ObjectiveTherapy-induced tumour microenvironment (TME) remodelling poses a major hurdle for cancer cure. As the majority of patients with hepatocellular carcinoma (HCC) exhibits primary or acquired resistance to antiprogrammed cell death (ligand)-1 (anti-PD-[L]1) therapies, we aimed to investigate the mechanisms underlying tumour adaptation to immune-checkpoint targeting.DesignTwo immunotherapy-resistant HCC models were generated by serial orthotopic implantation of HCC cells through anti-PD-L1-treated syngeneic, immunocompetent mice and interrogated by single-cell RNA sequencing (scRNA-seq), genomic and immune profiling. Key signalling pathway was investigated by lentiviral-mediated knockdown and pharmacological inhibition, and further verified by scRNA-seq analysis of HCC tumour biopsies from a phase II trial of pembrolizumab (NCT03419481).ResultsAnti-PD-L1-resistant tumours grew >10-fold larger than parental tumours in immunocompetent but not immunocompromised mice without overt genetic changes, which were accompanied by intratumoral accumulation of myeloid-derived suppressor cells (MDSC), cytotoxic to exhausted CD8+T cell conversion and exclusion. Mechanistically, tumour cell-intrinsic upregulation of peroxisome proliferator-activated receptor-gamma (PPARγ) transcriptionally activated vascular endothelial growth factor-A (VEGF-A) production to drive MDSC expansion and CD8+T cell dysfunction. A selective PPARγ antagonist triggered an immune suppressive-to-stimulatory TME conversion and resensitised tumours to anti-PD-L1 therapy in orthotopic and spontaneous HCC models. Importantly, 40% (6/15) of patients with HCC resistant to pembrolizumab exhibited tumorous PPARγ induction. Moreover, higher baseline PPARγ expression was associated with poorer survival of anti-PD-(L)1-treated patients in multiple cancer types.ConclusionWe uncover an adaptive transcriptional programme by which tumour cells evade immune-checkpoint targeting via PPARγ/VEGF-A-mediated TME immunosuppression, thus providing a strategy for counteracting immunotherapeutic resistance in HCC.
Background & aims Immune checkpoint blockade (ICB) has been approved for treatment of hepatocellular carcinoma (HCC). However, many patients with advanced HCC are non-responders to ICB monotherapy. Cytotoxic chemotherapy has been proposed to modulate the tumor microenvironment (TME) and sensitize tumors to ICB. Thus, we aimed to study the combination of cytotoxic chemotherapy and ICB in an orthotopic HCC model. Methods Preclinical orthotopic HCC mouse models were used to elucidate the efficacy of 5-fluorouracil (5-FU) and ICB. The mice were intrahepatically injected with RIL-175 or Hepa1-6 cells, followed by treatment with 5-FU and anti-programmed cell death ligand 1 (PD-L1) antibody. Myeloid-derived suppressor cells (MDSCs) were depleted to validate their role in attenuating sensitivity to immunotherapy. Flow cytometry-based immune profiling and immunofluorescence staining were performed in mice and patient samples, respectively. Results 5-FU could induce intratumoral MDSC accumulation to counteract the infiltration of T lymphocytes and natural killer cells, thus abrogating the anti-tumor efficacy of PD-L1 blockade. In clinical samples, MDSCs accumulated and CD8 + T cell numbers decreased following transarterial chemoembolization. Conclusion 5-FU can trigger the accumulation of immunosuppressive MDSCs, impairing the response to PD-L1 blockade in HCC. Our data suggest that the combination of specific chemotherapy and ICB may impair anti-tumor immune responses, warranting further study in preclinical models and consideration in clinical settings. Lay summary Our findings suggest that some chemotherapies may impair the anti-tumor efficacy of immunotherapy. Further studies are required to uncover the specific effects of different chemotherapies on the immunological profile of tumors. This data will be critical for the rational design of combination immunotherapy strategies for patients with hepatocellular carcinoma.
A phthalaldehyde-substituted phthalocyanine has been synthesized that can conjugate with a range of biomolecules, including peptides, monosaccharides, lipids, and DNAs, and be immobilized on the surface of bovine serum album nanoparticles and glass slides using the versatile and efficient phthalaldehyde-amine capture reactions. The light-induced cytotoxic effects of the latter two materials have also been examined against cancer cells and bacteria, respectively, showing that they are highly efficient photosensitizing systems for photodynamic therapy.
Introduction: Intrinsic immunologic composition in liver tumor microenvironment (TME) may play a role in the heterogenous response towards immune-checkpoint blockade in hepatocellular carcinoma (HCC). In some cancers, it has been shown that cytotoxic chemotherapy is synergistic with checkpoint inhibitors. In this study, we evaluated the efficacy and immunomodulation of 5-FU and anti-PD-L1 in orthotopic liver cancer mouse model. Method: The orthotopic mouse model was established with the murine HCC cell line RIL-175 through intrahepatic injection. The tumor-bearing mice was then treated with 5-FU (i.p.) 3 times per week at 20mg/kg. Anti-PD-L1(10mg/kg) was delivered (i.p.) every 5 days. Tumor growth was reflected by the luciferase intensity via in vivo imaging. Upon sacrifice, the tumor tissue, liver, spleen and blood sample were harvested, followed by subsequent immune profiling analysis using flow cytometry. Results: Based on the tumor growth rate and endpoint tumor weight, anti-PD-L1 monotherapy induced a significant tumor reduction whereas 5-FU, either alone or combined with anti-PD-L1, did not have therapeutic effect as compared to vehicle control. Proportions of immunosurveillance cells including natural killer (NK) cells, CD8+ T cells and CD4+ T cells were drastically increased in the tumor site after anti-PD-L1 single treatment, but reduced in 5-FU-treated tumor. To depict the underlying regulation by chemotherapy, immunosuppressive components were also examined. Accumulation in myeloid cells, particularly CD11b+Gr-1+Ly6G+Ly6Cint polymorphonuclear myeloid-derived suppressor cells (P-MDSCs) were found to be a contributing factor to lymphocytes depletion when treated with 5-FU, hence counteracting the anti-tumor activity by PD-L1 blockade. Conclusion: In summary, our data indicate that chemotherapeutics may impose immunosuppressive modulation in HCC TME and latently alter the therapeutic outcome against immune-checkpoint blockade. This study suggests that combination of chemotherapy with checkpoint inhibitors may not be a feasible approach for HCC. Acknowledgement: The study is supported by the Terry Fox Foundation. Key Words: Tumor microenvironment (TME), Hepatocellular carcinoma, Chemotherapy, myeloid-derived suppressor cell (MDSC), anti-PD-L1, immunotherapy Citation Format: Tsz Tung Kwong, Chi Hang Wong, Jing Ying Zhou, Alfred Sze Lok Cheng, Anthony Wing Hung Chan, Stephen Lam Chan. Adverse immunomodulatory effects of chemotherapy on myeloid-derived suppressor cell compromise immune-checkpoint blockade efficacy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 954.
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