CD8^(+)T细胞联合PD-L1 mRNA对pMMR型结直肠癌根治术预后及免疫疗效的影响

Effect of CD8^(+)T cell combined with PD-L1 mRNA on the survival of pMMR colorectal cancer after radical resection and the efficacy of immunotherapy

目的 探讨CD8^(+)T细胞计数和程序性死亡配体-1(PD-L1)mRNA表达水平联合指数对预测错配修复完整(pMMR)型结直肠癌患者根治术后远期生存及免疫治疗近期疗效的作用。方法 对2013-02-12-2014-03-31在哈尔滨医科大学附属肿瘤医院行结直肠癌根治术的257例患者,以及2019-01-07-2020-12-22于本院接受抗程序性死亡受体-1(PD-1)治疗(单药或联合)的38例晚期pMMR型结直肠癌患者的病理组织进行分析,分别应用免疫组织化学染色法和原位杂交法检测病理组织中CD8^(+)T细胞计数和PD-L1 mRNA的表达水平,同时分析联合指数是否可以预测根治术后结直肠癌患者的远期生存及pMMR型结直肠癌患者接受抗PD-1治疗(单药或联合)的近期疗效。Kaplan-Meier方法绘制生存曲线,单因素Cox比例风险模型确定CD8^(+)T细胞丰度与生存是否相关。Fisher确切概率法检查联合指数阴性和阳性组与客观缓解率和疾病控制率的关系。结果 PD-L1 mRNA表达水平与结直肠癌患者的错配修复状态有关联,P=0.045。PD-L1 mRNA表达水平与pMMR型根治术后结直肠癌患者的总生存期(OS)呈正相关,HR=0.304,95%CI为0.145~0.639,P=0.001;而与错配修复缺失(dMMR)型结直肠癌患者预后无关,HR=1.881,95%CI为0.505~7.007,P=0.338。PD-L1 mRNA在肿瘤组织的表达强度与CD8^(+)T细胞的浸润程度存在关联性,P=0.005。受试者工作特征(ROC)曲线及单因素分析显示,CD8^(+)T细胞密度≥21.8 HPF患者具有更好的OS,HR=0.400,95%CI为0.182~0.879,P=0.018。CD8^(+)T细胞与PD-L1 mRNA联合指数的临界条件设定为CD8^(+)T细胞≥21.8 HPF和PD-L1 mRNA (+++),符合患者为适用组,其OS优于非适用组,HR=0.318,95%CI为0.100~1.014,P=0.040。回顾性分析显示,适用组pMMR型结直肠癌患者接受抗PD-1治疗(单药4例,联合34例),具有更高的客观缓解率(4/9 vs 3/29,P=0.041)和疾病控制率(8/9 vs 8/29,P=0.002)。结论 符合联合指数CD8^(+)T细胞≥21.8 HPF和PD-L1 mRNA(+++)的根治术后pMMR型结直肠癌患者更具生存优势,且更有潜力从抗PD-1联合治疗中获益。

Objective To explore the role of the combination index of CD8^(+)T cell count and programmed cell death-ligand 1(PD-L1) mRNA expression level in predicting the efficacy of mismatch repair-proficient(pMMR) colorectal cancer after radical surgery and the short-term efficacy of immunotherapy.Methods We analyzed the pathological tissues from Harbin Medical University Cancer Hospital, including 257 colorectal cancer patients after radical resection during February 12,2013 to March 31,2014 and 38 patients with advanced pMMR colorectal cancer after anti-programmed cell death protein-1(PD-1) treatment during January 7,2019 to December 22,2020.The count of CD8^(+)T cell and level of PD-L1 mRNA in pathological tissues were detected by immunohistochemical staining and in situ hybridization, respectively.Meanwhile, survival analysis and efficacy evaluation were performed to determine whether the combination index could predict the long-term survival of patients with pMMR colorectal cancer after radical resection and the short-term efficacy of anti-PD-1 therapy(monotherapy or combination therapy) in patients with pMMR colorectal cancer.Kaplan-meier method was used to plot survival curve,and univariate Cox proportional risk model was used to determine whether CD8^(+)T cell abundance was correlated with survival.Fisher’s exact test was used to examine the relationship between negative and positive groups of combination index and objective response rate or disease control rate.Results PD-L1 mRNA expression level was significantly associated with mismatch repair status in patients with colorectal cancer,P=0.045.PD-L1 mRNA expression was positively correlated with overall survival(OS)in patients with pMMR colorectal cancer after radical resection,HR=0.304,95% CI was 0.145-0.639,P=0.001;but it was not associated with prognosis in patients with dMMR colorectal cancer,HR=1.881,95% CI was 0.505-7.007,P=0.338.There was relevance between the expression intensity of PDL1 mRNA and the invasion degree of CD8^(+)T cell in tumor,P=0.005.ROC curve and univariate analysis showed that patients with CD8^(+)T cell density greater than or equal to 21.8 HPFhad better OS,HR=0.400,95% CI was 0.182-0.879,P=0.018.The critical condition for the combination index of CD8^(+)T cell and PD-L1 mRNA was set as CD8^(+)T cell≥21.8 HPFand PD-L1 mRNA(+ + +).Patients meeting the combination index were classified as applicable group,whose OS were better than those in non-applicable group,HR=0.318,95%CI was 0.100-1.014,P=0.040.Retrospective analysis showed that patients with pMMR colorectal cancer meeting the above criteria had higher objective response rate(5/9 vs 2/29,P=0.041)and disease control rate(8/9 vs 8/29,P=0.002)after anti-PD-1 therapy(4 cases of monotherapy and 34 cases of combination therapy).Conclusions Patients with pMMR colorectal cancer whose combination index of CD8^(+)T cell and PD-L1 mRNA match CD8^(+)T cell≥21.8HPFand PD-L1 mRNA(+++)have a better survival advantage after radical resection and are more potential to benefit from anti-PD-1 combination therapy.