Case Report: Fulminant Celiac Disease With Combination Immune Checkpoint Therapy

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.

Immune mechanisms of toxicity from checkpoint inhibitors

Immunotherapy has changed the treatment landscape for cancer over the past decade. Inhibitors of the immune checkpoint proteins cytotoxic T lymphocyte antigen (CTLA)-4, programmed death (PD)-1, and PD ligand 1 (PD-L1) can induce durable remissions in a subset of patients with metastatic disease. However, these treatments can be limited by inflammatory toxicities that can affect any organ system in the body and in some cases can be life threatening. Considerable progress has been made in understanding the drivers of these toxicities as well as effective management strategies. Further research into understanding the molecular and cellular mechanisms that drive toxicity will enable better prediction of toxicity and development of optimized therapies for these toxicities that avoid interfering with antitumor immunity. In this review, we discuss our current understanding of the inflammatory toxicities from immune checkpoint inhibitors (ICIs) and propose optimal treatment strategies for these toxicities.

An updated review of gastrointestinal toxicity induced by PD-1 inhibitors: from mechanisms to management

PD-1 inhibitors, as one of commonly used immune checkpoint inhibitors, enable T-cell activation and prevent immune escape by blocking the PD-1/PD-L1 signaling pathway. They have transformed the treatment landscape for cancer in recent years, due to the advantages of significantly prolonging patients' survival and improving their life quality. However, the ensuing unpredictable immune-related adverse effects (irAEs) plague clinicians, such as colitis and even potentially fatal events like intestinal perforation and obstruction. Therefore, understanding the clinical manifestations and grading criteria, underlying mechanisms, available diverse therapies, accessible biomarkers, and basis for risk stratification is of great importance for the management. Current evidence suggests that irAEs may be a marker of clinical benefit to immunotherapy in patients, so whether to discontinue PD-1 inhibitors after the onset of irAEs and rechallenge after remission of irAEs requires further evaluation of potential risk-reward ratios as well as more data from large-scale prospective studies to fully validate. At the end, the rare gastrointestinal toxicity events caused by PD-1 inhibitors are also sorted out. This review provides a summary of available data on the gastrointestinal toxicity profile caused by PD-1 inhibitors, with the aim of raising clinicians' awareness in daily practice, so that patients can safely benefit from therapy.

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.

Primate liver tissue substrate in indirect immunofluorescence diagnostics for patients with dermatitis herpetiformis and celiac disease

Introduction

Dermatitis herpetiformis (DH) is a rare autoimmune, polymorphous blistering disorder, characterized by severe itch or burning sensation, which represents the cutaneous manifestation of celiac disease (CD). The current estimation of DH versus CD is around 1:8 and the affected individuals have a genetic predisposition. Pathogenetically, IgA autoantibodies against the epidermal transglutaminase, an essential constituent of the epidermis, cause DH and are reported to develop through cross-reaction with the tissue transglutaminase, with IgA auto-antibodies causing CD. Immunofluorescence techniques allow for a rapid diagnostics of the disease using patient sera. Evaluation of IgA endomysial deposition with indirect immunofluorescence on monkey oesophagus is highly specific, but moderately sensitive, with some operator-dependent variability. Recently, indirect immunofluorescence with monkey liver as a substrate has been proposed as an alternative, well-functioning diagnostic approach with higher sensitivity in CD.

Methods

The objective of our study was to evaluate whether monkey oesophagus or liver tissue shows advantage for diagnostics in patients with DH, compared to CD. To that end, sera of 103 patients with DH (n=16), CD (n=67) and 20 controls ere compared by 4 blinded experienced raters.

Results

For DH, we found a sensitivity of 94.2% for monkey liver (ML) compared to 96.2% in monkey oesophagus (ME), while specificity in ML was superior (91.6% versus 75%) to ME. In CD, ML had a sensitivity of 76.9% (ME 89.1%) and specificity of 98.3% (ME 94.1%).

Discussion

Our data show that ML substrate is well suitable for DH diagnostics.

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.