There were no granuloma lesions, ulcerations or viral inclusion bodies. The patient was initially successfully treated with corticosteroids (prednisone) and temporary interruption of pembrolizumab. However, during corticosteroids tapering, a relapse was observed. The treatment was switched to budesonide, leading to a complete and definitive resolution of diarrhea. To date, budesonide has been stopped and pembrolizumab has not been restarted. Currently, there is a bone progression treated by radiotherapy alone. In case of a more important progression, a systemic treatment will be secondarily discussed.

Gastrointestinal Tract Adverse Events

Immune checkpoint inhibitors (ICIs) have shown significant benefit in cancer patients. Their success, however, is associated with immune-related adverse events (irAEs), which commonly affect the gastrointestinal tract, resulting in diarrhea and colitis. IrAEs range from mild self-limiting to severe life-threatening diseases and potentially limit the use of these medications. Diagnosis of ICI-induced enterocolitis is based on clinical symptoms, physical examination, stool tests, endoscopic and histologic evaluation, and/or imaging. Current management strategy is mainly anti-diarrheal agents for mild symptoms and immunosuppressants (e.g., corticosteroids, and infliximab or vedolizumab) for more severe diseases.

Metabolic consequences of immune checkpoint inhibitors: A new challenge in clinical practice

Treatment of oncologic patients has progressed greatly the last few years with the development of immune checkpoint inhibitors (ICPIs). These drugs are associated with the immune system and, thus, may cause side effects of immune origin, the so called immune related adverse events (irAEs). Immune related AEs may actually affect all organs and systems and frequently resemble clinical entities commonly encountered in clinical practice. As ICPIs have improved both quality of life and life expectancy, clinicians of various specialties may need to deal with irAEs in their everyday practice. Therefore, they should be able to recognize them timely and treat them accordingly. Herein, we review the pathophysiology, clinical manifestations and treatment of irAEs.

Management Considerations for Immune Checkpoint Inhibitor-Induced Enterocolitis Based on Management of Inflammatory Bowel Disease

BACKGROUND

Immune checkpoint inhibitor therapy has significantly improved the outcomes of various advanced malignancies that were deemed unruly prior to its invention. Immune-mediated diarrhea and enterocolitis are among the most frequently encountered adverse events of immune checkpoint inhibitor therapy. Given the increasing use of these therapies in the treatment of an ever-growing number of malignancies, providing appropriate treatment for such adverse effects has become crucial.

METHODS

In this review, we summarize the current body of evidence concerning the management of immune-mediated diarrhea and enterocolitis. Additionally, management of immune-mediated diarrhea and enterocolitis is likened to that of inflammatory bowel disease, given the resemblance between both entities in pathogenesis and clinical features. Reviewing the literature raised several points regarding this devastating toxicity that still need further investigation by future efforts.

RESULTS

Endoscopic and histologic evaluation is pivotal in the assessment of immune-mediated diarrhea and enterocolitis and provides vital information regarding the severity of the disease to guide treatment. Corticosteroids are the main therapy for immune-mediated diarrhea and enterocolitis, with infliximab and vedolizumab as second-line agents. Recently, fecal microbiota transplantation has emerged as a treatment option for immune-mediated diarrhea and enterocolitis that is refractory to corticosteroids. Restarting immune checkpoint inhibitor therapy after resolution of immune-mediated diarrhea and enterocolitis carries a risk of recurrence that is mostly controllable with current immune-suppressive treatment.

CONCLUSIONS

Lastly, we propose a management algorithm for immune-mediated diarrhea and enterocolitis. Prospective research, preferably as collaborative efforts from oncology and gastroenterology specialists, is needed to refine the management of immune-mediated diarrhea and enterocolitis.

Checkpoint Inhibitor-Induced Colitis

Immune checkpoint inhibitors have revolutionized treatment and overall survival for several different types of cancer. Antibodies to cytotoxic T-lymphocyte-associated protein 4 and to programmed cell death protein 1 and its ligand enhance cytotoxic T-cell survival, thus augmenting antitumor action and consequently inducing immune-related adverse events, of which the most relevant is diarrhea and colitis. This review compiles recent data on pathophysiology, clinical manifestations, and treatment of immune-mediated colitis (IMC). The pathogenesis of IMC is not completely understood, but recent studies have focused on the role of regulatory T cells and interactions with the gut microbiome. While sharing similarities with inflammatory bowel disease, IMC is considered a distinct form of colitis with acute onset and rapid progression leading to potential complications including bowel perforation and death. Prompt recognition and management of IMC is imperative for optimal outcomes. Although prospective clinical trials are lacking to guide therapy, recent guidelines recommend early endoscopic evaluation to establish the diagnosis and prompt initiation of corticosteroids. Response to first-line therapy should be assessed early to determine the need of escalation to biologic agents. With treatment, most patients will experience full resolution of symptoms, and subsequent rechallenge with anti-programmed cell death protein 1 or anti-programmed death-ligand 1 inhibitors can be considered.

Immune checkpoint inhibitor-induced diarrhea/colitis: Endoscopic and pathologic findings

The indications of immune checkpoint inhibitors (ICPIs) for cancer treatment have rapidly expanded, and their use is increasing in clinical settings worldwide. Despite the considerable clinical benefits of ICPIs, frequent immune-related adverse events (irAEs) have become nonnegligible concerns. Among irAEs, ICPI-induced colitis/diarrhea is frequent and recognized not only by oncologists but also by gastroenterologists or endoscopists. The endoscopic findings show similarity to those of inflammatory bowel disease to a certain extent, particularly ulcerative colitis, but do not seem to be identical. The pathological findings of ICPI-induced colitis may vary among drug classes. They show acute or chronic inflammation, but it may depend on the time of colitis suggested by colonoscopy, including biopsy or treatment intervention. In the case of chronic inflammation determined by biopsy, the endoscopy findings may overlap with those of inflammatory bowel disease. Here, we provide a comprehensive review of ICPI-induced colitis based on clinical, endoscopic and pathologic findings.

Mycophenolate mofetil alongside high-dose corticosteroids: optimizing the management of combination immune checkpoint inhibitor-induced colitis

Immune checkpoint inhibitor (IO) induced colitis is primarily managed with corticosteroids. Most patients have a rapid resolution of symptoms and do not require additional immunosuppressants. Many patients, however, require prolonged corticosteroid courses to maintain control of toxicity. Mycophenolate mofetil (MMF) is the prodrug of mycophenolic acid; which in turn directly inhibits activated T and B lymphocytes. MMF, in addition to corticosteroids, may enable reduction of corticosteroids without precipitating resurgence of colitis. Metastatic melanoma patients between 1 January 2017 and 31 December 2017 with combination IO-induced colitis were managed with a novel treatment algorithm: upfront oral enteric-coated MMF alongside high-dose corticosteroids. Outcome measures included incidence of colitis flare, time to grade 1 colitis, time to patient-reported normal bowel habit and overall cumulative corticosteroid exposure. Thirteen patients developed high-grade combination IO-induced colitis; 11 were managed with the combination of high-dose corticosteroid and MMF. Median patient age was 59 (range: 28-73) years. Four (36%) developed flare of colitis; flares occurred at a median of 11 (interquartile range: 4.5-16.75) days. All colitis flares responded fully to infliximab (5 mg/kg). The remaining seven patients did not develop colitis flare during corticosteroid wean. All patients were successfully weaned from corticosteroids and none had a resurgence of colitis at 8 weeks following discontinuation of MMF. Concomitant enteric-coated MMF alongside high-dose corticosteroids may hasten the improvement of high-grade colitis to normal bowel habit and reduce the incidence of colitis flare.

Upper gastrointestinal symptoms and associated endoscopic and histological features in patients receiving immune checkpoint inhibitors

Background: Immune checkpoint inhibitors (ICIs) have demonstrated effectiveness in treating many malignancies. Gastrointestinal (GI) adverse events are commonly reported; however, few reports describe upper GI tract toxic effects. We aimed to describe clinical features of upper GI injury related to ICI. Methods: We studied consecutive patients who received ICIs between April 2011 and March 2018 and developed upper GI symptoms requiring esophagogastroduodenoscopy (EGD). Results: Sixty patients developed upper GI symptoms between ICI initiation and 6 months after the last infusion. Among patients who had both EGD and colonoscopy (n = 38), 21 had endoscopic evidence of inflammation involving both the upper and lower GI tract. Overall, histological signs of inflammation of the stomach were evident in 83% of patients, but inflammation of the duodenum in 38%. Total of 42 patients had other risk factors of gastritis, i.e., chemotherapy, radiotherapy, and non-steroidal anti-inflammatory drugs. Only isolated gastric inflammation was seen on endoscopy in patients without these risk factors. The rates of ulceration were similar in the cohorts with and without other risk factors for gastritis. Isolated upper GI inflammation was related to anti-PD-1/L1 in 47% of patients. Immunosuppressive therapy in our cohort with upper GI toxicity consisted of steroids (42%) and infliximab or vedolizumab (23%). Most isolated upper GI symptoms were treated with proton pump inhibitors (65%) or H₂ blockers (35%). Conclusion: We observed a correlation between ICI use and onset of upper GI inflammation even when other risk factors were excluded. Gastric involvement was evident more often than duodenal involvement on endoscopic and histological level.

Enterocolitis due to immune checkpoint inhibitors: a systematic review

Immune checkpoint inhibitors targeting cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) and programmed death-1 (PD-1)/ligand are increasingly used to treat several types of cancer. These drugs enhance antitumour T-cell activity and therefore induce immune-related adverse effects (irAE), of which gastrointestinal (GI) irAE are among the most frequent and severe. This systematic literature review summarises the clinical manifestations, management and pathophysiology of GI irAE due to immune checkpoint inhibitors. GI irAE induced by anti-CTLA-4 are frequent, potentially severe and resemble IBD, whereas those induced by PD-1 blockade seem to be less frequent and clinically more diverse. Baseline symbiotic gut microbiota is associated with an enhanced antitumour response to immune checkpoint inhibitors and an increased susceptibility to developing enterocolitis, in patients treated with anti-CTLA-4. These findings open new perspectives for possible manipulation of the gut microbiota in order to better identify responders to immune checkpoint inhibitors and to increase their efficacy and safety.

Immune checkpoint inhibitor-induced gastrointestinal and hepatic injury: pathologists' perspective

Immune checkpoint inhibitors (CPIs) are a relatively new class of 'miracle' dugs that have revolutionised the treatment and prognosis of some advanced-stage malignancies, and have increased the survival rates significantly. This class of drugs includes cytotoxic T lymphocyte antigen-4 inhibitors such as ipilimumab; programmed cell death protein-1 inhibitors such as nivolumab, pembrolizumab and avelumab; and programmed cell death protein ligand-1 inhibitors such as atezolizumab. These drugs stimulate the immune system by blocking the coinhibitory receptors on the T cells and lead to antitumoural response. However, a flip side of these novel drugs is immune-related adverse events (irAEs), secondary to immune-mediated process due to disrupted self-tolerance. The irAEs in the gastrointestinal (GI) tract/liver may result in diarrhoea, colitis or hepatitis. An accurate diagnosis of CPI-induced colitis and/or hepatitis is essential for optimal patient management. As we anticipate greater use of these drugs in the future given the significant clinical response, pathologists need to be aware of the spectrum of histological findings that may be encountered in GI and/or liver biopsies received from these patients, as well as differentiate them from its histopathological mimics. This present review discusses the clinical features, detailed histopathological features, management and the differential diagnosis of the luminal GI and hepatic irAEs that may be encountered secondary to CPI therapy.

Immune checkpoint inhibitor colitis: the flip side of the wonder drugs

Immune checkpoint inhibitors block the co-inhibitory receptors on T cells to activate their cytotoxic immune function and are rapidly being explored for the treatment of various advanced-stage malignancies. These novel drugs have already significantly increased survival rates. The first available immune checkpoint inhibitors were cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors (such as ipilimumab), followed by programmed cell death protein 1 (PD-1) and programmed cell death protein ligand 1 (PD-L1) inhibitors (such as pembrolizumab and nivolumab). Anti-PD-1 and anti-PD-L1 therapies have demonstrated better efficacy and tolerability and less severe adverse effects compared to anti-CTLA-4 agents. Idelalisib, a PI3Kδ isoform inhibitor, is another immunotherapeutic agent that is often classified separately and is currently used in treatment of chronic lymphocytic leukemia and non-Hodgkin lymphomas. Despite successful therapeutic responses, immune-related adverse events have been reported with the use of these agents. The gastrointestinal side effects, particularly diarrhea, are among the most commonly reported symptoms. The histologic features of immune checkpoint inhibitor-associated colitis show a spectrum of patterns of injury among various drug classes. There is significant overlap between immune checkpoint inhibitor-associated colitis and other colitides, making the differential diagnosis difficult-especially in the absence of clinical history. The histopathology data on immune checkpoint inhibitor-associated colitis are limited. Here we review clinical features as well as various histologic patterns of colitis associated with these groups of medications.