Checkpoint Inhibitors and the Gut

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

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

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.

The Role of Abdominal Surgery in Refractory Immune Checkpoint Inhibitor Enterocolitis: A Case Report

This article describes the case of a 73-year-old patient with grade 3 immune checkpoint inhibitor (ICI)-induced enteritis. Five different immunosuppressive agents (glucocorticoids, high-dose infliximab, methotrexate, mycophenolate mofetil, and vedolizumab) were administered, however, with no clinical or radiographical benefit. A laparotomy was performed, as the patient showed signs of intestinal obstruction, with a segmental resection of the ileal loop. Biopsy results showed multiple fibrotic strictures. The current treatment guidelines for ICI enterocolitis only include drugs as a treatment option. Nevertheless, it remains important to consider early surgical intervention in order to avoid serious complications due to persistent and pronounced inflammation. The current case highlights the importance of surgery as a treatment modality in the multidisciplinary approach for ICI-induced enteritis, which should be taken into consideration after second- or third-line treatment.

Check this out: treatment paradigms in immune-checkpoint inhibitor colitis

PURPOSE OF REVIEW

Immune checkpoint inhibitors (ICI) have become a pillar of cancer therapy for many people around the world. However, up to two-thirds of all patients undergoing ICI therapy will have immune-related adverse events (irAEs), including immune-checkpoint inhibitor colitis (ICIC). This review summarizes the most valuable and currently available information about the mechanism, diagnosis, and management of ICIC.

RECENT FINDINGS

Recent findings include several developments on the leading theories for the mechanisms of ICIC such as the role of the gut microbiome. New emerging therapy strategies include tocilizumab, ustekinumab, mycophenolate mofetil, and calcineurin inhibitors.

SUMMARY

The occurrence of irAEs remains a limiting factor for the use of immunotherapy in cancer treatment. Prompt diagnosis of ICIC with endoscopy and histologic confirmation can lead to early utilization of known effective treatments such as corticosteroids, infliximab, vedolizumab, and other emerging therapy strategies. We summarize the key points of this review article in our abstract video, Supplemental Digital Content 1, http://links.lww.com/COG/A44.

Comment on “Disease exacerbation is common in inflammatory bowel disease patients treated with immune checkpoint inhibitors for malignancy”

We recently read with interest the original research article entitled "Disease exacerbation is common in inflammatory bowel disease patients treated with immune checkpoint inhibitors for malignancy". The abovementioned article is an observational retrospective cohort study, which could be of particular value for clinicians to understand how immunotherapy affects pre-existing enteral disease in inflammatory bowel disease patients. Although we appreciate the endeavor of Samuel Rubin et al, based on our in-depth analysis, we detected a potential shortcoming in this article; thus, we present our comments in this letter. If the authors contemplate these comments on their relevant research, we believe that their contribution would be considerable for future studies.