PD-L1（CD274）扩增发生在少数恶性肿瘤中，并可能预测免疫治疗的抗-PD-1/PD-L1反应性。我们假设，肿瘤相关PD-L1扩增的拷贝数（CN）和焦点性会影响蛋白质表达，并分析了在Foundation Medicine于2016年3月至2022年2月期间进行全面基因组分析的实体肿瘤样本。使用比较基因组杂交样品测序法检测到PD-L1 CN变化，并通过免疫组化（IHC）与PD-L1蛋白表达（DAKO 22C3抗体）进行相关性分析。总体上，分析了60,793个样本（最常见的组织学类型为肺腺癌（20％）、结肠腺癌（12％）、肺鳞癌（8％））。使用CD274 CN ≥ 样本倍体数+4（6个拷贝）的定义，发现1.21％的肿瘤（738/60793）具有PD-L1扩增。焦点性别类分布如下：<0.1 mB（n=18（2.4％）），≥0.1至<4 mB（n=230（31.1％）），≥4至<20 mB（n=310（42％）），≥20 mB（n=180（24.4％））。较低水平的PD-L1扩增（低于样本倍体数+4）相对更常见于非焦点扩增比高水平。此外，更焦点的扩增（<0.1 mB）与更高的PD-L1 IHC表达相关。根据焦点，PD-L1扩增（倍性≥+4）样本的中位瘤细胞比例分数（TPS）分别为87.5％（<0.1 mB），80％（≥0.1至<4 mB），40％（≥4至<20 mB），1％（≥20 mB）。在PD-L1倍性小于+4但高度焦点性（<0.1 mB）的样本中，TPS为PD-L1表达量的第75个百分位为80％。相反，非焦点（≥20 mB）PD-L1扩增（倍数≥+4）可能表现出高PD-L1表达（TPS≥50％），尽管很少见（我们队列中的0.09％）。总之，IHC测量的PD-L1表达受PD-L1扩增水平和焦点影响。 PD-L1等可靶向基因的扩增、焦点、蛋白质表达和治疗效果之间的进一步相关性有待探索。 ©作者（或其雇主（们））2023。 在CC BY-NC下允许重复使用。 不得进行商业重用。由BMJ出版。

PD-L1 (CD274) amplification occurs in a small subset of malignancies and may predict anti-PD-1/PD-L1 immunotherapy responsiveness. We hypothesized that both copy number (CN) and focality of cancer-related PD-L1 amplifications impact protein expression, and, thus, analyzed solid tumors that underwent comprehensive genomic profiling between March 2016 and February 2022 at Foundation Medicine. PD-L1 CN alterations were detected using a comparative genomic hybridization-like method. PD-L1 CN changes were correlated with PD-L1 protein expression (DAKO 22C3 antibody) by immunohistochemistry (IHC). Overall, 60,793 samples were analyzed (most frequent histologies: lung adenocarcinoma (20%), colon adenocarcinoma (12%), lung squamous carcinoma (8%)). Using a definition of CD274 CN ≥ specimen ploidy +4 (6 copies), 1.21% of tumors (738/60,793) were PD-L1 amplified. Focality category distribution was as follows: <0.1 mB (n=18 (2.4%)), ≥0.1 to <4 mB (n=230 (31.1%)), ≥4 to <20 mB (n=310 (42%)), ≥20mB (n=180 (24.4%)). Lower levels of PD-L1 amplification (below specimen ploidy +4) were more frequently non-focal amplifications compared to higher levels. In addition, more focal amplification (<0.1 mB) correlated with higher PD-L1 IHC expression. Median tumor proportion score (TPS) for samples with PD-L1 amplification (ploidy ≥+4) according to focality were 87.5% (<0.1 mB), 80% (≥0.1 to <4 mB), 40% (≥4 to <20 mB), 1% (≥20mB). In specimens with PD-L1 ploidy less than +4, but highly focal (<0.1 mB), the 75th percentile of PD-L1 expression by TPS was 80%. Conversely, non-focal (≥20 mB) PD-L1 amplification (ploidy ≥+4) can present high PD-L1 expression (TPS≥50%), albeit infrequently (0.09% of our cohort). In conclusion, PD-L1 expression measured by IHC is influenced by PD-L1 amplification level and focality. Further correlation between amplification, focality, protein expression and therapeutic outcome for PD-L1 and other targetable genes warrants exploration.© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.