Activation and transcriptional profile of monocytes and CD8+ T cells are altered in checkpoint inhibitor-related hepatitis

Monocyte-related markers as predictors of immune checkpoint inhibitor efficacy and immune-related adverse events: a systematic review and meta-analysis

The efficacy and off-target effects of immune checkpoint inhibitors (ICI) in cancer treatment vary among patients. Monocytes likely contribute to this heterogeneous response due to their crucial role in immune homeostasis. We conducted a systematic review and meta-analysis to evaluate the impact of monocytes on ICI efficacy and immune-related adverse events (irAEs) in patients with cancer. We systematically searched PubMed, Web of Science, and Embase for clinical studies from January 2000 to December 2023. Articles were included if they mentioned cancer, ICI, monocytes, or any monocyte-related terminology. Animal studies and studies where ICIs were combined with other biologics were excluded, except for studies where two ICIs were used. This systematic review was registered with PROSPERO (CRD42023396297) prior to data extraction and analysis. Monocyte-related markers, such as absolute monocyte count (AMC), monocyte/lymphocyte ratio (MLR), specific monocyte subpopulations, and m-MDSCs were assessed in relation to ICI efficacy and safety. Bayesian meta-analysis was conducted for AMC and MLR. The risk of bias assessment was done using the Cochrane-ROBINS-I tool. Out of 5787 studies identified in our search, 155 eligible studies report peripheral blood monocyte-related markers as predictors of response to ICI, and 32 of these studies describe irAEs. Overall, based on 63 studies, a high MLR was a prognostic biomarker for short progression-free survival (PFS) and overall survival (OS) hazard ratio (HR): 1.5 (95% CI: 1.21-1.88) and 1.52 (95% CI:1.13-2.08), respectively. The increased percentage of classical monocytes was an unfavorable predictor of survival, while low baseline rates of monocytic myeloid-derived suppressor cells (m-MDSCs) were favorable. Elevated intermediate monocyte frequencies were associated but not significantly correlated with the development of irAEs. Baseline monocyte phenotyping may serve as a composite biomarker of response to ICI; however, more data is needed regarding irAEs. Monocyte-related variables may aid in risk assessment and treatment decision strategies for patients receiving ICI in terms of both efficacy and safety.

Inflammation and Immunity in Liver Neoplasms: Implications for Future Therapeutic Strategies

Over the past two decades, the "hallmarks of cancer" have revolutionized cancer research and highlighted the crucial roles of inflammation and immunity. Protumorigenic inflammation promotes cancer development along with inhibition of antitumor immunity, shaping the tumor microenvironment (TME) toward a tumor-permissive state and further enhancing the malignant potential of cancer cells. This immunosuppressive TME allows tumors to evade immunosurveillance. Thus, understanding the complex interplay between tumors and the immune system within the TME has become pivotal, especially with the advent of immunotherapy. Although immunotherapy has achieved notable success in many malignancies, primary liver cancer, particularly hepatocellular carcinoma, presents unique challenges. The hepatic immunosuppressive environment poses obstacles to the effectiveness of immunotherapy, along with high mortality rates and limited treatment options for patients with liver cancer. In this review, we discuss current understanding of the complex immune-mediated mechanisms underlying liver neoplasms, focusing on hepatocellular carcinoma and liver metastases. We describe the molecular and cellular heterogeneity within the TME, highlighting how this presents unique challenges and opportunities for immunotherapy in liver cancers. By unraveling the immune landscape of liver neoplasms, this review aims to contribute to the development of more effective therapeutic interventions, ultimately improving clinical outcomes for patients with liver cancer.

Drug-Induced Liver Injury Associated With Emerging Cancer Therapies

Targeted therapies and immunotherapies have shown great promise as best-in-class treatments for several cancers with respect to efficacy and safety. While liver test abnormalities are rather common in patients treated with kinase inhibitors or immunotherapy, events of severe hepatotoxicity in these patients are rare in comparison with those associated with chemotherapeutics. The underlying mechanisms and risk factors for severe hepatotoxicity with novel oncology therapies are not well understood, complicating the drug-induced liver injury (DILI) risk assessment in the preclinical and clinical phases of drug development. The epidemiological and clinical characteristics, as well as mechanisms of liver toxicity, are described here to the current state of knowledge. Tools to study and assess the risk of DILI during drug development are concisely summarised, focusing on caveats thereof for novel oncology treatments. Emerging tools to optimise safety assessments and gather additional mechanistic insights into DILI are introduced. Particularly in oncology, where standard liver signals during drug development are tolerated to a marginally higher degree than in other indications due to the life-saving, life-extending and quality-of-life improvements for patients with severe or advanced cancers versus previous standard-of-care therapeutics, safety assessments must be tailored to the drug and indication. Trends in patient safety-centred drug development programmes and regulatory approval processes must continually be revisited and streamlined via obtaining an overall greater understanding of DILI and the tools available to assess mechanisms of injury, frequency, severity and prognosis.

Immune-mediated liver injury from checkpoint inhibitors: mechanisms, clinical characteristics and management

Immunotherapy has changed the treatment landscape for patients with cancer in the past decade. Immune checkpoint inhibitor (ICI)-based therapies have proven effective in a range of malignancies, including liver and gastrointestinal cancers, but they can cause diverse off-target organ toxicities. With the increasingly wider application of these drugs, immune-mediated liver injury from ICIs has become a commonly encountered challenge in clinical hepatology and gastroenterology. In this Review, we discuss the evidence from human and animal studies on the immunological mechanisms of immune-mediated liver injury from ICIs and summarize its clinical features and practical considerations for its management.

Immune-Mediated Liver Injury From Checkpoint Inhibitor: An Evolving Frontier With Emerging Challenges

Over the past decade, immune checkpoint inhibitors (ICIs) have transformed the treatment of cancer, though they come with the risk of immune-related adverse (irAEs) events such as hepatotoxicity or Immune-mediated Liver Injury from Checkpoint Inhibitors (ILICI). ILICI is a serious irAE that, when severe, requires cessation of ICI and initiation of immunosuppression. Cytotoxic T Lymphocytes (CTLs) play a central role in ILICI; however, they are just part of the picture as immunotherapy broadly impacts all aspects of the immune microenvironment and can directly and indirectly activate innate and adaptive immune cells. Clinically, as our understanding of this entity grows, we encounter new challenges. The presentation of ILICI is heterogeneous with respect to latency, pattern of injury (hepatitis vs. cholangitis) and severity. This review focuses on our knowledge regarding risk factors, presentation and treatment of ILICI including ILICI refractory to steroids. An emerging topic, the possibility of rechallenge while accepting some risk, in patients who experience ILICI but require immunotherapy, is also discussed. This review provides an update on the current knowns and unknowns in ILICI and highlights several knowledge gaps where studies are needed.

Hepatotoxicity in Cancer Immunotherapy: Diagnosis, Management, and Future Perspectives

Cancer immunotherapy, particularly immune checkpoint inhibitors, has positively impacted oncological treatments. Despite its effectiveness, immunotherapy is associated with immune-related adverse events (irAEs) that can affect any organ, including the liver. Hepatotoxicity primarily manifests as immune-related hepatitis and, less frequently, cholangitis. Several risk factors, such as pre-existing autoimmune and liver diseases, the type of immunotherapy, and combination regimens, play a role in immune-related hepatotoxicity (irH), although reliable predictive markers or models are still lacking. The severity of irH ranges from mild to severe cases, up to, in rare instances, acute liver failure. Management strategies require regular monitoring for early diagnosis and interventions, encompassing strict monitoring for mild cases to the permanent suspension of immunotherapy for severe forms. Corticosteroids are the backbone of treatment in moderate and high-grade damage, alone or in combination with additional immunosuppressive drugs for resistant or refractory cases. Given the relatively low number of events and the lack of dedicated prospective studies, much uncertainty remains about the optimal management of irH, especially in the most severe cases. This review presents the main features of irH, focusing on injury patterns and mechanisms, and provides an overview of the management landscape, from standard care to the latest evidence.

Immune checkpoint inhibitors and the liver: balancing therapeutic benefit and adverse events

Immune checkpoint inhibitors (ICI) have led to breakthrough improvements in the management of malignancy including hepatocellular (HCC) and biliary tract cancer, improving decades-old standards of care and increasing patient survival. In both liver tumour types, which commonly arise in the context of liver inflammation and underlying functional impairment, the lack of validated predictors of response underscores the need to balance predicted gains in survival with risk of treatment-related hepatoxicity and decompensation of underlying chronic liver disease.In addition, the liver is implicated in the toxicity associated with ICI therapy for non-liver cancers, which exhibits a high degree of variability in presentation and severity. An accurate assessment is mandatory for the diagnosis and management of ICI-induced liver injury.In this Recent Advances article, we provide an overview of the mechanisms of efficacy and toxicity of anticancer immunotherapy in liver tumours and liver toxicity in extrahepatic malignancies.We compare and contrast characteristics, management strategies and outcomes from immune-related liver injury in patients with chronic hepatitis/cirrhosis or with an underlying healthy liver and discuss the latest findings on how toxicity and decompensation may impact the outlook of patients with liver tumours and extrahepatic malignancies offering insights into the future directions of clinical research and practice in the field.

Outcomes of immune checkpoint inhibitor-induced liver toxicity managed by hepatologists in a multidisciplinary toxicity team

AIM

To detect immune-related adverse events (irAEs) early and treat them appropriately, our institute established an irAE-focused multidisciplinary toxicity team in cooperation with various departments. This study aimed to evaluate a consultation system involving a team of hepatologists in terms of its utility for the management of severe immune checkpoint inhibitor (ICI)-induced liver toxicity.

METHODS

To analyze the diagnosis and treatment of severe ICI-induced liver toxicity (Grade 2 requiring corticosteroid therapy and Grade 3 or higher), we examined patients' clinical courses before and after the hepatologist consultation system was established (pre-period, September 2014 to February 2019; post-period, March 2019 to March 2023).

RESULTS

The median follow-up period was 392 days. Of the 1247 patients with advanced malignancies treated with ICIs, 66 developed severe ICI-induced liver toxicity (n = 22 and 44 in the pre- and post-periods, respectively). In the pre-period, hepatologist consultations were sought for 15/22 patients, whereas in the post-period, 42/44 patients were referred to and treated by hepatologists. The time from the onset of liver toxicity to the consultation was significantly shorter in the post-period than in the pre-period (mean 1.9 vs. 6.5 days, respectively; p = 0.012). The number of patients with a biopsy-confirmed diagnosis of ICI-induced liver toxicity was significantly higher in the post-period than in the pre-period (n = 22 vs. n = 3, respectively; p = 0.006). Finally, there were no cases of immune-related cholangitis in the pre-period, compared to five cases in the post-period.

CONCLUSION

A hepatologist consultation system in an irAE-focused multidisciplinary toxicity team is useful for managing severe ICI-induced liver toxicity.

Cardiovascular toxicities of immune therapies for cancer - a scientific statement of the Heart Failure Association (HFA) of the ESC and the ESC Council of Cardio-Oncology

The advent of immunological therapies has revolutionized the treatment of solid and haematological cancers over the last decade. Licensed therapies which activate the immune system to target cancer cells can be broadly divided into two classes. The first class are antibodies that inhibit immune checkpoint signalling, known as immune checkpoint inhibitors (ICIs). The second class are cell-based immune therapies including chimeric antigen receptor T lymphocyte (CAR-T) cell therapies, natural killer (NK) cell therapies, and tumour infiltrating lymphocyte (TIL) therapies. The clinical efficacy of all these treatments generally outweighs the risks, but there is a high rate of immune-related adverse events (irAEs), which are often unpredictable in timing with clinical sequalae ranging from mild (e.g. rash) to severe or even fatal (e.g. myocarditis, cytokine release syndrome) and reversible to permanent (e.g. endocrinopathies).The mechanisms underpinning irAE pathology vary across different irAE complications and syndromes, reflecting the broad clinical phenotypes observed and the variability of different individual immune responses, and are poorly understood overall. Immune-related cardiovascular toxicities have emerged, and our understanding has evolved from focussing initially on rare but fatal ICI-related myocarditis with cardiogenic shock to more common complications including less severe ICI-related myocarditis, pericarditis, arrhythmias, including conduction system disease and heart block, non-inflammatory heart failure, takotsubo syndrome and coronary artery disease. In this scientific statement on the cardiovascular toxicities of immune therapies for cancer, we summarize the pathophysiology, epidemiology, diagnosis, and management of ICI, CAR-T, NK, and TIL therapies. We also highlight gaps in the literature and where future research should focus.

Exploring the role of the immune microenvironment in hepatocellular carcinoma: Implications for immunotherapy and drug resistance

Hepatocellular carcinoma (HCC), the most common type of liver tumor, is a leading cause of cancer-related deaths, and the incidence of liver cancer is still increasing worldwide. Curative hepatectomy or liver transplantation is only indicated for a small population of patients with early-stage HCC. However, most patients with HCC are not candidates for radical resection due to disease progression, leading to the choice of the conventional tyrosine kinase inhibitor drug sorafenib as first-line treatment. In the past few years, immunotherapy, mainly immune checkpoint inhibitors (ICIs), has revolutionized the clinical strategy for HCC. Combination therapy with ICIs has proven more effective than sorafenib, and clinical trials have been conducted to apply these therapies to patients. Despite significant progress in immunotherapy, the molecular mechanisms behind it remain unclear, and immune resistance is often challenging to overcome. Several studies have pointed out that the complex intercellular communication network in the immune microenvironment of HCC regulates tumor escape and drug resistance to immune response. This underscores the urgent need to analyze the immune microenvironment of HCC. This review describes the immunosuppressive cell populations in the immune microenvironment of HCC, as well as the related clinical trials, aiming to provide insights for the next generation of precision immunotherapy.

Immunotherapy-induced hepatitis in metastatic colorectal cancer: a systematic review and meta-analysis

Recent advances in immunotherapy using immune checkpoint inhibitors (ICIs) for various cancers have also highlighted a rise in immune-related adverse events, including hepatitis, potentially leading to the discontinuation of treatment. This study aimed to evaluate the prevalence of hepatitis in metastatic colorectal cancer (mCRC) patients undergoing different ICI therapies. An extensive search of PubMed, PubMed Central, and Google Scholar up to November 2023 identified relevant studies. After excluding non-English articles, case reports, reviews, ongoing trials, and studies combining other therapies, five studies qualified for inclusion. Data extraction and statistical analyses were performed using Excel and Comprehensive Meta-Analysis software, respectively. Results from a subgroup analysis indicated that the incidence of hepatitis was comparable among patients treated with PD-1 monotherapy, PDL-1 monotherapy, and combination PD-1 and CTLA-4 therapy, with rates of 2.6%, 2.2%, and 1.7% for any grade and 2.1%, 2.2%, and 1.7% for grade ≥3 hepatitis, respectively. Naive-treated mCRC patients exhibited higher hepatitis rates than those previously treated (3.2% vs 1.6% and 2.6% vs 1.6% for any grade and grade ≥3, respectively). This study underscores the similar risk of hepatitis across different ICI therapies, with an increased incidence in naive-treated mCRC patients.

Anti-PD-1/L1 antibody plus anti-VEGF antibody vs. plus VEGFR-targeted TKI as first-line therapy for unresectable hepatocellular carcinoma: a network meta-analysis

Background

This article is based on our previous research, which was presented at the 2023 ASCO Annual Meeting I and published in Journal of Clinical Oncology as Conference Abstract (JCO. 2023;41:e16148. doi: 10.1200/JCO.2023.41.16_suppl.e16148). Both anti-programmed death 1/ligand-1 (PD-1/L1) antibody + anti-vascular endothelial growth factor (VEGF) antibody (A + A) and anti-PD-1/L1 antibody + VEGF receptor (VEGFR)-targeted tyrosine kinase inhibitor (A + T) are effective first-line therapies for unresectable hepatocellular carcinoma. However, there lacks evidence from head-to-head comparisons between these two treatments. We conducted a network meta-analysis on the efficacy and safety of them.

Methods

After a rigorous literature research, 6 phase III trials were identified for the final analysis, including IMbrave150, ORIENT-32, COSMIC-312, CARES-310, LEAP-002, and REFLECT. The experiments were classified into three groups: A + A, A + T, and intermediate reference group. The primary endpoint was overall survival (OS), and secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and incidence of treatment-related adverse events (TRAEs). Hazard ratio (HR) with 95% confidence intervals (CI) for OS and PFS, odds ratio (OR) for ORR, and relative risk (RR) for all grade and grade ≥3 TRAEs were calculated. Under Bayesian framework, the meta-analysis was conducted using sorafenib as intermediate reference.

Results

With the rank probability of 96%, A + A showed the greatest reduction in the risk of death, without significant difference from A + T (HR: 0.82, 95% CI: 0.65-1.04). A + T showed the greatest effect in prolonging PFS and improving ORR with the rank probability of 77%, but there were no statistical differences with A + A. A + A was safer than A + T in terms of all grade of TRAEs (RR: 0.91, 95% CI: 0.82-1.00) and particularly in those grade ≥3 (RR: 0.65, 95% CI: 0.54-0.77).

Conclusions

A + A had the greatest probability of delivering the longest OS, while A + T was correlated with larger PFS benefits at the cost of a lower safety rate.

Hepatitis-related adverse events associated with immune checkpoint inhibitors in cancer patients: an observational, retrospective, pharmacovigilance study using the FAERS database

Background: Immune checkpoint inhibitors (ICIs), including anti-PD-1, anti-PD-L1 and anti-CTLA-4 antibodies, have become a standard treatment for multiple cancer types. However, ICIs can induce immune-related adverse events, with hepatitis-related adverse events (HRAEs) being of particular concern. Our objective is to identify and characterize HRAEs that exhibit a significant association with ICIs using real-world data. Methods: In this observational and retrospective pharmacovigilance study, we extracted real-world adverse events reports from the FDA Adverse Event Reporting System database spanning from the first quarter of 2004 to the first quarter of 2023. We conducted both Frequentist and Bayesian methodologies in the framework of disproportionality analysis, which included the reporting odds ratios (ROR) and information components (IC) to explore the intricate relationship between ICIs and HRAEs. Results: Through disproportionality analysis, we identified three categories of HRAEs as being significantly related with ICIs, including autoimmune hepatitis (634 cases, ROR 19.34 [95% CI 17.80-21.02]; IC025 2.43), immune-mediated hepatitis (546 cases, ROR 217.24 [189.95-248.45]; IC025 4.75), and hepatitis fulminant (80 cases, ROR 4.56 [3.65-5.70]; IC025 0.49). The median age of patients who report ICI-related HRAEs was 63 years (interquartile range [IQR] 53.8-72), with a fatal outcome observed in 24.9% (313/1,260) of these reports. Cases pertaining to skin cancer, lung cancer, and kidney cancer constituted the majority of these occurrences. Patients treated with anti-PD-1 or anti-PD-L1 antibodies exhibited a higher frequency of immune-mediated hepatitis in comparison to those undergoing anti-CTLA-4 monotherapy, with a ROR of 3.59 (95% CI 1.78-6.18). Moreover, the dual ICI therapy demonstrated higher reporting rates of ICI-related HRAEs compared to ICI monotherapy. Conclusion: Our findings confirm that ICI treatment carries a significant risk of severe HRAEs, in particular autoimmune hepatitis, immune-mediated hepatitis, and hepatitis fulminant. Healthcare providers should exercise heightened vigilance regarding these risks when managing patients receiving ICIs.

Immunological landscape of solid cancer: Interplay between tumor and autoimmunity

The immune system, a central player in maintaining homeostasis, emerges as a pivotal factor in the pathogenesis and progression of two seemingly disparate yet interconnected categories of diseases: autoimmunity and cancer. This chapter delves into the intricate and multifaceted role of the immune system, particularly T cells, in orchestrating responses that govern the delicate balance between immune surveillance and self-tolerance. T cells, pivotal immune system components, play a central role in both diseases. In autoimmunity, aberrant T cell activation drives damaging immune responses against normal tissues, while in cancer, T cells exhibit suppressed responses, allowing the growth of malignant tumors. Immune checkpoint receptors, example, initially explored in autoimmunity, now revolutionize cancer treatment via immune checkpoint blockade (ICB). Though effective in various tumors, ICB poses risks of immune-related adverse events (irAEs) akin to autoimmunity. This chapter underscores the importance of understanding tumor-associated antigens and their role in autoimmunity, immune checkpoint regulation, and their implications for both diseases. It also explores autoimmunity resulting from cancer immunotherapy and shared molecular pathways in solid tumors and autoimmune diseases, highlighting their interconnectedness at the molecular level. Additionally, it sheds light on common pathways and epigenetic features shared by autoimmunity and cancer, and the potential of repurposing drugs for therapeutic interventions. Delving deeper into these insights could unlock therapeutic strategies for both autoimmunity and cancer.

Diagnosis and management of immune mediated liver injury from checkpoint inhibitors

PURPOSE OF REVIEW

The aim is to summarize the latest data on the incidence, clinical manifestations, and management of immune- mediated liver injury from checkpoint inhibitors (ILICI).

RECENT FINDINGS

ILICI develops in 10-15% of oncology patients receiving immunotherapy with most having asymptomatic serum aminotransferase and/or alkaline phosphatase elevations. Most grade 1-2 ILICI patients improve with drug discontinuation and/or short-term oral corticosteroids. In contrast, the 2-3% with grade 3/4 hepatotoxicity frequently require oral or intravenous corticosteroids and some are hospitalized to initiate further immunosuppression with mycophenolate mofetil or azathioprine. Liver biopsy is generally reserved for patients with atypical features or those with severe hepatotoxicity who fail to respond to treatment. Up to 3% of ILICI patients with a cholestatic profile have MRI evidence of intra or extrahepatic cholangitis that responds poorly to immunosuppression. Most ILICI patients improve during follow-up and liver-related death is very uncommon (<1%). Up to 30% of rechallenged ILICI patients develop recurrent hepatotoxicity with a shorter latency.

SUMMARY

ILICI is increasingly encountered by gastroenterologists evaluating oncology patients with abnormal liver biochemistries. A stepwise approach to exclude viral hepatitis, alcohol, hepatic metastases, and pancreaticobiliary disease is recommended. The majority of ILICI patients fully recover with ICI discontinuation and short-term corticosteroids or a second line immunosuppressant.

Therapeutic inhibition of monocyte recruitment prevents checkpoint inhibitor-induced hepatitis

BACKGROUND

Checkpoint inhibitor-induced hepatitis (CPI-hepatitis) is an emerging problem with the widening use of CPIs in cancer immunotherapy. Here, we developed a mouse model to characterize the mechanism of CPI-hepatitis and to therapeutically target key pathways driving this pathology.

METHODS

C57BL/6 wild-type (WT) mice were dosed with toll-like receptor (TLR)9 agonist (TLR9-L) for hepatic priming combined with anti-cytotoxic T lymphocyte antigen-4 (CTLA-4) plus anti-programmed cell death 1 (PD-1) ("CPI") or phosphate buffered saline (PBS) control for up to 7 days. Flow cytometry, histology/immunofluorescence and messenger RNA sequencing were used to characterize liver myeloid/lymphoid subsets and inflammation. Hepatocyte damage was assessed by plasma alanine transaminase (ALT) and cytokeratin-18 (CK-18) measurements. In vivo investigations of CPI-hepatitis were carried out in Rag2-/- and Ccr2rfp/rfp transgenic mice, as well as following anti-CD4, anti-CD8 or cenicriviroc (CVC; CCR2/CCR5 antagonist) treatment.

RESULTS

Co-administration of combination CPIs with TLR9-L induced liver pathology closely resembling human disease, with increased infiltration and clustering of granzyme B+perforin+CD8+ T cells and CCR2+ monocytes, 7 days post treatment. This was accompanied by apoptotic hepatocytes surrounding these clusters and elevated ALT and CK-18 plasma levels. Liver RNA sequencing identified key signaling pathways (JAK-STAT, NF-ΚB) and cytokine/chemokine networks (Ifnγ, Cxcl9, Ccl2/Ccr2) as drivers of CPI-hepatitis. Using this model, we show that CD8+ T cells mediate hepatocyte damage in experimental CPI-hepatitis. However, their liver recruitment, clustering, and cytotoxic activity is dependent on the presence of CCR2+ monocytes. The absence of hepatic monocyte recruitment in Ccr2rfp/rfp mice and CCR2 inhibition by CVC treatment in WT mice was able to prevent the development and reverse established experimental CPI-hepatitis.

CONCLUSION

This newly established mouse model provides a platform for in vivo mechanistic studies of CPI-hepatitis. Using this model, we demonstrate the central role of liver infiltrating CCR2+ monocyte interaction with tissue-destructive CD8+ T cells in the pathogenesis of CPI-hepatitis and highlight CCR2 inhibition as a novel therapeutic target.

An algorithm based on immunotherapy discontinuation and liver biopsy spares corticosteroids in two thirds of cases of severe checkpoint inhibitor-induced liver injury

BACKGROUND

There are few data on corticosteroids (CS)-sparing strategies for checkpoint inhibitor (ICI)-induced liver injury (ChILI).

AIM

We aimed to assess the performance of a 2-step algorithm for severe ChILI, based on ICI temporary discontinuation (step-1) and, if lack of biochemical improvement, CS based on the degree of necroinflammation at biopsy (step-2).

METHODS

Prospective study that included all subjects with grade 3/4 ChILI. Peripheral extended immunophenotyping was performed. Indication for CS: severe necroinflammation; mild or moderate necroinflammation with later biochemical worsening.

RESULTS

From 111 subjects with increased transaminases (January 2020 to August 2023), 44 were diagnosed with grade 3 (N = 35) or grade 4 (N = 9) ChILI. Main reason for exclusion was alternative diagnosis. Lung cancer (13) and melanoma (12) were the most common malignancies. ICI: 23(52.3%) anti-PD1, 8(18.2%) anti-PD-L1, 3(6.8%) anti-CTLA-4, 10(22.7%) combined ICI. Liver injury pattern: hepatocellular (23,52.3%) mixed (12,27.3%) and cholestatic (9,20.5%). 14(32%) presented bilirubin >1.2 mg/dL. Overall, 30(68.2%) patients did not require CS: 22(50.0%) due to ICI discontinuation (step-1) and 8/22 (36.4%) based on the degree of necroinflammation (step-2). Biopsy mainly impacted on grade 3 ChILI, sparing CS in 8 out of 15 (53.3%) non-improvement patients after ICI discontinuation. CD8+ HLA-DR expression (p = 0.028), central memory (p = 0.046) were lower in CS-free managed subjects, but effector-memory cells (p = 0.002) were higher. Time to transaminases normalisation was shorter in those CS-free managed (overall: p < 0.001, grade 3: p < 0.001). Considering our results, a strategy based on ICI discontinuation and biopsy for grade 3 ChILI is proposed.

CONCLUSIONS

An algorithm based on temporary immunotherapy discontinuation and biopsy allows CS avoidance in two thirds of cases of severe ChILI.

Updates in the pathogenesis and management of immune-related enterocolitis, hepatitis and cardiovascular toxicities

Immune checkpoint inhibitors (ICIs) have become a cornerstone of treatment for many solid organ malignancies. Alongside increasing use, the occurrence of immune-related adverse events (irAEs) has also increased and remains a significant challenge when treating patients with ICI. The underlying pathophysiology of irAE development for many organ systems is yet to be elucidated, but may involve unmasking of latent autoimmunity, increased T-cell recognition of shared antigens on cancer and normal tissue and ICI-triggered immune dysregulation with overactivation of proinflammatory pathways and suppression of immune control pathways. Management strategies for irAEs have historically been borrowed from paradigms for conventional autoimmune conditions such as inflammatory bowel disease and autoimmune hepatitis; however, recent translational efforts have clearly demonstrated key differences in underlying immune signalling pathways. As we begin to understand these differences, we must adapt a more targeted approach to immunosuppression and exercise a more nuanced approach with the multiple biologic agents available to mitigate ICI-related toxicity without reversing the antitumour effect of ICI. In this review, we focus on three key immune-related toxicities where recent clinical and translational work has provided nuanced insights into pathogenesis and treatment strategies: enterocolitis, hepatitis and cardiovascular toxicity including myocarditis.

Innate and adaptive immune cell interaction drives inflammasome activation and hepatocyte apoptosis in murine liver injury from immune checkpoint inhibitors

Immune checkpoints (CTLA4 & PD-1) are inhibitory pathways that block aberrant immune activity and maintain self-tolerance. Tumors co-opt these checkpoints to avoid immune destruction. Immune checkpoint inhibitors (ICIs) activate immune cells and restore their tumoricidal potential, making them highly efficacious cancer therapies. However, immunotolerant organs such as the liver depend on these tolerogenic mechanisms, and their disruption with ICI use can trigger the unintended side effect of hepatotoxicity termed immune-mediated liver injury from ICIs (ILICI). Learning how to uncouple ILICI from ICI anti-tumor activity is of paramount clinical importance. We developed a murine model to recapitulate human ILICI using CTLA4+/- mice treated with either combined anti-CTLA4 + anti-PDL1 or IgG1 + IgG2. We tested two forms of antisense oligonucleotides to knockdown caspase-3 in a total liver (parenchymal and non-parenchymal cells) or in a hepatocyte-specific manner. We also employed imaging mass cytometry (IMC), a powerful multiplex modality for immunophenotyping and cell interaction analysis in our model. ICI-treated mice had significant evidence of liver injury. We detected cleaved caspase-3 (cC3), indicating apoptosis was occurring, as well as Nod-like receptor protein 3 (NLRP3) inflammasome activation, but no necroptosis. Total liver knockdown of caspase-3 worsened liver injury, and induced further inflammasome activation, and Gasdermin-D-mediated pyroptosis. Hepatocyte-specific knockdown of caspase-3 reduced liver injury and NLRP3 inflammasome activation. IMC-generated single-cell data for 77,692 cells was used to identify 22 unique phenotypic clusters. Spatial analysis revealed that cC3+ hepatocytes had significantly closer interactions with macrophages, Kupffer cells, and NLRP3hi myeloid cells than other cell types. We also observed zones of three-way interaction between cC3+ hepatocytes, CD8 + T-cells, and macrophages. Our work is the first to identify hepatocyte apoptosis and NLRP3 inflammasome activation as drivers of ILICI. Furthermore, we report that the interplay between adaptive and innate immune cells is critical to hepatocyte apoptosis and ILICI.

Checkpoint inhibitor hepatotoxicity: pathogenesis and management

Immunotherapy, including immune checkpoint inhibitor (ICI) therapy, has been a paradigm shift in cancer therapeutics, producing durable cancer responses across a range of primary malignancies. ICI drugs increase immune activity against tumor cells, but may also reduce immune tolerance to self-antigens, resulting in immune-mediated tissue damage. ICI-associated hepatotoxicity usually manifests as hepatocellular enzyme elevation and may occur in 2%-25% of ICI-treated patients. Although ICI-associated hepatotoxicity is clinically and pathologically distinct from idiopathic autoimmune hepatitis, our understanding of its pathogenesis continues to evolve. Pending greater understanding of the pathophysiology, mainstay of management remains through treatment with high-dose corticosteroids. This approach works for many patients, but up to 30% of patients with high-grade hepatotoxicity may not respond to corticosteroids alone. Furthermore, atypical cholestatic presentations are increasingly recognized, and rare cases of fulminant hepatitis due to ICI hepatotoxicity have been reported. Optimal management for these challenging patients remains uncertain. Herein, we review the current understanding of pathogenesis of ICI-associated toxicities, with a focus on hepatotoxicity. Based on the existing literature, we propose evolving management approaches to incorporate strategies to limit excess corticosteroid exposure, and address rare but important presentations of cholestatic hepatitis and fulminant liver failure. Finally, as ICI hepatotoxicity frequently occurs in the context of treatment for advanced malignancy, we review the impact of hepatotoxicity and its treatment on cancer outcomes, and the overall safety of re-challenge with ICI, for patients who may have limited treatment options.

Immuno-inflammatory in vitro hepatotoxicity models to assess side effects of biologicals exemplified by aldesleukin

Introduction

Hepatotoxicity induced by immunotherapeutics is an appearing cause for immune-mediated drug-induced liver injury. Such immuno-toxic mechanisms are difficult to assess using current preclinical models and the incidence is too low to detect in clinical trials. As hepatotoxicity is a frequent reason for post-authorisation drug withdrawal, there is an urgent need for immuno-inflammatory in vitro models to assess the hepatotoxic potential of immuno-modulatory drug candidates. We developed several immuno-inflammatory hepatotoxicity test systems based on recombinant human interleukin-2 (aldesleukin).

Methods

Co-culture models of primary human CD8+ T cells or NK cells with the hepatocyte cell line HepaRG were established and validated with primary human hepatocytes (PHHs). Subsequently, the HepaRG model was refined by increasing complexity by inclusion of monocyte-derived macrophages (MdMs). The main readouts were cytotoxicity, inflammatory mediator release, surface marker expression and specific hepatocyte functions.

Results

We identified CD8+ T cells as possible mediators of aldesleukin-mediated hepatotoxicity, with MdMs being implicated in increased aldesleukin-induced inflammatory effects. In co-cultures of CD8+ T cells with MdMs and HepaRG cells, cytotoxicity was induced at intermediate/high aldesleukin concentrations and perforin was upregulated. A pro-inflammatory milieu was created measured by interleukin-6 (IL-6), c-reactive protein (CRP), interferon gamma (IFN-γ), and monocyte chemoattractant protein-1 (MCP-1) increase. NK cells responded to aldesleukin, however, only minor aldesleukin-induced cytotoxic effects were measured in co-cultures. Results obtained with HepaRG cells and with PHHs were comparable, especially regarding cytotoxicity, but high inter-donor variations limited meaningfulness of the PHH model.

Discussion

The in vitro test systems developed contribute to the understanding of potential key mechanisms in aldesleukin-mediated hepatotoxicity. In addition, they may aid assessment of immune-mediated hepatotoxicity during the development of novel immunotherapeutics.

Immune Checkpoint Inhibitor-Induced Liver Injury

In recent years cancer treatment has been revolutionized by the development and wide application of checkpoint inhibitor (CPI) drugs, which are a form of immunotherapy. CPI treatment is associated with immune-related adverse events, off-target tissue destructive inflammatory complications, which may affect a range of organs, with liver inflammation (hepatitis) being one of the more commonly noted events. This is a novel form of drug-induced liver injury and a rapidly evolving field, as our understanding of both the basic immunopathology of CPI hepatitis (CPI-H) and optimal clinical management, races to catch up with the increasing application of this form of immunotherapy in clinical practice. In this review, we summarize current evidence and understanding of CPI-H, from fundamental immunology to practical patient management.

CD4 T cells and toxicity from immune checkpoint blockade

Immune-related toxicities, otherwise known as immune-related adverse events (irAEs), occur in a substantial fraction of cancer patients treated with immune checkpoint inhibitors (ICIs). Ranging from asymptomatic to life-threatening, ICI-induced irAEs can result in hospital admission, high-dose corticosteroid treatment, ICI discontinuation, and in some cases, death. A deeper understanding of the factors underpinning severe irAE development will be essential for improved irAE prediction and prevention, toward maximizing the benefits and safety profiles of ICIs. In recent work, we applied mass cytometry, single-cell RNA sequencing, single-cell V(D)J sequencing, bulk RNA sequencing, and bulk T-cell receptor (TCR) sequencing to identify pretreatment determinants of severe irAE development in patients with advanced melanoma. Across 71 patients separated into three cohorts, we found that two baseline features in circulation-elevated activated CD4 effector memory T-cell abundance and TCR diversity-are associated with severe irAE development, independent of the affected organ system within 3 months of ICI treatment initiation. Here, we provide an extended perspective on this work, synthesize and discuss related literature, and summarize practical considerations for clinical translation. Collectively, these findings lay a foundation for data-driven and mechanistic insights into irAE development, with the potential to reduce ICI morbidity and mortality in the future.

The Combination of R848 with Sorafenib Enhances Antitumor Effects by Reprogramming the Tumor Immune Microenvironment and Facilitating Vascular Normalization in Hepatocellular Carcinoma

Novel promising strategies for combination with sorafenib are urgently needed to enhance its clinical benefit and overcome toxicity in hepatocellular carcinoma (HCC). the molecular and immunomodulatory antitumor effects of sorafenib alone and in combination with the new immunotherapeutic agent R848 are presented. Syngeneic HCC mouse model is presented to explore the antitumor effect and safety of three sorafenib doses alone, R848 alone, or their combination in vivo. R848 significantly enhances the sorafenib antitumor activity at a low subclinical dose with no obvious toxic side effects. Furthermore, the combination therapy reprograms the tumor immune microenvironment by increasing antitumor macrophages and neutrophils and preventing immunosuppressive signaling. Combination treatment promotes classical M1 macrophage-to-FTH1high M1 macrophage transition. The close interaction between neutrophils/classical M1 macrophages and dendritic cells promotes tumor antigen presentation to T cells, inducing cytotoxic CD8+ T cell-mediated antitumor immunity. Additionally, low-dose sorafenib, alone or combined with R848, normalizes the tumor vasculature, generating a positive feedback loop to support the antitumor immune environment. Therefore, the combination therapy reprograms the HCC immune microenvironment and normalizes the vasculature, improving the therapeutic benefit of low-dose sorafenib and minimizing toxicity, suggesting a promising novel immunotherapy (R848) and targeted therapy (tyrosine kinase inhibitors) combination strategy for HCC treatment.

Implication of the Gut Microbiome and Microbial-Derived Metabolites in Immune-Related Adverse Events: Emergence of Novel Biomarkers for Cancer Immunotherapy

Immune checkpoint inhibitors (ICIs) have changed how we think about tumor management. Combinations of anti-programmed death ligand-1 (PD-L1) immunotherapy have become the standard of care in many advanced-stage cancers, including as a first-line therapy. Aside from improved anti-tumor immunity, the mechanism of action of immune checkpoint inhibitors (ICIs) exposes a new toxicity profile known as immune-related adverse effects (irAEs). This novel toxicity can damage any organ, but the skin, digestive and endocrine systems are the most frequently afflicted. Most ICI-attributed toxicity symptoms are mild, but some are severe and necessitate multidisciplinary side effect management. Obtaining knowledge on the various forms of immune-related toxicities and swiftly changing treatment techniques to lower the probability of experiencing severe irAEs has become a priority in oncological care. In recent years, there has been a growing understanding of an intriguing link between the gut microbiome and ICI outcomes. Multiple studies have demonstrated a connection between microbial metagenomic and metatranscriptomic patterns and ICI efficacy in malignant melanoma, lung and colorectal cancer. The immunomodulatory effect of the gut microbiome can have a real effect on the biological background of irAEs as well. Furthermore, specific microbial signatures and metabolites might be associated with the onset and severity of toxicity symptoms. By identifying these biological factors, novel biomarkers can be used in clinical practice to predict and manage potential irAEs. This comprehensive review aims to summarize the clinical aspects and biological background of ICI-related irAEs and their potential association with the gut microbiome and metabolome. We aim to explore the current state of knowledge on the most important and reliable irAE-related biomarkers of microbial origin and discuss the intriguing connection between ICI efficacy and toxicity.

Immune-mediated hepatitis induced by immune checkpoint inhibitors: Current updates and future perspectives

In recent years, cancer immunotherapy has made remarkable achievements. Immune checkpoint inhibitors (ICIs) have been used successfully in several types of cancer in the past decade. However, expanded indication and increased use of Immune checkpoint inhibitors have resulted in increased reports of toxicity called immune-related adverse events (irAEs). Due to the unique immunological characteristics of the liver, a hepatic immune-related adverse events has also been reported, which is usually termed Immune-mediated hepatitis (IMH). So far, it is generally considered that the mechanism of IMH induced by Immune checkpoint inhibitors is mainly the overactivation of T cells. It has been reported that the incidence of IMH ranges from 1% to 15%. Because of the lack of specific markers, a diagnosis of exclusion of IMH is critical. Although most IMH is mild and recoverable, several death cases have been reported, which has been increasingly concerned. This review summarizes the current understanding of the pathophysiology, epidemiology, diagnosis, management and prognosis of IMH caused by Immune checkpoint inhibitors. It also discusses the controversial issues in IMH, such as the role of liver biopsy, grading criteria, risk factors, rational treatment strategies with steroids, and the timing of Immune checkpoint inhibitors rechallenging, which may provide helpful information for IMH in future clinical practice.

The Current status of steroid-refractory immune-checkpoint-inhibitor-related hepatotoxicity

ICI-related hepatotoxicity (IRH) is becoming more and more common as immune checkpoint inhibitors (ICIs) have begun to be increasingly approved and used in combination with other anti-tumor drugs worldwide. Steroids are the first choice for the treatment of IRH, but the subsequent optimal treatment algorithm remains unclear if the disease progresses to steroid-refractory IRH. Therefore, in this paper we reviewed all the pertinent literature on steroid-refractory IRH to the greatest extent possible in an attempt to provide information on which to base an update of the treatment algorithm for steroid-refractory IRH.

Incidence and severity of immune-related hepatitis after dual checkpoint therapy is linked to younger age independent of herpes virus immunity

BACKGROUND AND AIMS

Dual immune checkpoint blockade (ICB) therapy can result in immune-related-adverse events (irAE) such as ICB-hepatitis. An expansion of effector-memory (TEM) CD4 T cells associated with antiviral immunity against herpesviridae was implicated in ICB-hepatitis. Notably, these memory subsets are frequently associated with age. Here, we sought to understand baseline patient, immune and viral biomarkers associated with the development of ICB-hepatitis to identify currently lacking baseline predictors and test if an expansion of TEM or positive serology against herpesviridae can predict ICB-hepatitis.

METHODS

A discovery (n = 39) and validation cohort (n = 67) of patients with advanced melanoma undergoing anti-PD-1&anti-CTLA4 combination therapy (total n = 106) were analyzed for baseline clinical characteristics, occurrence of irAE and oncological outcomes alongside serological status for CMV, EBV and HSV. Immune populations were profiled by high-parametric flow cytometry (n = 29).

RESULTS

ICB-hepatitis occurred in 59% of patients within 100 days; 35.9% developed severe (CTCAE 3-4) hepatitis. Incidence of ICB-hepatitis was higher in the younger (< 55y: 85.7%) compared to older (> = 55y: 27.8%) age group (p = 0.0003), occured earlier in younger patients (p < 0.0001). The association of younger age with ICB-Hepatitis was also observed in the validation cohort (p = 0.0486). Incidence of ICB-hepatitis was also associated with additional non-hepatic irAE (p = 0.018), but neither positive IgG serostatus for CMV, EBV or HSV nor TEM subsets despite an association of T cell subsets with age.

CONCLUSION

Younger age more accurately predicts ICB-hepatitis after anti-PD-1&anti-CTLA4 checkpoint therapy at baseline compared to herpes virus serology or TEM subsets. Younger patients should be carefully monitored for the development of ICB-hepatitis.

Transcription analysis of chicken embryo fibroblast cells infected with the recombinant avian leukosis virus isolate GX14FF03

Infection with recombinant avian leukosis virus (ALV) has previously been linked to malignancies and immunosuppression. However, the processes behind the unique pathophysiology of recombinant ALV are poorly understood. In this study, we analyzed gene expression patterns in chicken fibroblast cells (CEFs) infected with the recombinant ALV isolate GX14FF03 and used the RNA-seq technique to perform a complete analysis of the transcribed mRNAs. A total of 907 significant differentially expressed genes (SDEGs) were identified. Among these SDEGs, the most significantly upregulated gene was interleukin 8-like 1 (IL8L1), while the most significantly downregulated gene was fibroblast growth factor 16 (FGF16). The 907 SDGEs were highly enriched (p < 0.05) for 252 Gene Ontology (GO) terms, including 197 BP, 3 CC, and 52 MF. According to KEGG data analysis, SDEGs are implicated in eight significant pathways (p < 0.05). Furthermore, protein-protein interaction (PPI) network analysis revealed that IL8L1 interacts with 17 genes. These findings shed light on the molecular mechanisms involved in recombinant ALV infection by showing the mRNA expression profile in CEFs infected with GX14FF03 virus.

Application of artificial liver in immune-related liver injury induced by immune checkpoint inhibitor: Case reports and review of the literature

The use of immune checkpoint inhibitors (ICIs) can improve survival of patients with malignant tumors, however, the ICI treatment is associated with unpredictable toxicity as immune-related adverse effects (irAEs). Here we report two cases of metastatic malignant gastrointestinal tumors where severe immune-mediated hepatotoxicity (IMH) developed, characterized by liver failure, after the ICI therapy. Through a strong immunosuppressive treatment and a non-biological artificial liver and supportive treatment, the liver function was restored in both cases, and the anti-tumor treatment effect was guaranteed. These results showed that the non-biological artificial liver could be capable of improve prognosis during the ICI therapy.

Circulating biomarkers of response to immunotherapy and immune-related adverse events

INTRODUCTION

Immune checkpoint blockade has revolutionized cancer treatment. However, response rates vary, and these treatments have a high rate of immune-related side effects, which can be limiting. Thus, tests to predict who will respond and who may experience side effects are of critical importance toward realizing the ultimate goal of precision oncology.

AREAS COVERED

We review several of the most recent advances in circulating biomarkers that have been reported to be useful in predicting response and immune-related adverse events (irAE) to checkpoint blockade immunotherapies (CBI). We focus on high-quality studies published within the last few years. We highlight significant findings, identify areas for improvement, and provide recommendations on how these biomarkers may be translated into clinical utility.

EXPERT OPINION

As newer immunotherapies are developed, there is a pressing need to identify circulating biomarkers that can help predict responses and side effects. Current studies are mostly small-scale and retrospective; there is a need for larger-scale and prospective studies to help validate several of the biomarkers detailed here. As oncology focuses more on precision-based approaches, it is likely that a combination of biomarkers, including circulating ones as detailed here, will have critical utility in guiding clinical decisions.

Immune-Mediated Hepatitis During Immune Checkpoint Inhibitor cancer Immunotherapy: Lessons From Autoimmune Hepatitis and Liver Immunology

Immune checkpoint inhibitors (ICI) are being increasingly used to successfully treat several types of cancer. However, due to their mode of action, these treatments are associated with several immune-related adverse events (irAEs), including immune-mediated autoimmune-like hepatitis in 5 to 10% of cases. The specific immune mechanism responsible for the development of immune-mediated liver injury caused by immune checkpoint inhibitors (ILICI) is currently unknown. This review summarizes the current knowledge on hepatic irAEs during cancer immunotherapy. It also addresses the clinical management of ILICI and how it is becoming an increasingly important clinical issue. Clinical, histological, and laboratory features of autoimmune hepatitis (AIH) and ILICI are compared, and their shared and distinctive traits are discussed in an effort to better understand the development of hepatic irAEs. Finally, based on the current knowledge of liver immunology and AIH pathogenesis, we propose a series of events that could trigger the observed liver injury in ICI-treated patients. This model could be useful in the design of future studies aiming to identify the specific immune mechanism(s) at play in ILICI and improve immune checkpoint inhibitor cancer immunotherapy.

The Role of Myeloid Cells in Hepatotoxicity Related to Cancer Immunotherapy

Drug-related hepatotoxicity is an emerging clinical challenge with the widening use of immunotherapeutic agents in the field of oncology. This is an important complication to consider as more immune oncological targets are being identified to show promising results in clinical trials. The application of these therapeutics may be complicated by the development of immune-related adverse events (irAEs), a serious limitation often requiring high-dose immunosuppression and discontinuation of cancer therapy. Hepatoxicity presents one of the most frequently encountered irAEs and a better understanding of the underlying mechanism is crucial for the development of alternative therapeutic interventions. As a novel drug side effect, the immunopathogenesis of the condition is not completely understood. In the liver, myeloid cells play a central role in the maintenance of homeostasis and promotion of inflammation. Recent research has identified myeloid cells to be associated with hepatic adverse events of various immune modulatory monoclonal antibodies. In this review article, we provide an overview of the role of myeloid cells in the immune pathogenesis during hepatoxicity related to cancer immunotherapies and highlight potential treatment options.

Exploring the Mechanisms Underlying the Cardiotoxic Effects of Immune Checkpoint Inhibitor Therapies

Adaptive immune response modulation has taken a central position in cancer therapy in recent decades. Treatment with immune checkpoint inhibitors (ICIs) is now indicated in many cancer types with exceptional results. The two major inhibitory pathways involved are cytotoxic T-lymphocyte-associated protein 4 (CTLA4) and programmed cell death protein 1 (PD-1). Unfortunately, immune activation is not tumor-specific, and as a result, most patients will experience some form of adverse reaction. Most immune-related adverse events (IRAEs) involve the skin and gastrointestinal (GI) tract; however, any organ can be involved. Cardiotoxicity ranges from arrhythmias to life-threatening myocarditis with very high mortality rates. To date, most treatments of ICI cardiotoxicity include immune suppression, which is also not cardiac-specific and may result in hampering of tumor clearance. Understanding the mechanisms behind immune activation in the heart is crucial for the development of specific treatments. Histological data and other models have shown mainly CD4 and CD8 infiltration during ICI-induced cardiotoxicity. Inhibition of CTLA4 seems to result in the proliferation of more diverse T0cell populations, some of which with autoantigen recognition. Inhibition of PD-1 interaction with PD ligand 1/2 (PD-L1/PD-L2) results in release from inhibition of exhausted self-recognizing T cells. However, CTLA4, PD-1, and their ligands are expressed on a wide range of cells, indicating a much more intricate mechanism. This is further complicated by the identification of multiple co-stimulatory and co-inhibitory signals, as well as the association of myocarditis with antibody-driven myasthenia gravis and myositis IRAEs. In this review, we focus on the recent advances in unraveling the complexity of the mechanisms driving ICI cardiotoxicity and discuss novel therapeutic strategies for directly targeting specific underlying mechanisms to reduce IRAEs and improve outcomes.

Immunotherapies for hepatocellular carcinoma

Liver cancer, more specifically hepatocellular carcinoma (HCC), is the second leading cause of cancer-related death and its incidence is increasing globally. Around 50% of patients with HCC receive systemic therapies, traditionally sorafenib or lenvatinib in the first line and regorafenib, cabozantinib or ramucirumab in the second line. In the past 5 years, immune-checkpoint inhibitors have revolutionized the management of HCC. The combination of atezolizumab and bevacizumab has been shown to improve overall survival relative to sorafenib, resulting in FDA approval of this regimen. More recently, durvalumab plus tremelimumab yielded superior overall survival versus sorafenib and atezolizumab plus cabozantinib yielded superior progression-free survival. In addition, pembrolizumab monotherapy and the combination of nivolumab plus ipilimumab have received FDA Accelerated Approval in the second-line setting based on early efficacy data. Despite these major advances, the molecular underpinnings governing immune responses and evasion remain unclear. The immune microenvironment has crucial roles in the development and progression of HCC and distinct aetiology-dependent immune features have been defined. Inflamed and non-inflamed classes of HCC and genomic signatures have been associated with response to immune-checkpoint inhibitors, yet no validated biomarker is available to guide clinical decision-making. This Review provides information on the immune microenvironments underlying the response or resistance of HCC to immunotherapies. In addition, current evidence from phase III trials on the efficacy, immune-related adverse events and aetiology-dependent mechanisms of response are described. Finally, we discuss emerging trials assessing immunotherapies across all stages of HCC that might change the management of this disease in the near future.

Mechanisms of immune checkpoint inhibitor-mediated liver injury

The immune checkpoints, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed cell death protein-1/ligand-1 (PD-1/PD-L1) are vital contributors to immune regulation and tolerance. Recently immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy; however, they come with the cost of immune related adverse events involving multiple organs such as the liver. Due to its constant exposure to foreign antigens, the liver has evolved a high capacity for immune tolerance, therefore, blockade of the immune checkpoints can result in aberrant immune activation affecting the liver in up to 20% of patients depending on the agent(s) used and underlying factors. This type of hepatotoxicity is termed immune mediated liver injury from checkpoint inhibitors (ILICI) and is more common when CTLA4 and PD-1/PD-L1 are used in combination. The underlying mechanisms of this unique type of hepatotoxicity are not fully understood; however, the contribution of CD8+ cytotoxic T lymphocytes, various CD4+ T cells populations, cytokines, and the secondary activation of the innate immune system leading to liver injury have all been suggested. This review summarizes our current understanding of the underlying mechanisms of liver injury in immunotherapy using animal models of ILICI and available patient data from clinical studies.

Biological Bases of Immune-Related Adverse Events and Potential Crosslinks With Immunogenic Effects of Radiation

Immune checkpoint inhibitors have gained an established role in the treatment of different tumors. Indeed, their use has dramatically changed the landscape of cancer care, especially for tumor types traditionally known to have poor outcomes. However, stimulating anticancer immune responses may also elicit an unusual pattern of immune-related adverse events (irAEs), different from those of conventional chemotherapy, likely due to a self-tolerance impairment featuring the production of autoreactive lymphocytes and autoantibodies, or a non-specific autoinflammatory reaction. Ionizing radiation has proven to promote both positive pro-inflammatory and immunostimolatory activities, and negative anti-inflammatory and immunosuppressive mechanisms, as a result of cross-linked interactions among radiation dose, the tumor microenvironment and the host genetic predisposition. Several publications argue in favor of combining immunotherapy and a broad range of radiation schedules, based on the recent evidence of superior treatment responses and patient survival. The synergistic modulation of the immune response by radiation therapy and immunotherapeutics, particularly those manipulating T-cell activation, may also affect the type and severity of irAEs, suggesting a relationship between the positive antitumor and adverse autoimmune effects of these agents. As yet, information on factors that may help to predict immune toxicity is still lacking. The aim of our work is to provide an overview of the biological mechanisms underlying irAEs and possible crosslinks with radiation-induced anticancer immune responses. We believe such an overview may support the optimization of immunotherapy and radiotherapy as essential components of multimodal anticancer therapeutic approaches. Challenges in translating these to clinical practice are discussed.

Gut-Liver Immune Traffic: Deciphering Immune-Pathogenesis to Underpin Translational Therapy

The tight relationship between the gut and liver on embryological, anatomical and physiological levels inspired the concept of a gut-liver axis as a central element in the pathogenesis of gut-liver axis diseases. This axis refers to the reciprocal regulation between these two organs causing an integrated system of immune homeostasis or tolerance breakdown guided by the microbiota, the diet, genetic background, and environmental factors. Continuous exposure of gut microbiome, various hormones, drugs and toxins, or metabolites from the diet through the portal vein adapt the liver to maintain its tolerogenic state. This is orchestrated by the combined effort of immune cells network: behaving as a sinusoidal and biliary firewall, along with a regulatory network of immune cells including, regulatory T cells and tolerogenic dendritic cells (DC). In addition, downregulation of costimulatory molecules on hepatic sinusoids, hepatocytes and biliary epithelial cells as well as regulating the bile acids chain also play a part in hepatic immune homeostasis. Recent evidence also demonstrated the link between changes in the gut microbiome and liver resident immune cells in the progression of cirrhosis and the tight correlation among primary sclerosing cholangitis (PSC) and also checkpoint induced liver and gut injury. In this review, we will summarize the most recent evidence of the bidirectional relationship among the gut and the liver and how it contributes to liver disease, focusing mainly on PSC and checkpoint induced hepatitis and colitis. We will also focus on completed therapeutic options and on potential targets for future treatment linking with immunology and describe the future direction of this research, taking advantage of modern technologies.

Immune-Mediated Drug-Induced Liver Injury: Immunogenetics and Experimental Models

Drug-induced liver injury (DILI) is a challenging clinical event in medicine, particularly because of its ability to present with a variety of phenotypes including that of autoimmune hepatitis or other immune mediated liver injuries. Limited diagnostic and therapeutic tools are available, mostly because its pathogenesis has remained poorly understood for decades. The recent scientific and technological advancements in genomics and immunology are paving the way for a better understanding of the molecular aspects of DILI. This review provides an updated overview of the genetic predisposition and immunological mechanisms behind the pathogenesis of DILI and presents the state-of-the-art experimental models to study DILI at the pre-clinical level.