Supplementary Material for: Exploring Markers of Exhausted CD8 T Cells to Predict Response to Immune Checkpoint Inhibitor Therapy for Hepatocellular Carcinoma

Background: Reversal of CD8 T-cell exhaustion was considered a major antitumor mechanism of anti-programmed cell death-1 (PD-1)/ anti-programmed death ligand-1 (PD-L1)-based immune checkpoint inhibitor (ICI) therapy. Objectives: The aim of this study was to identify markers of T-cell exhaustion that is best associated with ICI treatment efficacy for advanced hepatocellular carcinoma (HCC). Methods: Immune cell composition of archival tumor samples was analyzed by transcriptomic analysis and multiplex immunofluorescence staining. Results: HCC patients with objective response after anti-PD-1/anti-PD-L1-based ICI therapy (n = 42) had higher expression of genes related to T-cell exhaustion. A 9-gene signature (LAG3, CD244, CCL5, CXCL9, CXCL13, MSR1, CSF3R, CYBB, and KLRK1) was defined, whose expression was higher in patients with response to ICI therapy, correlated with density of CD8+LAG3+ cells in tumor microenvironment, and independently predicted better progression-free and overall survival. This 9-gene signature had similar predictive values for patients who received single-agent or combination ICI therapy and was not associated with prognosis in HCC patients who received surgery, suggesting that it may outperform other T-cell signatures for predicting efficacy of ICI therapy for HCC. For HCC patients who underwent surgery for both the primary liver and metastatic lung tumors (n = 31), lung metastatic HCC was associated with a higher exhausted CD8 T-cell signature, consistent with prior observation that patients with lung metastatic HCC may have higher probability of response to ICI therapy. Conclusions: CD8 T-cell exhaustion in tumor microenvironment may predict better efficacy of ICI therapy for HCC.

研究背景：逆转CD8 T细胞耗竭（CD8 T-cell exhaustion）被认为是基于抗程序性细胞死亡蛋白1（PD-1）/抗程序性死亡配体1（PD-L1）的免疫检查点抑制剂（ICI）治疗的主要抗肿瘤机制。研究目的：本研究旨在筛选与晚期肝细胞癌（HCC）免疫检查点抑制剂治疗疗效关联最紧密的T细胞耗竭相关标志物。研究方法：通过转录组学分析与多重免疫荧光染色，对存档肿瘤样本的免疫细胞组成进行了分析。研究结果：接受抗PD-1/抗PD-L1免疫检查点抑制剂治疗后获得客观缓解的肝细胞癌患者（n=42），其T细胞耗竭相关基因的表达水平更高。本研究构建了9基因特征（LAG3、CD244、CCL5、CXCL9、CXCL13、MSR1、CSF3R、CYBB及KLRK1），该特征的表达水平在免疫检查点抑制剂治疗应答患者中更高，与肿瘤微环境（tumor microenvironment）中CD8+LAG3+细胞的密度呈正相关，且可独立预测更好的无进展生存期与总生存期。该9基因特征对接受单药或联合免疫检查点抑制剂治疗的患者均具有相近的预测价值，且在接受手术治疗的肝细胞癌患者中与预后无显著关联，提示其在预测肝细胞癌免疫检查点抑制剂治疗疗效方面或优于其他T细胞特征。针对同时接受原发性肝癌与肺转移瘤切除术的肝细胞癌患者（n=31），肺转移性肝细胞癌的CD8 T细胞耗竭特征评分更高，这与既往研究观察到的肺转移性肝细胞癌患者对免疫检查点抑制剂治疗应答概率更高的结论一致。研究结论：肿瘤微环境中的CD8 T细胞耗竭可预测肝细胞癌免疫检查点抑制剂治疗的更佳疗效。