Critical Role of Innate Immunity to Flagellin in the Absence of Adaptive Immunity.

BACKGROUND: Bacterial flagellin is a major target of innate and adaptive immunity, both of which can promote and/or compensate for deficiencies in each other's function. METHODS: To investigate the role of innate immune detection of flagellin irrespective of adaptive immunity, we examined the consequences of loss of Toll-like receptor 5 (T5) and/or Nod-like receptor 4 (N4) upon a Rag1-deficient background. RESULTS: Mice lacking Toll-like receptor 5 and Rag1 (T5/Rag-DKO) exhibited frequent lethal Pasteurellaceae-containing abscesses that prevented breeding of these mice. Mice lacking Toll-like receptor 5, Nod-like receptor 4, and Rag1 (T5/N4/Rag-TKO) also resulted in sporadic lethal abdominal abscesses caused by similar Pasteurellaceae. In the absence of such infections, relative to Rag1-KO, T5/N4/Rag-TKO mice exhibited microbiota encroachment, low-grade inflammation, microbiota dysbiosis, and, moreover were highly prone to Citrobacter infection and developed severe colitis when adoptively transferred with colitogenic T cells. Relative proneness of T5/N4/Rag-TKO mice to T-cell colitis was ablated by antibiotics while fecal microbiota transplant from T5/N4/Rag-TKO mice to wild-type mice transferred proneness to Citrobacter infection, indicating that dysbiosis in T5/N4/Rag-TKO mice contributed to these phenotypes. CONCLUSIONS: These results demonstrate a critical role for innate immune detection of flagellin, especially in the intestinal tract and particularly in hosts deficient in adaptive immunity.

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

PURPOSE: Nivolumab, a monoclonal antibody-targeting programmed cell death protein-1, is being increasingly used for the treatment of some advanced neoplasms. Several of its adverse effects are a result of the upregulation of T cells, with colitis as one of the most severe, and a challenging differential diagnosis with ulcerative colitis. However, few real-life clinical practice cases have been reported beyond trials. Our aim was to report a series of new cases, reviewing previously communicated endoscopic-proven nivolumab-induced colitis. METHOD: All patients treated with nivolumab in three university centers were identified and those who developed immune-mediated colitis (defined as the presence of diarrhea and evidence of colitis demonstrated by colonoscopy) were described. Additionally, a review of case reports of nivolumab-induced colitis reported in the literature up to March 2018 was performed. RESULTS: Six new cases of nivolumab-induced colitis and 13 previously reported cases out of randomized clinical trials are described. Colonoscopy showed a mucosal pattern mimicking ulcerative colitis in a large proportion of patients. Clostridium difficile superinfection was observed in two out of 19 cases. All but three patients definitively discontinued nivolumab therapy. Most patients were initially managed with oral or intravenous corticosteroids, but five of them required rescue therapy with infliximab. CONCLUSIONS: Nivolumab-induced colitis may mimic ulcerative colitis. Steroid therapy (oral or intravenously) is often efficient, but one-fourth of patients need rescue therapy with anti-TNF. Intestinal superinfection with Clostridium difficile or cytomegalovirus should be ruled out before starting immunosuppressive therapy.

Practice Changes in Checkpoint Inhibitor-Induced Immune-Related Adverse Event Management at a Tertiary Care Center.

Understanding of immune-related adverse events (irAEs) has evolved rapidly, and management guidelines are continually updated. We explored temporal changes in checkpoint inhibitor-induced irAE management at a tertiary cancer care center to identify areas for improvement. We conducted a single-center retrospective study of patients who developed a gastrointestinal, pulmonary, renal, or cardiac irAE between July and 1 October in 2019 or 2021. We collected patient demographic and clinical information up to 1 year after toxicity. Endoscopic evaluation and specialty follow-up after discharge for patients with gastrointestinal irAEs declined between the 2019 and 2021 periods. Symptom duration and steroid taper attempts also declined. For pulmonary irAEs, rates of specialty consultation, hospital admission and readmission, and mortality improved in 2021 compared with 2019. Follow-up rates after hospital discharge were consistently low (<50%) in both periods. For cardiac irAEs, consultation with a cardiologist was frequent and prompt in both periods. Outpatient treatment and earlier specialty consultation improved outcomes with gastrointestinal irAEs. Our study exploring irAE practice changes over time identified areas to improve management; specifically, timely specialty consultation was associated with better outcomes for gastrointestinal irAEs. These findings can help improve the quality of management algorithms at our institution and may inform policies in other institutions.

Fulminant immune-related colitis after dual checkpoint inhibitor therapy: case report.

Aim: Immune-related (IR) colitis is a potentially life-threatening complication of checkpoint inhibitors. Its presentation often includes diarrhea, abdominal pain and rectal bleeding and the median time to onset is 6-10 weeks post initiation of immunotherapy.Case study: We report an unusual case of fulminant IR-colitis beginning 3 days after the first dose of dual checkpoint blockade. IR-colitis was refractory to high-dose corticosteroids and was further complicated by sigmoid diverticulum perforation.Conclusion: Early-onset IR-colitis can occur, particularly in the context of combined anti-PD1 and anti-CTLA4 blockade, and clinicians should maintain a high-index of suspicion even when timing of symptom onset is atypical. Further research is needed to elucidate risk factors for early-onset IR-colitis.

We report an unusual case of immune-related (IR)-colitis that occurred just 3 days after receiving treatment for liver cancer with a class of drug called immunotherapy. Immunotherapy works by enabling our own immune system to attack cancer cells that should not be present in our body. One unwanted side effect of this therapy is that our immune system can attack normal tissue and organs. IR colitis is when immunotherapy leads the immune system to attack the large intestine, and often presents with abdominal pain, diarrhea and blood in the stool. This side effect typically occurs 6-10 weeks following start of immunotherapy. This case is unusual because of the very early onset of IR colitis. The patient reported herein had a severe case of IR colitis that required the surgical team to emergently remove part of his large intestine. This case demonstrates that IR colitis can happen significantly earlier than the typical time course, highlighting the need for clinicians and patients alike to maintain a high index of suspicion for this potentially life-threatening toxicity. Future studies should aim to identify potential risk factors for early-onset IR colitis.

Outcomes of Budesonide as a Treatment Option for Immune Checkpoint Inhibitor-Related Colitis in Patients with Cancer.

BACKGROUND: Current treatment guidelines for moderate to severe colitis (IMC) secondary to immune checkpoint inhibitors (ICI) recommend systemic corticosteroids as the primary therapy in conjunction with biologics, namely infliximab and/or vedolizumab. We aimed to explore the efficacy and safety of oral budesonide in the treatment of IMC. METHODS: We performed a retrospective analysis at MD Anderson Cancer Center of adult cancer patients with a confirmed (based on clinical, radiographic and laboratory assessment) diagnosis of IMC between 1 January 2015 and 31 November 2022, treated with budesonide. Data collection included demographics, oncologic history, IMC-related information and outcomes up to 6 months after the last dose of ICI. RESULTS: Our sample (n = 69) comprised primarily of Caucasian (76.8%) females (55.1%). The majority of patients received combination therapy with anti-PD-1/L1 and anti-CTLA-4 (49.3%), and the most common malignancy treated was melanoma (37.6%). The median grade of diarrhea was 3 and of colitis was 2. Of the 50 patients who underwent endoscopic evaluation, a majority had non-ulcerative inflammation (64%) and active colitis on histology (78%). Budesonide was used as primary treatment at onset of IMC in 56.5% patients, as well as a bridging therapy from systemic corticosteroids in 33.3%. Less than half of the patients (44.9%) required additional therapies such as biologics or fecal microbiota transplant. Additionally, 75.3% of patients achieved full remission of IMC and 24.6% had a recurrence of IMC. ICI was resumed in 31.9% of patients and 17.4% received other forms of cancer therapies. CONCLUSIONS: Budesonide may be an effective strategy to treat and prevent the recurrence of IMC. The remission rates observed in our analysis with budesonide alone are comparable to systemic corticosteroids. Patients that require an extended duration of steroid exposure and those with moderate to severe colitis may benefit from budesonide given its lower risk of infection and complications. Furthermore, we observe that budesonide may serve as a successful bridge from systemic corticosteroids with subsequent biologic treatment. Larger prospective studies are necessary to determine the role of budesonide as well as its safety profile.

Mirroring UC care pathways in refractory immune checkpoint inhibitor (ICI)-mediated colitis: distinct features and common pathways.

Immune checkpoint inhibitors (ICI) have transformed the management of cancer, producing durable responses in a subset of treated patients across multiple malignancies. Immune-mediated diarrhea and colitis (imDC) occurs in up to 20% of ICI-treated patients. The risk of ICI imDC is dependent upon the agent and is commoner with anti-CTLA-4 compared to anti-PD-1 ICIs. Generally, imDC is treated with steroids and agents targeting TNFα or α4ß7 integrin. However, the management of steroids and/or biologic refractory imDC is unclear. We present a case of imDC in a 68-year-old female who failed to respond clinically, biochemically and immunohistochemically to corticosteroids, infliximab and vedolizumab. A trial of tofacitinib, a pan-JAK inhibitor, led to rapid clinical, biochemical and immunohistochemical control of imDC. ICIs result in a striking accumulation of cytotoxic and proliferative CD8 + T cells within tumor. However, the cellular and molecular mechanisms underlying imDC remain unclear. Herein, we observed significant T cell enrichment; and the successful treatment with tofacitinib highlights the potential of multiple convergent inflammatory pathways in imDC and inflammatory colitis.

Characteristics and usefulness of transabdominal ultrasonography in immune-mediated colitis.

BACKGROUND/AIMS: The usefulness of ultrasonography (US) in diseases of the gastrointestinal tract has been reported recently. This prospective study aimed to determine the features of US findings in immune-mediated colitis (IMC), an adverse event induced by immune checkpoint inhibitor, and examine the correlation between US findings, colonoscopy (CS) findings, and severity of colitis. METHODS: We studied patients examined using CS and US upon suspicion of IMC in Hokkaido University Hospital between April 2018 and February 2021. Endoscopic findings of IMC were assessed using the Ulcerative Colitis Endoscopic Index of Severity (UCEIS). The severity of US findings in IMC was evaluated using US grade, which is the ultrasonographic grading scale in ulcerative colitis. Bowel wall thickness and the intensity of the color Doppler signal were also analyzed. Severity of colitis was evaluated using Common Terminology Criteria for Adverse Events (CTCAE) grade version 5. RESULTS: Fourteen patients with IMC were enrolled. The US findings were bowel wall thickening, loss of stratification, ulceration and increased blood flow signal. The US grade was moderately correlated with the UCEIS (r=0.687, p=0.009) and CTCAE grade (r=0.628, p=0.035). Bowel wall thickness and UCEIS (r=0.628, p=0.020), as well as color Doppler signal grade and CTCAE grade (r=0.724, p=0.008), were significantly correlated. CONCLUSIONS: US findings in IMC were mainly similar to those of ulcerative colitis, but there were some findings that were characteristic only of IMC. Significant correlation was found between US findings, CS findings, and severity of colitis. Hence, US could be useful for the evaluation of IMC.

Nivolumab-Induced Colitis in a Patient With Esophageal Adenocarcinoma: A Case Report.

Nivolumab is an immune checkpoint inhibitor used in the treatment of several types of cancer. Among the adverse effects of this drug, immune-mediated colitis (IMC) has been described. However, in contrast to other checkpoint inhibitors, such as ipilimumab, drug-induced colitis due to nivolumab is not commonly reported. We report the case of a 59-year-old male who had undergone surgical resection for gastroesophageal junction adenocarcinoma, had been on nivolumab during the past five months, and presented with worsening diarrhea. Colonoscopy demonstrated local edema and mild colitis in a region of the colonic mucosa located 30 cm distal to the ileocecal valve. Biopsies revealed acute moderate colitis. The patient responded well to loperamide and dietary modifications. Although nivolumab rarely causes IMC, this occurrence requires proper management in order to avoid further complications.

Rituximab-Induced Colitis and Esophagitis in a Patient With Granulomatosis With Polyangiitis.

Granulomatosis with polyangiitis (GPA) is a small vessel vasculitis that affects many organ systems with varying disease severity. GPA commonly affects the sinuses and lung parenchyma. However, GPA can affect the gastrointestinal tract and may present as colitis. Immunosuppressive therapy, like rituximab (RTX), is used for the management of this disease. Rituximab is generally well-tolerated but has rare side effects that have been shown to mimic colitis in inflammatory diseases. Our case is a 44-year-old female with a history of GPA who presented with dysphagia, abdominal pain, and diarrhea. The patient received a maintenance dose of RTX six months before the presentation. The patient was seronegative for anti-neutrophilic cytoplasmic antibodies against proteinase 3 (PR3 ANCA). Infectious etiology was ruled out. Esophagogastroduodenoscopy (EGD) and colonoscopy showed esophageal bleeding ulcers and diffuse colonic inflammation, respectively. Pathology was consistent with esophagitis and colitis. Colonic mucosal biopsy failed to show evidence of vasculitis. The patient was treated with sucralfate and intravenous pantoprazole with an improvement in the symptoms. The repeat endoscopy on an outpatient basis showed the patient had full mucosal healing, including histological healing. Our patient likely had rituximab-induced colitis and esophagitis.

Immune mediated colitis: a surgical perspective.

BACKGROUND: This study aims to review and summarize the current up to date literature that explore the current treatment approaches to immune mediated colitis and the role of surgical specialties in the landscape of management. METHODS: A narrative review of papers was performed following a literature search through Medline, EMBASE and Cochrane Central databases pertaining to immune mediated colitis as an adverse event of cancer immunotherapy. RESULTS: Current guidelines for the diagnosis and treatment of immune mediated colitis mirror the approach to the workup of inflammatory bowel disease and guided by treating oncology and gastroenterology specialties. Immune mediated colitis however relies on surgical specific skills as a consequence of obtaining a diagnosis as well as in the management of complications that may arise. CONCLUSION: Immune mediate colitis management has largely been under the purview of medical specialties. This review explores the current landscape of managing immune mediated colitis from a surgical perspective and highlights key areas in which surgeons can engage in the multidisciplinary care of this condition. To facilitate prompt diagnosis and management of immune-mediated colitis, there is an increasing necessity for surgeons to become familiar with the latest multidisciplinary approaches and recommendations.

Diffuse Metastatic Melanoma in the GI Lumen Following Immune Checkpoint Inhibitor Colitis Treatment.

We describe the unique case of a 73-year-old man who developed diffuse metastatic melanoma throughout the GI tract following potent immunosuppressive treatment for his immune-mediated colitis. Diagnosis of his metastatic GI luminal disease was confirmed with colonoscopy and EGD biopsies. Immunosuppressive therapy including corticosteroids and vedolizumab is the mainstay treatment for immune-mediated colitis and has generally been thought to have a safe toxicity profile. This unique case of diffuse luminal metastasis of melanoma after intensive immunosuppressant treatment raised the concern of their long-term safety on the cancer outcome and the need for safer alternatives.

Immune checkpoint inhibitor-induced colitis complicated with inflammatory intestinal obstruction: a case report and literature review.

Background: The combination therapy using anti-angiogenic drugs and immune checkpoint inhibitors (ICIs) has an excellent safety profile and manageable toxicity. However, ICI therapy may lead to a variety of autoimmune events, known as immune-related adverse events (irAEs), which some secondary complications may occur, such as immune-mediated colitis (IMC) and secondary inflammatory intestinal obstruction. It could impact clinical assessments and treatment decisions. Although there are few reports about secondary inflammatory intestinal obstruction related IMC. Case Description: We report an adult patient who suffered from primary liver cancer, who accepted ICIs (sintilimab) combined with vascular endothelial growth factor (VEGF) inhibitor (bevacizumab). He suffered worsening diarrhea about 5 days following immunotherapy. Computed tomography (CT) revealed the thickening intestinal wall of colon and rectum and massive cerebral gas in the proximal colon cavity. He was hospitalized with a diagnosis of IMC and inflammatory intestinal obstruction. Finally, he underwent the therapeutic option using combined glucocorticoid and somatostatin. His symptoms eased within 3 weeks and he was discharged from the hospital. Conclusions: IMC with diarrhea as the main manifestation requires early diagnosis and timely treatment. If the condition progresses, inflammatory intestinal obstruction may occur and this is a life-threatening situation. It is effective to accept early glucocorticoid and somatostatin while casual surgery may aggravate intestinal inflammation and injury, even death.

Ipilimumab and Nivolumab-Induced Colitis in a Patient With Recurrent Metastatic Melanoma.

Ipilimumab and nivolumab are immune checkpoint inhibitors that have recently been used in the treatment of metastatic melanoma and other cancers. Immune-mediated colitis is one of their adverse events that need to be differentiated from low-grade diarrhea as one of the most common side effects. A 51-year-old woman with relapsed metastatic melanoma presented with intractable diarrhea, nausea, vomiting, and generalized abdominal pain. The patient had been treated with ipilimumab and nivolumab in the past two months. The infectious workup was inconclusive. Colonoscopy demonstrated severe colitis, and biopsies were consistent with colitis. Combination chemotherapy was stopped. The patient was treated with intravenous and oral steroids, and her symptoms improved. A combination of ipilimumab and nivolumab increases the chance of immune-mediated colitis, and steroids should be started promptly to avoid complications such as bowel perforation and toxic megacolon.

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

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

Metachronous Esophageal Ulcers after Immune-mediated Colitis Due to Immune Checkpoint Inhibitor Therapy: A Case Report and Literature Review.

Although cases of gastrointestinal toxicity of pembrolizumab have been reported, cases of acute immune-mediated colitis accompanied with metachronous esophageal disorders (esophagitis and ulcer) are rare. We herein report a case of acute colitis and metachronous esophageal ulcers due to an immune-related adverse event following concomitant pembrolizumab chemotherapy for lung adenocarcinoma. To our knowledge, there have so far been no reports of cases in which both acute immune-mediated colitis and metachronous esophageal ulcers developed. We therefore report the details of this case along with a review of the pertinent literature.

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.

Pembrolizumab-Induced Immune-Mediated Colitis in a Patient with Concurrent Clostridium Difficile Infection.

Pembrolizumab is a programmed death receptor-1 (PD-1) inhibitor that has been approved for treatment of a wide variety of malignancies. Immune-mediated colitis is a known but uncommon adverse effect of pembrolizumab. Symptoms of immune-mediated colitis can be similar to those of many other gastrointestinal illnesses, including Clostridium difficile infection (CDI). If not recognized and treated in a timely fashion, immune-mediated colitis can lead to significant morbidity in cancer patients. We report the case of a 56-year-old woman on pembrolizumab for metastatic non-small cell lung cancer (NSCLC) who presented with severe colitis symptoms and initially tested positive for CDI. Her colitis symptoms worsened despite appropriate treatment for CDI but later improved rapidly after systemic corticosteroid was started for suspected immune-mediated colitis. To our knowledge, this is the first reported case of concurrent pembrolizumab-induced colitis and CDI. Immune-mediated colitis should be considered in the differential diagnoses in patients on pembrolizumab or other immune checkpoint inhibitors who present with colitis symptoms, even when a concurrent infectious etiology is suspected.

Immune-Mediated Colitis.

PURPOSE OF REVIEW: This review addresses our current knowledge of immune-mediated colitis (IMC) and offers a practical guide to its management. RECENT FINDINGS: Due to the similarity in clinical, endoscopic, and histologic findings between IMC and inflammatory bowel disease (IBD), gastroenterologists have tailored their approach to IMC management to that of IBD. Immune checkpoint inhibitors (ICIs) are monoclonal antibodies that augment the T-cell anti-tumor response of the immune system and have demonstrated their importance in the treatment of a wide range of malignancies. With the growing benefits of ICIs, there are immune-related adverse events (irAEs) that mirror many known autoimmune diseases. Diarrhea and IMC are the most common and severe irAEs noted. No standardized guidelines exist in the management of these irAEs.

Nivolumab and immune-mediated colitis.

Nivolumab is associated with a number of immune-regulated adverse events, including immune-mediated colitis and may present following the discontinuation of treatment. Current guidance suggests lower doses of methylprednisolone; however, we described faster resolution of the patient's symptoms compared to previous reported cases, using higher dosing, thereby minimizing hospitalization.

Immune checkpoint inhibitor-induced colitis: A comprehensive review.

Immune checkpoint inhibitors (ICIs) are monoclonal antibodies that target down-regulators of the anti-cancer immune response: Cytotoxic T-lymphocyte antigen-4, programmed cell death protein-1, and its ligand programmed death-ligand 1. ICIs have revolutionized the treatment of a variety of malignancies. However, many immune-related adverse events have also been described which mainly occurs as the immune system becomes less suppressed, affecting various organs including the gastrointestinal tract and causing diarrhea and colitis. The incidence of immune-mediated colitis (IMC) ranges from 1%-25% depending on the type of ICI and if used in combination. Endoscopically and histologically there is a significant overlap between IMC and inflammatory bowel disease, however more neutrophilic inflammation without chronic inflammation is usually present in IMC. Corticosteroids are recommended for grade 2 or more severe colitis while holding the immunotherapy. About one third to two thirds of patients are steroid refractory and benefit from infliximab. Recently vedolizumab has been found to be efficacious in steroid and infliximab refractory cases. While in grade 4 colitis, the immunotherapy is permanently discontinued, the decision is controversial in grade 3 colitis.