[Hepatic and digestive adverse events of immune checkpoint inhibitors (anti-CTLA-4 and, anti-PD-1/PD-L1): A clinico-pathological review]

Risk Factors for Immune Checkpoint Inhibitor-Induced Liver Injury and the Significance of Liver Biopsy

Immune checkpoint inhibitor (ICI)-induced liver injury (LI) is a common adverse event, but the clinical characteristics based on the classification of hepatocellular injury and cholestatic types are not fully evaluated. This study aims to analyze risk factors and histological findings in relation to the classification of ICI-induced LI. In total, 254 ICI-induced LI patients among 1086 treated with ICIs between September 2014 and March 2022 were classified according to the diagnostic criteria for drug-induced LI (DILI), and their risk factors and outcomes were evaluated. Kaplan-Meier analyses showed that overall survival in patients with hepatocellular-injury-type LI was significantly longer than others (p < 0.05). Regarding pre-treatment factors, the lymphocyte count was significantly higher in patients with ICI-induced LI, especially in hepatocellular-injury-type LI. Gamma glutamyl transferase (γGTP) and alkaline phosphatase (ALP) were also significantly lower in patients with ICI-induced LI (p < 0.05). Multivariate analyses revealed that malignant melanoma, high lymphocyte count, and low ALP levels were extracted as factors contributing to hepatocellular-injury-type LI. The histological findings among 37 patients diagnosed as ICI-induced LI via liver biopsy also revealed that the spotty/focal necrosis was significantly frequent in hepatocellular-injury-type LI, whereas ductular reactions were frequently observed in cholestatic-type LI. It is suggested that the histological inflammation pattern in patients with LI is closely correlated with the type of DILI.

The ABC of Immune-Mediated Hepatitis during Immunotherapy in Patients with Cancer: From Pathogenesis to Multidisciplinary Management

Immune-mediated hepatotoxicity (IMH) is not-so-rare complication during treatment with immune checkpoint inhibitors (ICIs). This narrative review aims to report the current knowledge on hepatic immune-related adverse events (irAEs) during immunotherapy from pathogenesis to multidisciplinary management. The majority of cases of IMH are asymptomatic and only a few patients may have clinical conditions. The severity of IMH is usually stratified according to Common Terminology for Clinical Adverse Events (CTCAE) criteria, but these scores may overestimate the clinical severity of IMH compared to the Drug-Induced Liver Injury Network (DILIN) scale. The differential diagnosis of IMH is challenging because the elevated liver enzymes can be due to a number of etiologies such as viral infection, autoimmune and metabolic diseases, liver metastases, biliary diseases, and other drugs. The cornerstones of IMH management are represented by withholding or delaying ICI administration and starting immunosuppressive therapy. A multidisciplinary team, including oncologists, hepatologists, internists, and emergency medicine physicians, is essential for the management of IMH.

[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.

Immunotherapy and Gene Therapy: New Challenges in the Diagnosis and Management of Drug-Induced Liver Injury

In the last 5 years, the landscape of oncologic treatment has been deeply modified with the development and use of immune checkpoint inhibitors (ICIs) that exert their antitumoral effect by reverting the exhausted phenotype of tumor-infiltrating lymphocytes. This innovative therapeutic strategy has widely changed the prognosis of some advanced neoplastic diseases such as melanoma and lung cancer, providing durable remission for a significant number of patients. Unfortunately, immune-related adverse events (irAEs), especially ICI-induced hepatitis, may be very severe in some cases, impairing the prognosis of the patient. Guidelines available today on the diagnosis and management of ICI-induced hepatitis are mainly based on expert opinions and case series. This lack of large data is explained not only by the low incidence of hepatic adverse events but also by their clinical heterogeneity and variable severity. In this article, we will review the clinical, biological, and histological characteristics of ICI-induced liver injury. We will discuss the current knowledge on their pathological mechanisms and their therapeutic strategy based on immunosuppressive treatment for more severe cases. Regarding severity assessment, we will discuss the gap between the oncologist and the hepatologist's point of view, highlighting the need for multidisciplinary management. While initially developed for notably less frequent diseases than neoplastic ones, gene therapy is going to be a revolution for the treatment of diseases not responding to pharmacological therapy. Limited but growing data describe liver injury after the administration of such therapy whose exact physiopathology remains unknown. In this article, we will discuss the available data supporting the role of gene therapies in the onset of drug-induced liver injury and related mechanisms. We will describe the clinical context, the biological and histological features, and the management currently proposed.

Checkpoint Inhibitor Colitis Shows Drug-Specific Differences in Immune Cell Reaction That Overlap With Inflammatory Bowel Disease and Predict Response to Colitis Therapy

OBJECTIVES

Checkpoint inhibitor (CPI)-associated colitis can limit therapy and has resemblance to inflammatory bowel disease (IBD). Studies exploring mechanistic similarities between these colitides are limited, yet therapeutic targets for either disorder could emerge from shared pathophysiology.

METHODS

The morphology and inflammatory content of colonic biopsy specimens from anti-CTLA-4 and anti-PD-1/PD-L1 antibody-treated patients with CPI colitis were compared with initial biopsy specimens from patients with IBD. Predictors of the need for infliximab were sought in CPI patients.

RESULTS

Biopsy specimens from CPI patients showed significantly lower chronicity scores and similar activity scores compared with patients with IBD. Anti-CTLA-4 and IBD groups showed equivalent CD8, CD4, PD-1, and PD-L1 expression, while FoxP3 scores were lower and CD68 scores were higher in anti-CTLA-4 compared with IBD biopsy specimens. Anti-PD-1/PD-L1 group had lower scores for CD8, CD4, and PD-1 and equivalent scores for FoxP3, PD-L1, and CD68 compared with IBD. Anti-CTLA-4 biopsy specimens had higher scores for CD8, PD-1, PD-L1, and CD68 than anti-PD-1/PD-L1 biopsy specimens. CD8/FoxP3 ratios and CD68 scores were higher among CPI patients requiring infliximab therapy for colitis compared with those responding to steroids.

CONCLUSIONS

The proinflammatory immune phenotype of anti-CTLA-4-associated colitis has significant overlap with IBD. CD8/FoxP3 ratios may predict therapeutic response in CPI-associated colitis.

Liver toxicity as a limiting factor to the increasing use of immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) improve clinical outcomes in patients suffering from different types of cancer. Liver toxicity is one of the immune-related adverse events associated with immunotherapy; although not common, its management is challenging as it is extremely heterogeneous in terms of presentation and severity. Differences in the development and evolution of ICI-related toxicity in healthy or cirrhotic livers have not yet been elucidated. Assessing causality is key to diagnosing ICI-induced liver toxicity; liver biopsies can assist not only in the differential diagnosis but also in assessing the severity of histological liver damage. The current classification of severity overestimates the grade of liver injury and needs to be revised to reflect the views of hepatologists. Spontaneous improvements in ICI-related liver toxicity have been reported, so corticosteroid therapy should probably be individualised not systematic. The reintroduction of ICIs in a patient with previous immune-mediated hepatitis may be possible, but the risk/benefit ratio should be considered, as the risk factors for hepatitis recurrence are currently unclear. The management of these patients, requiring a balance between efficacy, toxicity and specific treatments, necessitates multidisciplinary collaboration. The incidence of immune-related liver toxicity will continue to rise based on the increasing use of ICIs for most cancers, mandating improved understanding and management of this complication.

[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.