Circulating soluble programmed death-1 levels may differentiate immune-tolerant phase from other phases and hepatocellular carcinoma from other clinical diseases in chronic hepatitis B virus infection

Targeting alternative splicing as a new cancer immunotherapy-phosphorylation of serine arginine-rich splicing factor (SRSF1) by SR protein kinase 1 (SRPK1) regulates alternative splicing of PD1 to generate a soluble antagonistic isoform that prevents T cell exhaustion

BACKGROUND

Regulation of alternative splicing is a new therapeutic approach in cancer. The programmed cell death receptor 1 (PD-1) is an immunoinhibitory receptor expressed on immune cells that binds to its ligands, PD-L1 and PD-L2 expressed by cancer cells forming a dominant immune checkpoint pathway in the tumour microenvironment. Targeting this pathway using blocking antibodies (nivolumab and pembrolizumab) is the mainstay of anti-cancer immunotherapies, restoring the function of exhausted T cells. PD-1 is alternatively spliced to form isoforms that are either transmembrane signalling receptors (flPD1) that mediate T cell death by binding to the ligand, PD-L1 or an alternatively spliced, soluble, variant that lacks the transmembrane domain.

METHODS

We used PCR and western blotting on primary peripheral blood mononuclear cells (PBMCs) and Jurkat T cells, IL-2 ELISA, flow cytometry, co-culture of melanoma and cholangiocarcinoma cells, and bioinformatics analysis and molecular cloning to examine the mechanism of splicing of PD1 and its consequence.

RESULTS

The soluble form of PD-1, generated by skipping exon 3 (∆Ex3PD1), was endogenously expressed in PBMCs and T cells and prevents cancer cell-mediated T cell repression. Multiple binding sites of SRSF1 are adjacent to PD-1 exon 3 splicing sites. Overexpression of phosphomimic SRSF1 resulted in preferential expression of flPD1. Inhibition of SRSF1 phosphorylation both by SRPK1 shRNA knockdown and by a selective inhibitor, SPHINX31, resulted in a switch in splicing to ∆Ex3PD1. Cholangiocarcinoma cell-mediated repression of T cell IL-2 expression was reversed by SPHINX31 (equivalent to pembrolizumab).

CONCLUSIONS

These results indicate that switching of the splicing decision from flPD1 to ∆Ex3PD1 by targeting SRPK1 could represent a potential novel mechanism of immune checkpoint inhibition in cancer.

Navigating through the PD-1/PDL-1 Landscape: A Systematic Review and Meta-Analysis of Clinical Outcomes in Hepatocellular Carcinoma and Their Influence on Immunotherapy and Tumor Microenvironment

This systematic review aimed to assess the prognostic significance of programmed cell death-ligand 1 (PDL-1) and programmed cell death protein 1 (PD-1) in hepatocellular carcinoma (HCC). Medline, EMBASE, and Cochrane Library database searches were conducted, revealing nine relevant cohort studies (seven PDL-1 and three PD-1). Our meta-analysis showed that PD-1/PDL-1 was a marker of poor survival, regardless of the assessment method (PD-1 overall survival (OS): hazard ratio (HR) 2.40; 95% confidence interval (CI), 1.30–4.42; disease-free survival (DFS): HR 2.12; 95% CI, 1.45–3.10; PDL-1: OS: HR 3.61; 95% CI, 2.75–4.75; and DFS: HR 2.74; 95% CI, 2.09–3.59). Additionally, high level of PD-1/PDL-1 expression was associated with aging, multiple tumors, high alpha-fetoprotein levels, and advanced Barcelona Clinic Liver Cancer stage. This high level significantly predicted a poor prognosis for HCC, suggesting that anti-PD-1 therapy is plausible for patients with HCC. Furthermore, HIF-1 induces PD-1 expression, and PD1lowSOCS3high is associated with a better prognosis. Taken together, combination therapy may be the key to effective immunotherapy. Thus, exploring other markers, such as HIF-1 and SOCS3, along with PD-1/PDL-1 immunotherapy, may lead to improved outcomes.

Immune checkpoints on T and NK cells in the context of HBV infection: Landscape, pathophysiology and therapeutic exploitation

In hepatitis B virus (HBV) infection, the interplay between the virus and the host immune system is crucial in determining the pathogenesis of the disease. Patients who fail to mount a sufficient and sustained anti-viral immune response develop chronic hepatitis B (CHB). T cells and natural killer (NK) cells play decisive role in viral clearance, but they are defective in chronic HBV infection. The activation of immune cells is tightly controlled by a combination of activating and inhibitory receptors, called immune checkpoints (ICs), allowing the maintenance of immune homeostasis. Chronic exposure to viral antigens and the subsequent dysregulation of ICs actively contribute to the exhaustion of effector cells and viral persistence. The present review aims to summarize the function of various ICs and their expression in T lymphocytes and NK cells in the course of HBV infection as well as the use of immunotherapeutic strategies targeting ICs in chronic HBV infection.

Serum soluble programmed death-1 levels predict the spontaneous HBeAg seroclearance in chronic hepatitis B

BACKGROUND AND AIMS

In chronic hepatitis B virus (HBV) infection, earlier seroclearance of hepatitis B e antigen (HBeAg) is associated with more favorable outcomes. Soluble programmed cell death 1 (sPD-1) has been implicated in higher viral load and hepatocellular carcinoma. We investigated the association between sPD-1 levels and spontaneous HBeAg seroclearance.

METHODS

Baseline serum samples from 488 HBeAg-seropositive patients in the REVEAL-HBV cohort were tested for sPD-1 levels. Among them, 329 with available follow-up serum samples were further assayed. Multivariate Cox regression analysis was used to estimate the adjusted rate ratio (aRR) and 95% confidence interval (CI) with adjustment of host and viral factors. The 66th percentile and an annual reduction of ≥ 10% were used as the cut-off point for baseline sPD-1 levels (high/low) and sPD-1 trajectory (decline/no decline), respectively.

RESULTS

Lower baseline sPD-1 levels [aRR (95% CI): 2.19 (1.47-3.27)] and long-term decline in sPD-1 levels [aRR (95% CI): 4.08 (2.79-5.97)] were both independent predictors for HBeAg seroclearance. However, further stratification analysis by HBV genotype showed that lower baseline sPD-1 levels were significantly associated with HBeAg seroclearance only in genotype C infection [aRR (95% CI): 4.47 (2.38-8.37)] but not in genotype B infection. On the other hand, long-term decline in sPD-1 levels was predictive for HBeAg seroclearance regardless of HBV genotype with aRR (95% CI) of 4.62 (2.71-7.88) and 2.95 (1.68-5.17), respectively, for genotypes B and C.

CONCLUSION

Serum sPD-1 levels may serve as a novel immunological predictor for spontaneous HBeAg seroclearance in patients with chronic hepatitis B.

The association between sPD-1 levels versus liver biochemistry and viral markers in chronic hepatitis B patients: a comparative study of different sPD-1 assays

BACKGROUND

Soluble programmed death-1 (sPD-1) is a novel immune markers and possibly predictive of chronic hepatitis B (CHB) outcome. However, results were inconsistent by different ELISA kits. This study aims to compare the characteristics and correlations with other markers for sPD-1 measured by MyBioSource (MB) and R&D (RD) kits.

METHODS

A total of 254 untreated CHB patients from three sites were assayed with sPD-1 by MB and RD kits at the same time. Spearman's correlations between the kits, and those with viral markers and ALT levels were calculated. Multivariate linear regression analysis was applied for independent factors associated with the sPD-1 levels.

RESULTS

There's no correlation between sPD-1 level using MB and RD assays. sPD-1 by MB correlated profoundly with HBsAg (r = 0.8311, P < 0.0001), HBV DNA (r = 0.3896, P < 0.0001), and ALT levels (r = 0.1604, P = 0.0105) while an opposite trend by RD kit (r = - 0.0644, P = 0.3109; r = 0.2554, P < 0.0001; r = 0.4417, P < 0.0001, respectively for the 3 markers). In the multivariate linear regression analysis, HBsAg and ALT levels was the major factor associated with sPD-1 levels by MB and RD, respectively.

CONCLUSIONS

The characteristics and correlations with host/viral markers of sPD-1 by the two kits are different and leading to different associations on clinical outcomes of CHB.

Serum soluble programmed cell death 1 levels predict spontaneous functional cure in inactive carriers with chronic hepatitis B

BACKGROUND

Hepatitis B surface antigen (HBsAg) seroclearance is the most important milestone indicating favourable clinical outcomes in patients with chronic hepatitis B (CHB). However, it is difficult to achieve due to the impaired HBV-specific immunity, such as programmed cell death 1 (PD-1)-associated T cell exhaustion. We assessed soluble PD-1 (sPD-1) as a novel seromarker for predicting spontaneous HBsAg loss.

METHODS

Serial serum levels of sPD-1 were evaluated in 1046 untreated hepatitis B e antigen (HBeAg)-seronegative individuals who had achieved undetectable serum HBV DNA. Multiple regression analyses were applied to assess associations among baseline and subsequent sPD-1 levels, HBsAg decline during follow-up, and spontaneous HBsAg seroclearance.

RESULTS

A total of 390 individuals achieved spontaneous HBsAg seroclearance during 6464.4 person-years of follow-up. Baseline sPD-1 levels were inversely associated with baseline HBsAg levels (qHBsAg) as well as a greater decline in qHBsAg during follow-up. Incidence rates of HBsAg seroclearance were 11.5, 61.7, 96.7 and 151.0 per 1000 person-years for sPD-1 levels of ≥4000, 536-3999, 125-535 and <125 pg/mL, respectively (P_trend  < 0.0001). Compared with baseline sPD-1 levels ≥4000 pg/mL, the rate ratio (95% CI) of HBsAg seroclearance was 2.1 (1.1-3.9), 3.0 (1.6-5.5) and 5.1 (2.8-9.5), for baseline sPD-1 levels of 536-3999, 125-535 and <125 pg/mL, respectively, after adjustment for sex, age and serum alanine aminotransferase and HBsAg levels.

CONCLUSION

sPD-1 level is a novel marker which independently predicts spontaneous HBsAg seroclearance of HBeAg-negative inactive CHB patients with undetectable HBV DNA. (word count: 234, <250).

Programmed Cell Death-1 and Its Ligands as Targets for Therapy of Multiple Myeloma Patients

Purpose

Among hematological malignancies, the expression profile of programmed cell death-1 (PD-1) and its ligands in multiple myeloma (MM) is still debated by numerous research groups. In current study, we characterized the expression of PD-1 and its ligands both on RNA and protein levels in MM patients. We have also attempted to analyze whether daratumumab therapy might overcome CD38-mediated immunosuppression that inhibits in particular CD8+ T-cell function.

Patients and Methods

This study included 149 newly diagnosed MM patients and 15 relapsed/refractory MM patients before and after daratumumab treatment. The mRNA levels of PDCD1, PDCD1LG1, PDCD1LG2 and their splicing variants was assessed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Flow cytometry was used to characterize the surface expression of PD-1 and its ligands on plasma cells, B and T cells. The surface expression of PD-1 on T cells was assessed by flow cytometry before and after daratumumab treatment.

Results

The mRNA expression of PDCD1LG1, PDCD1LG2 and their splicing variants were higher in plasma cells as compared to bone marrow mononuclear cells (BMMCs). Our results show that the percentage of plasma cells expressing PD-L1 was significantly higher than plasma cells expressing PD-L2 (p<0.0001) in bone marrow (BM) of MM patients. There was no significant difference between the percentage of plasma cells expressing PD-1 and B cells expressing PD-1 in BM of MM patients (11.19% vs 8.91%). We also found that the percentage of CD8+PD-1+ T cells was significantly higher than CD4+PD-1+T cells in BM (p<0.0001) of MM patients. Here, we observed no change in PD-1 expression on CD4+ and CD8+ T cells after the daratumumab treatment.

Conclusion

The PD-1 and its ligands might represent an interesting target for MM immunotherapy, as one would target both malignant plasma cells as well as the immune cells that play a key role in tumor escape mechanisms.

Soluble programmed cell death-1 predicts hepatocellular carcinoma development during nucleoside analogue treatment

Soluble immune checkpoint molecules are emerging novel mediators of immune regulation. However, it is unclear whether soluble immune checkpoint proteins affect the development of hepatocellular carcinoma (HCC) during nucleos(t)ide analogue (NA) treatment in patients with chronic hepatitis B virus infection. This study included 122 NA-naïve patients who received NA therapy. We assessed the associations of clinical factors, including soluble immune checkpoint proteins, with HCC development during NA treatment. The baseline serum concentrations of 16 soluble immune checkpoint proteins were measured using multiplexed fluorescent bead-based immunoassay. In total, 13 patients developed HCC during the follow-up period (median duration, 4.3 years). Of the 16 proteins, soluble inducible T-cell co-stimulator (≥ 164.71 pg/mL; p = 0.014), soluble programmed cell death-1 (sPD-1) (≤ 447.27 pg/mL; p = 0.031), soluble CD40 (≤ 493.68 pg/mL; p = 0.032), and soluble herpes virus entry mediator (≤ 2470.83 pg/mL; p = 0.038) were significantly associated with HCC development (log-rank test). In multivariate analysis, an sPD-1 level ≤ 447.27 pg/mL (p = 0.014; hazard ratio [HR], 4.537) and α-fetoprotein level ≥ 6.4 ng/mL (p = 0.040; HR, 5.524) were independently and significantly associated with HCC development. Pre-treatment sPD-1 is a novel predictive biomarker for HCC development during NA treatment.

Clinicopathological and Prognostic Value of Programmed Cell Death 1 Expression in Hepatitis B Virus-related Hepatocellular Carcinoma: A Meta-analysis

BACKGROUND AND AIMS

The efficacy of targeted programmed cell death 1/programmed death ligand 1 (PD-1/PD-L1) monoclonal antibodies (mAbs) has been confirmed in many solid malignant tumors. The overexpression of PD-1/PD-L1 serves as a biomarker to predict prognosis and clinical progression. However, the role of PD-1 in patients with hepatitis B virus-related hepatocellular carcinoma (HBV-HCC) remains indeterminate. Given that HBV is the most important cause for HCC, this study aimed to investigate the prognostic and clinicopathological value of PD-1 in HBV-HCC via a meta-analysis.

METHODS

We searched PubMed, Embase, Scopus, the Cochrane Library, Web of Science and Google Scholar up to January 2021 for studies on the correlation between clinicopathology/prognosis and PD-1 in patients with HBV-HCC. The pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated to investigate the prognostic significance of PD-1 expression. The odds ratios (ORs) and 95% CIs were determined to explore the association between PD-1 expression and clinicopathological features.

RESULTS

Our analysis included seven studies with 658 patients, which showed that high PD-1 expression was statistically correlated with poorer overall survival (HR=2.188, 95% CI: [1.262-3.115], p<0.001) and disease-free survival (HR=2.743, 95% CI: [1.980-3.506], p<0.001). PD-1 overexpression was correlated with multiple tumors (OR=2.268, 95% CI: [1.209-4.257], p=0.011), high level of alpha fetoprotein (AFP; OR=1.495, 95% CI: [1.005-2.223], p=0.047) and advanced Barcelona Clinic Liver Cancer (BCLC) stage (OR=3.738, 95% CI: [2.101-6.651], p<0.001).

CONCLUSIONS

Our meta-analysis revealed that the high level of PD-1 expression was associated with multiple tumors, high level of AFP and advanced BCLC stage. It significantly predicted a poor prognosis of HBV-HCC, which suggests that anti-PD-1 therapy for HBV-HCC patients is plausible.

Circulating levels of sPD-1 and PD-1 genetic variants are associated with hepatitis B infection and related liver disease progression

BACKGROUND

Programmed cell death-1 (PD-1) variants and circulating levels of soluble PD-1 are associated with susceptibility to malignant and infectious disease. This study aimed to examine the association of PD-1.5 and PD-1.9 variants, and plasma sPD-1 levels with HBV infection and disease progression.

METHODS

The study cohort consists of HBV-infected adults (n=513) stratified by clinical course, including chronic hepatitis B (CHB, n=173), liver cirrhosis (LC, n=134), hepatocellular carcinoma (HCC, n=206), and matched healthy controls (HC, n=196). The PD-1.5 (rs2227981 C/T) and PD-1.9 (rs2227982 C/T) genetic variants were genotyped by Sanger sequencing, and plasma sPD-1 levels were quantified by enzyme immunoassay.

RESULTS

The plasma sPD-1 levels were significantly high among HBV patients. The highest plasma sPD-1 levels were observed in CHB patients, followed by the LC and HCC groups. In addition, the plasma sPD-1 levels correlated positively with liver inflammation (aspartate transaminase, AST: rho=0.57, P<0.0001 and alanine aminotransferase, ALT: rho=0.57, P<0.0001) and were positively correlated with liver fibrosis (AST to Platelet Ratio Index, APRI score: rho=0.53, P<0.0001). The PD-1.9 TT genotype was less frequent in CHB patients compared to LC, HCC and HCC+LC patients in both codominant and recessive models (P<0.01) and was found to be a risk factor for HCC predisposition [HCC vs. non-HCC: OR=2.0 (95% CI: 1.13-3.7), P_adj=0.017]. The PD-1.5 CT genotype was associated with a reduced risk of acquiring HCC [OR=0.6 (95%CI: 0.4-0.9), P_adj=0.031].

CONCLUSION

Our study concludes that sPD-1 levels are associated with liver inflammation and progression of liver fibrosis and the PD-1.5 and PD-1.9 variants are associated with HBV infection and progression of liver disease.

Prognostic value of soluble programmed cell death-1 (sPD-1) and soluble programmed cell death ligand-1 (sPD-L1) for hepatocellular carcinoma: a systematic review and meta-analysis

BACKGROUND

Preliminary studies have suggested that soluble programmed death-1 (sPD-1) and soluble programmed cell death ligand-1 (sPD-L1) have prognostic implications in many malignant tumors. However, the correlation between sPD-1/sPD-L1 level and prognosis of hepatocellular carcinoma (HCC) is still unclear.

METHODS

We searched several electronic databases from database inception to October 7, 2021. Meta-analyses were performed separately for overall survival (OS), disease-free survival (DFS), recurrence-free survival (RFS), time to progression (TTP), and tumor-free survival (TFS). Random effects were introduced to this meta-analysis. The correlation between sPD-1/sPD-L1 level and prognosis was evaluated using hazard ratios (HRs) with 95% confidence intervals (95%CIs).

RESULTS

A total of 11 studies (1291 patients) were incorporated into this meta-analysis, including seven on sPD-L1, two on sPD-1, and two about both factors. The pooled results showed that high sPD-L1 level was associated with worse OS (HR = 2.46, 95%CI 1.74-3.49, P < 0.001; I² = 31.4, P = 0.177) and poorer DFS/RFS/TTP/TFS of patients with HCC (HR = 2.22, 95%CI 1.47-3.35, P < 0.001; I² = 66.1, P = 0.011), irrespective of method of detection, study type, treatment, cut-off value and follow-up time. In contrast, the level of sPD-1 was not correlated to the OS (HR = 1.19, 95%CI 0.55-2.56, P = 0.657) and DFS/TFS of patients with HCC (HR = 0.94, 95%CI 0.36-2.49, P = 0.906).

CONCLUSION

sPD-L1 rather than sPD-1 could be a good predictor for recurrence and survival after treatment for HCC. More high-quality prospective studies are warranted to assess the prognostic value of sPD-1 or sPD-L1 for HCC.

Evaluation of circulating PD-1 and PD-L1 as diagnostic biomarkers in dogs with tumors

Background

Programmed cell death protein-1 (PD-1) and programmed cell death ligand-1 (PD-L1) have important roles in tumor evasion of the immune system.

Objectives

This study aimed to assess the diagnostic utility of circulating PD-1 and PD-L1 levels in healthy dogs and dogs with tumors.

Methods

Circulating PD-1 and PD-L1 levels in the serum of 71 dogs with tumors were compared with those of 52 healthy dogs by performing enzyme-linked immunosorbent assay (ELISA).

Results

The ELISA results revealed higher circulating PD-1 and PD-L1 levels in dogs with tumors (2.9 [2.2–3.7] ng/mL; median [IQR] and 2.4 [1.4–4.4] ng/mL, respectively) than in healthy dogs (2.4 [1.9–3.0] ng/mL; p = 0.012 and 1.4 [0.9–2.1] ng/mL; p < 0.001, respectively). Especially, there was a significant difference in circulating PD-1 levels between healthy dogs and dogs with malignant epithelial tumors (2.4 [1.9–3.0] ng/mL and 3.1 [2.6–4.4] ng/mL, respectively; p < 0.01). In addition, there was a significant difference in circulating PD-L1 levels between healthy dogs and dogs with lymphomas (1.4 [0.9–2.1] ng/mL and 2.7 [1.6–5.8] ng/mL, respectively; p < 0.001).

Conclusion

This study indicates that circulating PD-1 and PD-L1 have potential as tumor diagnostic biomarkers in dogs with tumors.

Soluble B7-CD28 Family Inhibitory Immune Checkpoint Proteins and Anti-Cancer Immunotherapy

Co-inhibitory B7-CD28 family member proteins negatively regulate T cell responses and are extensively involved in tumor immune evasion. Blockade of classical CTLA-4 (cytotoxic T lymphocyte-associated antigen-4) and PD-1 (programmed cell death protein-1) checkpoint pathways have become the cornerstone of anti-cancer immunotherapy. New inhibitory checkpoint proteins such as B7-H3, B7-H4, and BTLA (B and T lymphocyte attenuator) are being discovered and investigated for their potential in anti-cancer immunotherapy. In addition, soluble forms of these molecules also exist in sera of healthy individuals and elevated levels are found in chronic infections, autoimmune diseases, and cancers. Soluble forms are generated by proteolytic shedding or alternative splicing. Elevated circulating levels of these inhibitory soluble checkpoint molecules in cancer have been correlated with advance stage, metastatic status, and prognosis which underscore their broader involvement in immune regulation. In addition to their potential as biomarker, understanding their mechanism of production, biological activity, and pathological interactions may also pave the way for their clinical use as a therapeutic target. Here we review these aspects of soluble checkpoint molecules and elucidate on their potential for anti-cancer immunotherapy.

Soluble PD-1: Predictive, Prognostic, and Therapeutic Value for Cancer Immunotherapy

Programmed death protein 1 (PD-1) interaction with PD-L1 deliver immunosuppressive environment for tumor growth, and its blockade with directed monoclonal antibodies (anti-PD-1/anti-PD-L1) has shown remarkable clinical outcome. Lately, their soluble counterparts, sPD-1 and sPD-L1, have been detected in plasma, and elevated levels have been associated with advanced disease, clinical stages, and worst prognosis for cancer patients. Elevated plasma levels of sPD-L1 have been correlated with worst prognosis in several studies and has displayed a persistent outlook. On the other hand, sPD-1 levels have been inconsistent in their predictive and prognostic ability. Pretherapeutic higher sPD-1 plasma levels have shown to predict advanced disease state and to a lesser extent worst prognosis. Any increase in sPD-1 plasma level post therapeutically have been correlated with improved survival for various cancers. In vitro and in vivo studies have shown sPD-1 ability to bind PD-L1 and PD-L2 and block PD-1/PD-L1 interaction. Local delivery of sPD-1 in cancer tumor microenvironment through local gene therapy have demonstrated an increase in tumor specific CD8+ T cell immunity and tumor growth reduction. It had also exhibited enhancement of T cell immunity induced by vaccination and other gene therapeutic agents. Furthermore, it may also lessen the inhibitory effect of circulating sPD-L1 and enhance the effects of mAb-based immunotherapy. In this review, we highlight various aspects of sPD-1 role in cancer prediction, prognosis, and anti-cancer immunity, as well as, its therapeutic value for local gene therapy or systemic immunotherapy in blocking the PD-1 and PD-L1 checkpoint interactions.

Prognostic and clinicopathological significance of PD-1 expression in hepatocellular carcinoma: a meta-analysis

Objective

We performed a meta-analysis to evaluate the prognostic and clinicopathological significance of programmed cell death-1 (PD-1) expression in patients with hepatocellular carcinoma (HCC).

Methods

We searched the Wanfang, Chinese Biomedical Literature, CNKI, PubMed, Embase, and Web of Science databases for relevant articles from inception to 1 July 2020. Statistical analysis was performed using RevMan 5.3 (Cochrane, London, UK) and Stata 14.0 software (StataCorp LP, College Station, TX, USA).

Results

Eight studies involving 732 patients with HCC were included. Higher expression of PD-1 predicted longer disease-free survival [hazard ratio (HR) 0.53, 95% confidence interval (CI): 0.38–0.72]. No significant correlation was observed between PD-1 expression and overall survival (HR 0.89, 95% CI: 0.58–1.35). PD-1 expression was correlated with age [odds ratio (OR) 0.66, 95% CI: 0.46–0.94] and alpha-fetoprotein level (OR 2.27, 95% CI: 1.45–3.55); no correlation was observed with sex, tumor size, tumor metastasis, hepatitis B virus history, tumor stage, or tumor multiplicity. Sensitivity analysis demonstrated no excessive effect on stability of the pooled results. No significant publication bias was found among the identified studies.

Conclusion

PD-1 overexpression predicted better disease-free survival in patients with HCC. Moreover, PD-1 expression was associated with age and alpha-fetoprotein level.

Clinicopathological and Prognostic Roles of the Expression Levels of the Programmed Cell Death-1 Gene in Patients with Hepatocellular Carcinoma: A Systematic Review and Meta-Analysis

Background: Multiple studies have explored the prognostic role and clinical significance of the expression of the programmed cell death-1 (PD-1) gene in hepatocellular carcinoma (HCC). However, the results have been inconsistent. This study evaluated PD-1 expression and its clinical significance in patients with HCC, as well as the correlation between HCC pathological features and prognoses. Methods: All related research in PubMed, Embase, and Web of Science prior to October 31, 2019, was retrieved. The Newcastle-Ottawa Scale was used to evaluate the quality of the literature. Stata 14.0 statistical software was used to analyze the data, and the correlations between PD-1 expression and the clinicopathological characteristics of patients were analyzed using the odds ratio (OR) and its 95% confidence interval (CI). The hazard ratio (HR) and its 95% CI were used to analyze the correlation between PD-1 high expression and patient prognosis. Begg's test was used to evaluate publication bias. Results: A total of 581 patients were analyzed in the six studies included in the meta-analysis. Pooled analysis revealed that high levels of PD-1 expression did not correlate with overall survival (HR = 0.79; 95% CI: [0.41-1.54]; p = 0.493). PD-1 positivity was associated with better disease-free survival (HR = 0.52; 95% CI: [0.38-0.72]; p < 0.0001). Furthermore, elevated PD-1 expression corrected for age (OR = 0.62, 95% CI: [0.41-0.96]; p = 0.030) and alpha-fetoprotein levels (OR = 2.27, 95% CI: [1.46-3.55]; p < 0.0001), were not correlated with patient sex, tumor size, tumor multiplicity, hepatitis B virus history, tumor node metastasis stage or Barcelona Clinic Liver Cancer stage. Conclusions: This meta-analysis revealed that PD-1 expression may be a useful prognostic marker in HCC patients. Prospective clinical studies are needed to support these findings.

Profiles of serum soluble programmed death-1 and programmed death-ligand 1 levels in chronic hepatitis B virus-infected patients with different disease phases and after anti-viral treatment

BACKGROUND

Soluble programmed death-1 (sPD-1) and soluble programmed death-ligand 1 (sPD-L1) play a role in immune regulation of chronic hepatitis B virus (HBV) infection.

AIM

To investigate the profiles of serum sPD-1 and sPD-L1 in chronic HBV-infected patients with different disease phases and after anti-viral treatment.

METHODS

A total of 99 chronic HBV-infected patients were enrolled and divided into HBeAg-positive chronic HBV infection (EPI) group, HBeAg-positive chronic hepatitis B (EPH) group, HBeAg-negative chronic hepatitis B (ENH) group and HBeAg-negative chronic HBV infection (ENI) group. Eleven healthy subjects were included as healthy controls (HCs). Thirty-two EPH patients received anti-viral treatment with nucleos(t)ide analogues and were followed up to 5 years. Serum sPD-1 and sPD-L1 levels were detected by Multiplex Immunoassays.

RESULTS

Serum sPD-1 and sPD-L1 levels of chronic HBV infected patients were significantly higher than that of HCs (P < 0.01). Patients in EPH, ENH and EPI groups had higher serum sPD-1 and sPD-L1 levels than that in HCs (P < 0.01). After anti-viral treatment, serum sPD-1 and sPD-L1 levels declined rapidly. EPH patients with HBeAg clearance after 2 years of anti-viral treatment showed lower baseline HBeAg and sPD-1 levels compared to those without HBeAg clearance.

CONCLUSIONS

Serum sPD-1 and sPD-L1 levels varied among chronic HBV infected patients with different disease phases. Lower baseline sPD-1 levels were associated with HBeAg clearance after 2 years of anti-viral treatment in EPH patients.

Preliminary observations on soluble programmed cell death protein-1 as a prognostic and predictive biomarker in patients with metastatic melanoma treated with patient-specific autologous vaccines

Because of its role as an immune checkpoint, levels of soluble programmed cell death protein-1 (sPD-1) could be useful as a prognostic biomarker or predictive biomarker in cancer patients treated with vaccines. Very low levels of sPD-1 may indicate lack of an existing anti-cancer immune response; very high levels may indicate an active immune response that is suppressed. In between these extremes, a decrease in PD-1 following injections of an anti-cancer vaccine may indicate an enhanced immune response that has not been suppressed. Blood samples obtained during a randomized trial in patients with metastatic melanoma were tested from 22 patients treated with a tumor cell vaccine (TCV) and 17 treated with a dendritic cell vaccine (DCV). Survival was better in DCV-treated patients. sPD-1 was measured at week-0, one week before the first of three weekly subcutaneous injections, and at week-4, one week after the third injection. The combination of a very low baseline sPD-1, or absence of a very high PD-1 at baseline followed by a decline in sPD-1 at week-4, was predictive of surviving three or more years in DCV-treated patients, but not TCV-treated. Among DCV-treated patients, these sPD-1 criteria appropriately classified 8/10 (80%) of 3-year survivors, and 6/7 (86%) of patients who did not survive three years. These preliminary observations suggest that sPD-1 might be a useful biomarker for melanoma patients being considered for treatment with this DCV vaccine, and/or to predict efficacy after only three injections, but this would have to be confirmed in larger studies.

Soluble programmed death-1 is a useful indicator for inflammatory and fibrosis severity in chronic hepatitis B

Elevated programmed death-1 (PD-1) has been found in immune cells in viral infections and plays an important role in infection persistence. The soluble form of PD-1 (sPD-1) is involved in tumours and viral infections. The aim of this study was to investigate the role of sPD-1 in chronic hepatitis B (CHB). A total of two hundred and eighteen CHB patients and sixty healthy controls (HC) were enrolled. Demographic data and clinical parameters were collected. An ELISA assay was used to measure serum sPD-1 levels, and the relationships between sPD-1 and clinical/virological characteristics was analysed. sPD-1 levels in CHB patients were higher (median 4.409 IQR 3.435-5.306 pg/mL) than those of HC individuals (median 0.3665 IQR 0.2425-0.5010 pg/mL). Among patients at various disease stages, patients with immune activity showed the highest sPD-1 levels (median 5.138 IQR 4.329-5.406 pg/mL). sPD-1 concentration was associated with HBV markers (HBsAg, HBV DNA and HBeAg) and biochemical parameters (serum aspartate aminotransferase [AST], alanine aminotransferase [ALT], total bilirubin [TBil] and gamma glutamyl transferase [γ-GT] levels) (all P < 0.05). sPD-1 levels were higher in CHB patients with moderate-to-severe inflammation or fibrosis than in those with mild inflammation or fibrosis, regardless of ALT levels. The association between sPD-1 and disease progression of CHB suggests that sPD-1 could serve as a new indicator in assessing liver fibrosis. These findings may further aid in determining the initiation of antiviral treatment in patients with normal ALT levels.

PRDM1 levels are associated with clinical diseases in chronic HBV infection and survival of patients with HBV-related hepatocellular carcinoma

PR domain zinc finger protein 1 (PRDM1)/B lymphocyte-induced maturation protein 1 (BLIMP1) is a transcriptional repressor involved in B and T cell responses which are implicated in chronic hepatitis B virus (HBV) infection and hepatocellular carcinoma (HCC). This study investigated the association of PRDM1 with clinical diseases of chronic HBV infection and prognosis of HBV -related HCC patients. Serum PRDM1 levels were determined in 403 patients with chronic HBV infection (171 chronic hepatitis, 119 cirrhosis and 113 HCC), 70 HBV infection resolvers and 96 healthy control individuals. The PRDM1 levels were analyzed with regard to clinical diseases and overall survival of HCC patients. Serum PRDM1 concentrations in patients with chronic HBV infection were significantly elevated compared with infection resolvers and healthy controls. HBV-related HCC patients had the most significantly elevated PRDM1 levels. PRDM1 levels could considerably differentiate HCC from chronic hepatitis [area under receiver operating characteristic curve (AUC) 0.889, p < 0.001] or cirrhosis (AUC 0.910, p < 0.001). HCC patients with high PRDM1 levels had a poor prognosis (>300 pg/mL vs. ≤300 pg/mL, p = 0.001). High PRDM1 levels were independently associated with increased mortality in HCC patients (hazard ratio 2.997, 95% confidence interval 1.103-4.722, p = 0.003). Overall, this study demonstrated that PRDM1 levels are associated with the clinical diseases of chronic HBV infection. Highly elevated PRDM1 levels are discriminative of HCC from other clinical diseases and indicative of a poor prognosis of HCC patients. The potential association of PRDM1 levels with disease progression and treatment response warrants further investigation.

Immune Checkpoint Inhibitors in Hepatocellular Carcinoma: Opportunities and Challenges

Hepatocellular carcinoma (HCC) is the most common malignancy worldwide, and is especially common in China. A total of 70%-80% of patients are diagnosed at an advanced stage and can receive only palliative care. Sorafenib has been the standard of care for a decade, and promising results for regorafenib as a second-line and lenvatinib as a first-line treatment were reported only 1 or 2 years ago. FOLFOX4 was recently recommended as a clinical practice guideline by the China Food and Drug Administration. All approved systemic therapies remain unsatisfactory, with limited objective response rates and poor overall survival. Immune checkpoint inhibitors (CPIs) offer great promise in the treatment of a rapidly expanding spectrum of solid tumors. Immune checkpoint molecules are involved in almost the whole process of viral-related hepatitis with cirrhosis and HCC and in the most important resistance mechanism of sorafenib. The approval of nivolumab by the U.S. Food and Drug Administration on September 23, 2017, for the treatment of patients with HCC, based only on a phase I/II clinical trial, is a strong hint that immunotherapy will introduce a new era of HCC therapy. CPI-based strategies will soon be a main approach in anticancer treatment for HCC, and we will observe the rapid advances in the therapeutic use of CPIs, even in an adjuvant setting, with great interest. How shall we face the opportunities and challenges? Can we dramatically improve the prognosis of patients with HCC? This review may provide some informed guidance. IMPLICATIONS FOR PRACTICE: Immune checkpoint molecules are involved in almost the whole process of viral-related hepatitis with cirrhosis and hepatocellular carcinoma (HCC) and in the most important resistance mechanism of sorafenib. As all approved systemic therapies in HCC remain unsatisfactory, checkpoint inhibitor (CPI)-based strategies will soon be a main approach in anticancer treatment for advanced stage of HCC, even in an adjuvant setting. In virus-related HCC, especially hepatitis B virus-related HCC, whether CPIs can control virus relapse should be further investigated. Combination strategies involving conventional therapies and immunotherapies are needed to increase clinical benefit and minimize adverse toxicities with regard to the underlying liver disease.

Highly elevated soluble Tim-3 levels correlate with increased hepatocellular carcinoma risk and poor survival of hepatocellular carcinoma patients in chronic hepatitis B virus infection

Background and objective

Upregulated T-cell immunoglobulin and mucin domain containing molecule-3 (Tim-3) in hepatitis B virus (HBV)-specific CD8⁺ T-cells contributes to CD8⁺ T-cell exhaustion during chronic HBV infection. The membrane-bound Tim-3 can be cleaved from the cell surface by sheddase, yielding soluble Tim-3 (sTim-3). This study investigated serum sTim-3 levels in patients with chronic HBV infection of various liver diseases.

Methods

Serum sTim-3 levels were quantitatively determined in 288 patients with chronic HBV infection of various liver diseases. The sTim-3 levels were analyzed in relation to liver diseases including HBV-related hepatocellular carcinoma (HCC) and overall survival of HCC patients.

Results

Serum sTim-3 levels in the patients with chronic HBV infection were significantly elevated compared with healthy controls (P<0.001) and the levels from asymptomatic HBV carrier status, chronic hepatitis, liver cirrhosis to HCC were progressively increased. Serum sTim-3 levels were closely associated with the severity of liver function abnormalities. Importantly, serum sTim-3 levels were independently associated with HCC risk (OR, 4.310; 95% CI, 2.141–8.676, P<0.001) in comparison to non-HCC diseases in chronic HBV infection and significantly associated with the overall survival of HCC patients, with a level >3000 pg/mL being related to shorter overall survival than a level ≤3000 pg/mL (P=0.019).

Conclusion

Serum sTim-3 is involved in disease progression and HCC development in chronic HBV infection and its quantitative determination may be potentially used as a marker for monitoring the disease progression and predicting the HCC prognosis in chronic HBV infection.

[Soluble PD-1 over-expression enhances the anti-tumor effect of senescence tumor cell vaccine against breast cancer cell growth in tumor-bearing mice]

OBJECTIVE

To investigate whether soluble PD-1 overexpression in 4T1 senescence tumor cells enhances the antitumor effect of senescence tumor cell vaccine (STCV) against breast tumor cells in a tumor-bearing mouse model.

METHODS

4T1 cells were treated with interferon-γ (IFN-γ) and the expression of PD-L1 was detected by flow cytometry. CCK8 assay was used to compare the cell proliferation activity between 4T1 cells and 4T1 cells infected by a lentiviral vector of sPD-1 (4T1/sPD-1 cells), and the expressions of sPD-1 mRNA and protein in 4T1/sPD-1 cells were detected using qPCR and Western blotting. The culture supernatant of 4T1/sPD-1 cells was added in 4T1 cells pre-treated with IFN-γ, and PD-1-positive 4T1 cells were detected with flow cytometry. Senescence β-galactosidase staining kit was used to detect the senescent 4T1 and 4T1/sPD-1 cells following exposure to X-ray radiation and Veliparib. Balb/c mice bearing subcutaneous 4T1 tumor xenografts were treated with injections of PBS, 4T1 STCV, or 4T1/sPD-1 STCV, and tumor growth was observed.

RESULTS

Stimulation with IFN-γ concentration-dependently up-regulated PD-L1 expression by as much as (84.80 ± 1.03)% in 4T1 cells (P < 0.001). sPD-1 overexpression in 4T1 cells did not significantly affect the cell proliferation. Treatment of 4T1 cells with 4T1/sPD-1 cell culture supernatant significantly increased the proportion of PD-1 + cells from (6.893 ± 0.271)% to (55.450 ± 0.555)% (P < 0.001). X-ray irradiation combined with Veliparib caused obvious senescence in 4T1 and 4T1/sPD-1 cells. In the tumor-preventing experiment, tumor formation occurred in all the mice in PBS group; 28.787% of the mice in 4T1 STCV group and 55.556% in 4T1/sPD-1 STCV group showed no tumor formation. In the tumor treatment experiment, tumor formation occurred in all the mice in PBS groups while in 4T1 STCV and 4T1/sPD-1 STCV groups, 11.111% and 38.89% of the mice were tumor-free during the observation period, respectively.

CONCLUSIONS

Senescence tumor cells vaccine has antitumor effect against breast cancer in mice, and sPD-1 overexpression can enhance this effect of the vaccine.

PD-1 immunobiology in autoimmune hepatitis and hepatocellular carcinoma

Disruption of liver immune tolerance allows for the development of autoimmune hepatitis (AIH) and hepatocellular carcinoma (HCC). AIH rarely progresses to HCC but the diseases similarly induce the production of IL-18 and matrix metalloproteinases. These molecules have distinct effects on the immune response, including the programmed cell-death 1 (PD-1) axis. In this review, differences in PD-1 function and possible cell signals in AIH and HCC are highlighted.