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Preferential Expression of Programmed Death Ligand 1 Protein in Tumor-Associated Macrophages and Its Potential Role in Immunotherapy for Hepatocellular Carcinoma.

ABSTRACT: A predictive biomarker of immune checkpoint inhibitor (ICI)-based treatments in hepatocellular carcinoma (HCC) has not been clearly demonstrated. In this study, we focused on the infiltration and programmed death ligand 1 (PD-L1) expression of tumor-associated macrophages (TAMs) in the tumor microenvironment of HCC. Immunohistochemistry demonstrated that PD-L1 was preferentially expressed on CD68⁺ macrophages in the tumor microenvironment of HCC, suggestive of its expression in TAMs rather than in T cells or tumor cells (P < 0.05). A co-culture experiment using activated T cells and M2 macrophages confirmed a significant increase in T cell functionality after the pretreatment of M2 macrophages with anti-PD-L1. Syngeneic mouse model experiments demonstrated that TAMs expressed PD-L1 and tumors treated with anti-PD-L1 showed smaller diameters than those treated with IgG. In these mice, anti-PD-L1 treatment increased activation markers in intratumoral CD8⁺ T cells and reduced the size of the TAM population. Regarding nivolumab-treated patients, three of eight patients responded to the anti-PD-1 treatment. The percentage of Ki-67-positive CD4⁺ and CD8⁺ T cells was higher in responders than non-responders after nivolumab. Overall, PD-L1 expression on TAMs may be targeted by immune-based HCC treatment, and ICI treatment results in the reinvigoration of exhausted CD8⁺ T cells in HCC.

SUBMITTER: Park DJ

PROVIDER: S-EPMC8124544 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:IntroductionProgrammed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) signaling blockade is the most effective strategy for the treatment of immune evading hepatocellular carcinoma (HCC). While immune checkpoint inhibitor has revolutionized the concept of cancer treatment, it has also led to unexpected tumor growth. Regulatory T cells express PD-1 and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) receptors, which are proliferated and activated by antibody binding, and their ratio to CD8+ T cells is altered, which is one of the causes for hyper progressive disease (HPD). We examined the frequency of HPD in anti-PD-1/PD-L1 monotherapy and combination therapy with vascular endothelial growth factor (VEGF) antibody and anti-CTLA-4 antibodies.MethodsThis was a prospective and retrospective cohort study which enrolled 198 patients with unresectable HCC from January 2015 to December 2021 at the Kindai University Hospital. Fifty-eight patients received anti-PD-1/PD-L1 monotherapy, 119 patients combination with VEGF antibody, and 21 patients combination with anti-CTLA-4 antibody. We defined HPD as tumor growth rate (TGR) ratio ≥4, ΔTGR ≥40%, and tumor growth kinetics ratio ≥4.ResultsThe HPD rate was 10.3% (6/58) in anti-PD-1/PD-L1 monotherapy, 1.7% (2/119) in combination with VEGF antibody, and 4.8% (1/21) in combination with anti-CTLA-4 antibody (p = 0.034). The odds ratio for HPD in the combined anti-CTLA-4 antibody group was 0.433 (95% confidence interval [CI]: 0.05-3.83) when compared to the anti-PD-1/PD-L1 monotherapy group and 2.93 (95% CI: 0.25-33.79) when compared to the combined VEGF antibody group.ConclusionThe frequency of HPD in unresectable HCC compared to anti-PD-1/PD-L1 monotherapy was decreased with the combination with anti-VEGF antibody and not increased with anti-CTLA-4 antibody. Anti-PD-1/PD-L1 combined with anti-CTLA-4 antibody is now available in real-world and needs to be further validated with accumulated clinical practice.

Project description:UNLABELLED:Sorafenib, a broad tyrosine kinase inhibitor, is the only approved systemic therapy for advanced hepatocellular carcinoma (HCC) but provides limited survival benefits. Recently, immunotherapy has emerged as a promising treatment strategy, but its role remains unclear in HCCs, which are associated with decreased cytotoxic CD8(+) T-lymphocyte infiltration in both murine and human tumors. Moreover, in mouse models after sorafenib treatment intratumoral hypoxia is increased and may fuel evasive resistance. Using orthotopic HCC models, we now show that increased hypoxia after sorafenib treatment promotes immunosuppression, characterized by increased intratumoral expression of the immune checkpoint inhibitor programmed death ligand-1 and accumulation of T-regulatory cells and M2-type macrophages. We also show that the recruitment of immunosuppressive cells is mediated in part by hypoxia-induced up-regulation of stromal cell-derived 1 alpha. Inhibition of the stromal cell-derived 1 alpha receptor (C-X-C receptor type 4 or CXCR4) using AMD3100 prevented the polarization toward an immunosuppressive microenvironment after sorafenib treatment, inhibited tumor growth, reduced lung metastasis, and improved survival. However, the combination of AMD3100 and sorafenib did not significantly change cytotoxic CD8(+) T-lymphocyte infiltration into HCC tumors and did not modify their activation status. In separate experiments, antibody blockade of the programmed death ligand-1 receptor programmed death receptor-1 (PD-1) showed antitumor effects in treatment-naive tumors in orthotopic (grafted and genetically engineered) models of HCC. However, anti-PD-1 antibody treatment had additional antitumor activity only when combined with sorafenib and AMD3100 and not when combined with sorafenib alone. CONCLUSION:Anti-PD-1 treatment can boost antitumor immune responses in HCC models; when used in combination with sorafenib, anti-PD-1 immunotherapy shows efficacy only with concomitant targeting of the hypoxic and immunosuppressive microenvironment with agents such as CXCR4 inhibitors.

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Preferential Expression of Programmed Death Ligand 1 Protein in Tumor-Associated Macrophages and Its Potential Role in Immunotherapy for Hepatocellular Carcinoma.

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