Introduction: Programmed death 1/programmed death ligand 1 (PD‐L1) axis inhibitors have been proven effective, especially in patients with tumors expressing PD‐L1. Their clinical efficacy in patients with EGFR‐activating mutations is still unclear, whereas KRAS mutations seem to be associated with good response. Methods: We used multiplexed quantitative immunofluorescence to investigate PD‐L1 expression and to characterize tumor infiltrating lymphocyte (TIL) populations and their activation status in more than 150 NSCLC patients with known mutation status. Results: PD‐L1 expression was significantly lower in EGFR‐mutant compared to KRAS‐mutant, and EGFR/KRAS wild‐type (WT) tumors. KRAS mutant tumors were more inflamed with higher CD4+, CD8+ and CD20+ TILs. Subgroup analysis by TIL activation status revealed that EGFR mutants had a high frequency of inactive TILs even though lymphocytes were present in the tumor microenvironment. In contrast, in KRAS mutants, when TILs were present they were almost always active. Additionally, we found differences between EGFR mutation sites in CD8+ expression and the TIL activation profile. Finally, activated EGFR correlated with increased PD‐L1 expression in EGFR mutants but not in EGFR WT, whereas TIL activation was associated with higher PD‐L1 only in EGFR/KRAS WT. Conclusions: Our findings show the unique immune profile of EGFR‐mutant tumors. The high frequency of inactive TILs could explain the low immunotherapy response rates in these patients, whereas PD‐L1 as a predictive biomarker may reflect the constitutive oncogenic signaling rather than immune signaling, which would be associated with high PD‐L1 levels and TILs activation.

中文翻译：

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非小细胞肺癌突变的免疫标志物分析和 PD-L1 表达

简介：程序性死亡 1/程序性死亡配体 1 (PD-L1) 轴抑制剂已被证明有效，尤其是在表达 PD-L1 的肿瘤患者中。它们对 EGFR 激活突变患者的临床疗效尚不清楚，而 KRAS 突变似乎与良好的反应相关。方法：我们使用多重定量免疫荧光来研究 PD-L1 表达并表征 150 多名具有已知突变状态的 NSCLC 患者的肿瘤浸润淋巴细胞 (TIL) 群体及其激活状态。结果：与 KRAS 突变体和 EGFR/KRAS 野生型 (WT) 肿瘤相比，EGFR 突变体中的 PD-L1 表达显着降低。KRAS 突变肿瘤因 CD4+、CD8+ 和 CD20+ TIL 的增加而更加发炎。TIL 激活状态的亚组分析显示，即使淋巴细胞存在于肿瘤微环境中，EGFR 突变体也具有高频率的无活性 TIL。相比之下，在 KRAS 突变体中，当 TIL 存在时，它们几乎总是活跃的。此外，我们发现 CD8+ 表达中的 EGFR 突变位点与 TIL 激活谱之间存在差异。最后，活化的 EGFR 与 EGFR 突变体中 PD-L1 表达增加相关，但与 EGFR WT 无关，而 TIL 激活仅与 EGFR/KRAS WT 中更高的 PD-L1 相关。结论：我们的研究结果显示了 EGFR 突变肿瘤的独特免疫特征。无活性 TIL 的高频率可以解释这些患者的低免疫治疗反应率，