BackgroundRadioimmunotherapy has a promising antitumor effect in hepatocellular carcinoma (HCC), depending on the regulatory effect of radiotherapy on tumor immune microenvironment. Ionizing radiation (IR)-induced DNA damage repair (DDR) pathway activation leads to the inhibition of immune microenvironment, thus impairing the antitumor effect of radioimmunotherapy. However, it is unclear whether inhibition of the DDR pathway can enhance the effect of radioimmunotherapy. In this study, we aim to explore the role of DDR inhibitor AZD6738 on the combination of radiotherapy and immune checkpoint inhibitors (ICIs) in HCC.MethodsC57BL/6 mouse subcutaneous tumor model was used to evaluate the ability of different treatment regimens in tumor growth control and tumor recurrence inhibition. Effects of each treatment regimen on the alterations of immunophenotypes including the quantification, activation, proliferating ability, exhaustion marker expression, and memory status were assessed by flow cytometry.ResultsAZD6738 further increased radiotherapy-stimulated CD8+T cell infiltration and activation and reverted the immunosuppressive effect of radiation on the number of Tregs in mice xenografts. Moreover, compared with radioimmunotherapy (radiotherapy plus anti-PD-L1 (Programmed death ligand 1)), the addition of AZD6738 boosted the infiltration, increased cell proliferation, enhanced interferon (IFN)-γ production ability of TIL (tumor-infiltrating lymphocyte) CD8+T cells, and caused a decreasing trend in the number of TIL Tregs and exhausted T cells in mice xenografts. Thus, the tumor immune microenvironment was significantly improved. Meanwhile, triple therapy (AZD6738 plus radiotherapy plus anti-PD-L1) also induced a better immunophenotype than radioimmunotherapy in mice spleens. As a consequence, triple therapy displayed greater benefit in antitumor efficacy and mice survival than radioimmunotherapy. Mechanism study revealed that the synergistic antitumor effect of AZD6738 with radioimmunotherapy relied on the activation of cyclic GMP–AMP synthase /stimulator of interferon genes (cGAS/STING) signaling pathway. Furthermore, triple therapy led to stronger immunologic memory and lasting antitumor immunity than radioimmunotherapy, thus preventing tumor recurrence in mouse models.ConclusionsOur findings indicate that AZD6738 might be a potential synergistic treatment for radioimmunotherapy to control the proliferation of HCC cells, prolong survival, and prevent tumor recurrence in patients with HCC by improving the immune microenvironment.
BackgroundPrevious studies have explored cancer immunotherapy with radiotherapy or anti-angiogenic therapy, but no trials have reported a triple therapy approach. This study aimed to investigate safety and clinical outcome of PD-1/PD-L1 inhibitors combined with palliative radiotherapy and targeted angiogenesis therapy in hepatocellular carcinoma (HCC) of Barcelona Clinic Liver Cancer (BCLC) stage C.MethodsConsecutive patients (n=16) treated with PD-1/PD-L1 inhibitors combined with radiotherapy and anti-angiogenic therapy in a bi-institutional cohort between July 2017 and December 2020 were retrospectively included. Radiotherapy was conducted within 14 days of the first administration of immunotherapy. The primary endpoint was treatment-related adverse event (TRAE).ResultsThe median follow-up was 383 days. Fifteen patients (93.8%) experienced at least 1 TRAE. The most common TRAEs of any grade were rash (25%), diarrhea (25%), aspartate aminotransferase increase (18.8%), alanine transaminase increase (18.8%), decreased appetite (18.8%), and fatigue (18.8%). Grade 3/4 TRAEs occurred in 4 patients (25%) and finally led to treatment interruption. No patient death was attributed to treatment. No specific events were responsible for the addition of radiotherapy. Six patients showed partial response, 7 showed stable disease, and 2 showed progressive disease. The objective response rate and disease control rate were 40.0% (95% CI 16.3%–67.7%) and 86.7% (95% CI 59.5%–98.3%), respectively. Moreover, the median progression-free survival was 140 days. Patients had a median overall survival of 637 days, and the estimated rates of survival at 6 and 12 months were 92.3% and 75.5%, respectively.ConclusionPD-1/PD-L1 inhibitors combined with palliative radiotherapy and anti-angiogenic therapy appear to be safe, with no unexpected adverse events. Additional studies exploring the clinical benefit are warranted.
Background and purpose: Radiotherapy (RT) has a promising anti-tumor effect depending on its effects on both cancer cells and tumor immune microenvironment (TIME). As one of the most common alterations in hepatocellular carcinoma (HCC), wnt/b-catenin pathway activation, has been reported to induce radioresistance and suppressive TIME. In this study, we aim to explore the effect of wnt/b-catenin inhibitor ICG-001 on radiosensitivity and RT-related TIME of HCC and the underlying mechanism. Materials and methods: C57BL/6 and nude mouse tumor models were used to evaluate the efficacy of different treatments on tumor growth, recurrence and mice survival. Flow cytometry was performed to assess tumor infiltrating lymphocytes (TILs). DNA damage response (DDR) and radioresistance was inves-
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