Phenotypic Characteristics of PD-1 and CTLA-4 Expression in Symptomatic Acute Hepatitis A

Incomplete elimination of viral genomes is associated with chronic inflammation in nonhuman primate livers after AAV-mediated gene transfer

The liver is a unique organ where immunity can be biased toward ineffective response notably in the context of viral infections. Chronic viral hepatitis depends on the inability of the T-cell immune response to eradicate antigen. In the case of recombinant Adeno-Associated-Virus, used for therapeutic gene transfer, conflicting reports describe tolerance induction to different transgene products while other studies have shown conventional cytotoxic CD8+ T cell responses with a rapid loss of transgene expression. We performed a 1 year follow up of 6 non-human primates after all animals received an rAAV8 vector carrying the GFP transgene at doses of 7×1012 vg/kg. We report that despite anti-GFP peripheral cellular response and loss of hepatic transgene expression, we were still able to detect persisting viral genomes in the liver until 1-year post-injection. These viral genomes were associated with liver inflammation, fibrosis and signs of CD8 T cell exhaustion, including high expression of PD-1. Our study shows that AAV8-mediated gene transfer can results to loss of transgene expression in liver and chronic inflammation several months after gene transfer.

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.

Association of hepatitis B virus DNA levels with efficacy and safety and the impact of antiviral therapy on prognosis in liver cancer patients receiving immune checkpoint inhibitors therapy: a systematic review and meta-analysis

Background

The current evidence regarding the relationship between baseline hepatitis B virus (HBV) DNA levels and survival outcomes in liver cancer patients receiving immune checkpoint inhibitors (ICIs) remains inconsistent. Therefore, this review was intended to explore the impact of the baseline HBV-DNA level on the efficacy and safety of ICIs in patients with liver cancer.

Methods

Relevant studies were identified through a comprehensive search in PubMed, EMBASE, Cochrane Library, and Web of Science up to August 1, 2024. The outcomes were hazard ratios (HRs) for overall survival (OS) and progression-free survival (PFS), as well as odds ratios (ORs) for objective response rate (ORR), disease control rate (DCR) and HBV reactivation (HBVr). Subgroup analysis, publication bias, and sensitivity analysis were conducted with STATA 14.0.

Results

This meta-analysis comprised 17 articles involving a total of 2,130 patients. The pooled results demonstrated that high HBV DNA was associated with a worse OS (HR = 1.48 95% CI 1.11-1.96). Further subgroup analysis showed that there was no difference in OS between the high HBV DNA group and low HBV DNA group when all patients received antiviral treatment. No associations between baseline HBV DNA and PFS (HR = 1.08, 95% CI 0.90-1.29), ORR (OR = 0.91, 95% CI 0.65-1.28), or DCR (OR = 0.83, 95% CI 0.58-1.20) were observed. The risk of HBVr in the high HBV DNA group was lower than that in the low HBV DNA group (OR = 0.30, 95% CI 0.15-0.58), especially among patients who received antiviral therapy (OR = 0.42, 95% CI 0.18-0.98).

Conclusion

High HBV DNA was associated with worse OS, but not with PFS, ORR, or DCR in liver cancer patients receiving ICIs. When patients were simultaneously treated with antiviral treatment, elevated HBV DNA level had no unfavorable impact on the efficacy of ICIs. Furthermore, the risk of HBVr in the high HBV-DNA group was lower than that in the low HBV DNA group. More prospective studies with larger sample sizes are essential to confirm the results.

Impact of baseline hepatitis B virus viral load on the long-term prognosis of advanced hepatocellular carcinoma treated with immunotherapy

BACKGROUND

Although the combination of lenvatinib and PD-1 inhibitors has become the standard regimen for the treatment of advanced hepatocellular carcinoma (HCC), real data on the impact of baseline hepatitis B virus (HBV)-DNA levels on the clinical efficacy of this regimen is still limited.

AIM

To evaluate the effectiveness of camrelizumab combined with lenvatinib in patients with HCC at varying levels of HBV-DNA.

METHODS

One hundred and twenty patients with HCC who received camrelizumab and lenvatinib treatment were categorized into two cohorts: HBV-DNA ≤ 2000 (n = 66) and HBV-DNA > 2000 (n = 54). The main outcomes measured were overall survival (OS) and progression-free survival (PFS), while additional outcomes included the rate of objective response rate (ORR), disease control rate (DCR), and any negative events. Cox proportional hazards regression analysis revealed independent predictors of OS, leading to the creation of a nomogram incorporating these variables.

RESULTS

The median PFS was 8.32 months for the HBV-DNA ≤ 2000 group, which was similar to the 7.80 months observed for the HBV DNA > 2000 group (P = 0.88). Likewise, there was no notable variation in the median OS between the two groups, with durations of 13.30 and 14.20 months respectively (P = 0.14). The ORR and DCR were compared between the two groups, showing ORR of 19.70% vs 33.33% (P = 0.09) and DCR of 72.73% vs 74.07% (P = 0.87). The nomogram emphasized the importance of antiviral treatment as the main predictor of patient results, with portal vein tumor thrombus and Barcelona Clinic Liver Cancer staging following closely behind.

CONCLUSION

The clinical outcomes of patients with HBV-associated HCC treated with camrelizumab in combination with lenvatinib are not significantly affected by HBV viral load.

Impact of baseline hepatitis B virus viral load on the long-term prognosis of advanced hepatocellular carcinoma treated with immunotherapy

BACKGROUND

Although the combination of lenvatinib and PD-1 inhibitors has become the standard regimen for the treatment of advanced hepatocellular carcinoma (HCC), real data on the impact of baseline hepatitis B virus (HBV)-DNA levels on the clinical efficacy of this regimen is still limited.

AIM

To evaluate the effectiveness of camrelizumab combined with lenvatinib in patients with HCC at varying levels of HBV-DNA.

METHODS

One hundred and twenty patients with HCC who received camrelizumab and lenvatinib treatment were categorized into two cohorts: HBV-DNA ≤ 2000 (n = 66) and HBV-DNA > 2000 (n = 54). The main outcomes measured were overall survival (OS) and progression-free survival (PFS), while additional outcomes included the rate of objective response rate (ORR), disease control rate (DCR), and any negative events. Cox proportional hazards regression analysis revealed independent predictors of OS, leading to the creation of a nomogram incorporating these variables.

RESULTS

The median PFS was 8.32 months for the HBV-DNA ≤ 2000 group, which was similar to the 7.80 months observed for the HBV DNA > 2000 group (P = 0.88). Likewise, there was no notable variation in the median OS between the two groups, with durations of 13.30 and 14.20 months respectively (P = 0.14). The ORR and DCR were compared between the two groups, showing ORR of 19.70% vs 33.33% (P = 0.09) and DCR of 72.73% vs 74.07% (P = 0.87). The nomogram emphasized the importance of antiviral treatment as the main predictor of patient results, with portal vein tumor thrombus and Barcelona Clinic Liver Cancer staging following closely behind.

CONCLUSION

The clinical outcomes of patients with HBV-associated HCC treated with camrelizumab in combination with lenvatinib are not significantly affected by HBV viral load.

Hepatitis B virus reactivation in hepatocellular carcinoma patients after hepatic arterial infusion chemotherapy combined with and without immunotherapy

BACKGROUND

Hepatitis B virus (HBV) reactivation (HBVr) is a major concern for hepatocellular carcinoma (HCC) patients undergoing hepatic arterial infusion chemotherapy (HAIC) using mFOLFOX6 regimen. There is insufficient evidence to support the routine use of HAIC combined with immunotherapy in HCC patients with HBVr. The aim of this study was to examine the adverse events (AEs) related to HBVr in HCC patients after HAIC, with or without immunotherapy, and to assess the effectiveness of antiviral prophylaxis for HBVr.

METHODS

Medical records of HCC patients receiving HAIC combined with and without immunotherapy between January 2021 and June 2023 were reviewed. The patients were divided into two groups based on whether they received immunotherapy or not.

RESULTS

Out of the 106 patients, 32 (30.2%) developed HBVr. Among these, 23 eligible patients with HBVr were included, with 14 patients (61%) receiving immunotherapy and nine patients (39%) not receiving immunotherapy. Prior to HAIC treatment, four patients in each group had detectable HBV DNA with median titre of 3.66 × 102 IU/ml (patients with immunotherapy) and 1.98 × 102 IU/ml (patients without immunotherapy), respectively. Fifteen patients did not show detectable HBV DNA. At HBVr occurrence, the median HBV DNA level was 6.95 × 102 IU/ml for all patients, 4.82 × 102 IU/ml in patients receiving immunotherapy and 1.3 × 103 IU/ml in patients not receiving immunotherapy. Grade 3 hepatitis developed in 12 cases of all patients (12/23, 48%), including five patients with immunotherapy (56%) and seven patients without immunotherapy (78%). At the 3-month follow-up, HBV DNA was detected in 10 patients, with a median HBV DNA level of 2.05 × 102 IU/ml (range, 1.5 × 102- 3.55 × 102 IU/ml) in patients (7/10) with immunotherapy and 4.28 × 102 IU/ml (range, 1.15 × 102- 5.88 × 102 IU/ml) in patients (3/10) without immunotherapy. Intensified antiviral treatment was administered to all patients. No HBVr-related fatal events occurred.

CONCLUSION

HBVr can occur after HAIC combined with or without immunotherapy. The degree of liver damage did not differ significantly in patients treated with or without immunotherapy. Intensified antiviral treatment was found to be crucial for HCC patients with HBVr.

Programmed Cell Death Protein 1 Axis Inhibition in Viral Infections: Clinical Data and Therapeutic Opportunities

A vital function of the immune system is the modulation of an evolving immune response. It is responsible for guarding against a wide variety of pathogens as well as the establishment of memory responses to some future hostile encounters. Simultaneously, it maintains self-tolerance and minimizes collateral tissue damage at sites of inflammation. In recent years, the regulation of T-cell responses to foreign or self-protein antigens and maintenance of balance between T-cell subsets have been linked to a distinct class of cell surface and extracellular components, the immune checkpoint molecules. The fact that both cancer and viral infections exploit similar, if not the same, immune checkpoint molecules to escape the host immune response highlights the need to study the impact of immune checkpoint blockade on viral infections. More importantly, the process through which immune checkpoint blockade completely changed the way we approach cancer could be the key to decipher the potential role of immunotherapy in the therapeutic algorithm of viral infections. This review focuses on the effect of programmed cell death protein 1/programmed death-ligand 1 blockade on the outcome of viral infections in cancer patients as well as the potential benefit from the incorporation of immune checkpoint inhibitors (ICIs) in treatment of viral infections.

FoxP3, PD-1 and CTLA-4 are decreased significantly after a tenofovir therapy in patients with chronic hepatitis B

Background: FoxP3, PD-1 and CTLA-4 are upregulated in chronic viral infections, such as chronic HCV, chronic HBV and HIV infection. Materials & methods: During 1 year of tenofovir disoproxil fumarate (TDF) treatment in patients with chronic hepatitis B, we investigated the expression of FoxP3, PD-1 and CTLA-4. Peripheral blood mononuclear cells were isolated from the 30 study subjects at T0 (0 months), T3, T6 and T12 months after the commencement of TDF treatment. Results & conclusion: Expression of FoxP3, PD-1 and CTLA-4 was significantly decreased in T cells of patients with chronic hepatitis B under TDF treatment at T12, when compared with that at T0. A direct correlation was observed between FoxP3 and CTLA-4 expression in patients with chronic hepatitis B and the frequency of FoxP3 was positively associated with serum alanine aminotransferase levels.

The Role of PD-1 in Acute and Chronic Infection

PD-1 as an immune checkpoint molecule down-regulates T cell activity during immune responses in order to prevent autoimmune tissue damage. In chronic infections or tumors, lasting antigen-exposure leads to permanent PD-1 expression that can limit immune-mediated clearance of pathogens or degenerated cells. Blocking PD-1 can enhance T cell function; in cancer treatment PD-1 blockade is already used as a successful therapy. However, the role of PD-1 expression and blocking in the context of acute and chronic infections is less defined. Building on its success in cancer therapy leads to the hypothesis that blocking PD-1 in infectious diseases is also beneficial in acute or chronic infections. This review will focus on the role of PD-1 expression in acute and chronic infections with virus, bacteria, and parasites, with a particular focus on recent studies regarding PD-1 blockade in infectious diseases.

Hepatitis B virus reactivation in cancer patients with positive Hepatitis B surface antigen undergoing PD-1 inhibition

Background

Hepatitis B virus (HBV) reactivation is a serious complication in patients with cancers and HBV infection undergoing immunosuppressant treatment or chemotherapy. However, the safety of anti-programmed cell death (PD) -1 and anti-programmed cell death-ligand 1 (PD-L1) therapy in these patients is unknown because they were excluded from clinical trials of immunotherapy.

Methods

This retrospective cohort study involved consecutive hepatitis B surface antigen (HBsAg) -positive cancer patients who were referred to Sun Yat-sen University Cancer Center and received an anti-PD-1/PD-L1 antibody between January 1, 2015 and July 31, 2018. The primary end point was the rate of the occurrence of HBV reactivation.

Results

In total, 114 eligible patients were included, among whom 90 (79%) were male, and the median (range) age was 46 (16–76) years. Six patients (5.3%) developed HBV reactivation, occurring at a median of 18 weeks (range, 3–35 weeks) from the commencement of immunotherapy. Among these patients, all of them had undetectable baseline HBV DNA; one had prophylactic antiviral therapy while five did not; four were positive for Hepatitis B e antigen while the other two were negative. At reactivation, the median HBV DNA level was 3.89 × 10⁴ IU/mL (range, 1.80 × 10³–6.00 × 10⁷ IU/mL); five had HBV-related hepatitis and one exhibited increasing HBV DNA level without alanine transaminase elevation. No HBV-related fatal events occurred. The lack of antiviral prophylaxis was the only significant risk factor for HBV reactivation (odds ratio, 17.50 [95% CI, 1.95–157.07], P = .004).

Conclusions

HBV reactivation occurs in a subset of HBsAg-positive cancer patients undergoing anti-PD-1 or anti-PD-L1 immunotherapy. Regular monitoring of HBV DNA and antiviral prophylaxis are advised to prevent this potentially fatal complication.

CTLA‑4 interferes with the HBV‑specific T cell immune response (Review)

Hepatitis B virus (HBV) infection is a major cause of hepatic inflammation. Successful HBV clearance in patients is associated with sustained viral control by effector T cells. Compared with acute hepatitis B, chronic HBV infection is associated with the depletion of T cells, resulting in weak or absent virus-specific T cells reactivity, which is described as 'exhaustion'. This exhaustion is characterized by impaired cytokine production and sustained expression of multiple coinhibitory molecules. Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) is one of many coinhibitory molecules that can attenuate T cell activation by inhibiting costimulation and transmitting inhibitory signals to T cells. Persistent HBV infection results in the upregulation of CTLA-4 on hepatic CD8⁺ T cells. This prompts CD8⁺ T cell apoptosis, and the activation of cytotoxic T lymphocytes is blocked. Similar to CD8⁺ T cells, CD4⁺ T helper (Th) cell proliferation is hindered following CTLA-4 upregulation. In addition, the differentiation of CD4⁺ Th is polarized toward the Th2/peripherally-inducible T regulatory cell types, increasing the levels of anti-inflammatory cytokines. Conversely, the activation of proinflammatory cells (Th1 and follicular helper T) is blocked, and the levels of proinflammatory cytokines decline. This review summarizes the current literature relevant to T cell exhaustion in patients with HBV-related chronic hepatitis, and discusses the roles of CTLA-4 in T cell exhaustion.

Conjugated Bilirubin Upregulates TIM-3 Expression on CD4+CD25+ T Cells: Anti-Inflammatory Implications for Hepatitis A Virus Infection

Bilirubin (BR), a metabolite with increased concentrations in plasma during viral hepatitis, has been recognized as a potential immune-modulator. We recently reported that conjugated BR (CB) augments regulatory T cell (Treg) suppressor activity during acute hepatitis A virus (HAV) infection. However, the mechanisms related to the effects of CB on Treg function in the course of hepatotropic viral diseases have not been elucidated. T cell immunoglobulin domain and mucin domain 3 (TIM-3), via its interactions with galectin-9 (GAL-9), is a receptor associated with enhanced Treg function. Thus, TIM-3 expression may be related to the crosstalk between CB and Tregs during HAV infection. Herein, in vitro treatment with high concentrations of CB upregulated TIM-3 expression on Tregs from healthy donors. CB treatment in vitro did not induce de novo Treg generation, and in vitro stimulation with TGF-β, which shows increased secretion during HAV infection, resulted in a trend toward increased TIM-3 expression on Tregs and CD4+ T lymphocytes (TLs) from healthy donors. Interestingly, an upregulation of TIM-3 expression on CD4+CD25+ T cells and an increase in the proportion of CD4+ TLs expressing GAL-9 were found in HAV-infected patients with abnormal CB values relative to healthy controls. In addition, a statistically significantly reduction in IL-17F production was observed after treatment of CD4+ TLs from healthy donors with high doses of CB in vitro. In summary, our results suggest that CB might regulate Treg activity via a TIM-3-mediated mechanism, ultimately leading to an anti-inflammatory hepatoprotective effect.

Programmed Cell Death 1 (PD-1) and Cytotoxic T Lymphocyte-Associated Antigen 4 (CTLA-4) in Viral Hepatitis

Virus-specific cluster of differentiation 8 (CD8+) cytotoxic T cells (CTL) recognize viral antigens presented on major histocompatibility complex (MHC) class I chains on infected hepatocytes, with help from CD4+ T cells. However, this CTL response is frequently weak or undetectable in patients with chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. Programmed cell death 1 (PD-1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) are receptors in the CD28 family of costimulatory molecules, providing inhibitory signals to T cells. The overexpressions of PD-1 and CTLA-4 in patients with viral infection have been shown to associate with functional impairment of virus-specific T cells. In acute viral hepatitis, PD-1 and CTLA-4 are up-regulated during the symptomatic phase, and then down-regulated after recovery. These findings suggest that PD-1 and CTLA-4 have protective effects as inhibitory molecules to suppress cytotoxic T cells which induce harmful destruction of viral infected hepatocytes in self-limited viral hepatitis. In chronic viral hepatitis, the extended upregulations of PD-1 and CTLA-4 are associated with T cell exhaustion and persistent viral infection, suggesting positive correlations between expression of immune inhibitory factors and the chronicity of viral disease. In this review, we summarize recent literature relating to PD-1, CTLA-4, and other inhibitory receptors in antigen-specific T cell exhaustion in viral hepatitis, including hepatitis A, B, C, and others.

Immune mechanisms of idiosyncratic drug-induced liver injury

Idiosyncratic drug reactions (IDRs) continue to be an important issue. Specifically, idiosyncratic drug-induced liver injury (IDILI) is the most likely IDR to lead to drug withdrawal, and it accounts for a significant portion of all cases of acute liver failure. In addition, IDRs are unpredictable and their mechanisms are not well understood. There is increasing clinical evidence that most IDILI is immune mediated. Several immune mediated mechanistic hypotheses exist such as the hapten and danger hypothesis; however, they do not completely explain the idiosyncratic nature of these reactions. Extensive mechanistic studies are needed to better understand these reactions; however, it is impossible to do controlled experiments in humans, and previous animal models did not properly model IDILI. If IDILI is immune mediated and the major factor preventing liver injury in patients is immune tolerance, then a plausible method to develop an animal model of IDILI would be to impair immune tolerance. This hypothesis has shown promise in developing valid animal models of IDILI as demonstrated by a halothane induced liver injury mouse model developed by depleting myeloid derived suppressor cells (MDSCs), as well as an amodiaquine-, isoniazid-and nevirapine-induced liver injury mouse model developed by impairing immune tolerance by blocking PD-1 and CTLA-4, two immune checkpoint inhibitors. Further characterization and validation of these models is required; however, it is likely that they will make it possible to perform mechanistic studies that have been impossible in the past. Relevance for patients: Idiosyncratic drug-induced liver injury can be serious leading to liver transplantation or death. Their idiosyncratic nature makes mechanistic studies very difficult. However, with the development of the first animal model that is similar to the liver injury that occurs in humans, it will be possible to study the mechanisms involved. With a better mechanistic understanding it should be possible to test drug candidates and produce safer drugs. In addition, it should be possible to design better treatments when drug-induced liver injury does occur.

Forsythoside A Inhibits BVDV Replication via TRAF2-Dependent CD28-4-1BB Signaling in Bovine PBMCs

Bovine viral diarrhea virus (BVDV), the causative agent of bovine viral diarrhea/mucosal disease (BVD/MD), is an important pathogen of cattle and other wild animals throughout the world. BVDV infection typically leads to an impaired immune response in cattle. In the present study, we investigated the effect of Forsythoside A (FTA) on BVDV infection of bovine peripheral blood mononuclear cells (PBMCs). We found that Forsythoside A could not only promote proliferation of PBMCs and T cells activation but also inhibit the replication of BVDV as well as apoptosis induced by BVDV. FTA treatment could counteract the BVDV-induced overproduction of IFN-γ to maintain the immune homeostasis in bovine PBMCs. At same time, FTA can enhance the secretion of IL-2. What's more, BVDV promotes the expression of CD28, 4-1BB and TRAF-2, which can be modulated by FTA. Our data suggest that FTA protects PBMCs from BVDV infection possibly via TRAF2-dependent CD28-4-1BB signaling, which may activate PBMCs in response to BVDV infection. Therefore, this aids in the development of an effective adjuvant for vaccines against BVDV and other specific FTA-based therapies for preventing BVDV infection.