PO.TB10.19 · 肿瘤生物学
程序性细胞死亡配体1（PD-L1）在人乳腺高级别导管原位癌（DCIS）各分子亚型中的表达
Programmed cell death ligand 1 (PD-L1) expression across molecular subtypes of human high-grade ductal carcinoma in situ (DCIS) of the breast
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
背景：目前尚不清楚PD-L1在高级别乳腺DCIS肿瘤微环境（TME）中肿瘤浸润淋巴细胞（TILs）上的表达情况。
方法：可获取1996至2018年间诊断为DCIS的494例女性患者的福尔马林固定石蜡包埋标本，用于常规诊断性免疫组化（IHC）染色。ER和PR的IHC阳性定义为≥1%的阳性肿瘤细胞，HER2 IHC依据美国临床肿瘤学会和美国病理学家学会更新的指南进行评分，与常规诊断流程相同。当IHC评分为2+时进行HER2银染原位杂交。我们通过在两个独立的热点区计数200个导管内上皮细胞来计算Ki67比值。DCIS病例依据2013年圣加仑（St. Gallen）指南分类为Luminal A（LumA）、LumB HER2−、LumB HER2+、HER2富集型或三阴性（TPN）亚型，该指南用于浸润性乳腺癌的分子分型。每个亚型再分为“纯型”（Pure）：无浸润成分，以及“伴浸润”（W/invasive）：有浸润成分。我们通过计数（最多）1000个免疫细胞并除以PD-L1阳性细胞来计算PD-L1 IHC比值。PD-L1表达以1%为阈值进行二分。我们评估了PD-L1状态、亚型及其他变量（包括年龄、Ki67、DCIS范围和浸润性）之间的关联。
结果：我们在149/484（31%）例中鉴定出显著比例的TILs。这些病例100%为高级别DCIS。我们成功地对118/149例进行了PD-L1 IHC染色，其中73/118（63%）表达PD-L1≥1%。在92/149（62%）例伴有TILs的病例中，观察到强的膜阳性HER2过表达（25%为LumB HER2+，37%为HER2富集型亚型，p<0.0001）。相当数量（31/60；52%）的“伴浸润”病例含有TILs，而“纯型”为（118/362；32%）（p<0.0055）。PD-L1≥1%在HER2富集型（48.6%）和LumB HER2+（25%）亚型中最为常见，在LumA（12.5%）、LumB HER2−（9.7%）和TPN（4.2%）亚型中占比较低。然而，各亚型间PD-L1≥1%状态的比较得出无统计学意义的卡方结果（p=0.2734）。PD-L1表达与“伴浸润”病例无显著关联（p=0.0765）。在表达PD-L1≥1%的病例中，各亚型间在Ki67（p=0.0325）和DCIS范围（p=0.0323）上观察到显著差异，但在年龄（p=0.4329）或浸润状态（p=0.6722）上无差异。
结论：PD-L1≥1%在HER2驱动的亚型中更常见，但其分布并不依赖于亚型。PD-L1表达也缺乏与浸润性的显著关联。这些发现证明了高级别DCIS中存在强的PD-L1表达，尽管PD-L1作为DCIS患者亚型分层或浸润潜能预测的独立生物标志物的效用可能有限。
查看英文原文 English abstract
Background: The expression of PD-L1 in tumor-infiltrating lymphocytes (TILs) in tumor microenvironment (TME) of high-grade breast DCIS is currently unknown.
Methods: Formalin-fixed paraffin-embedded specimens from 494 female patients diagnosed with DCIS between 1996-2018 were available to routine diagnostic immunohistochemical (IHC) staining. ER and PR IHC positivity was defined as ≥1% positive tumor cells, and HER2 IHC was scored based on the updated guidelines of the American Society of Clinical Oncology and the College of American Pathologists, as in routine diagnostic procedures. HER2 silver in situ hybridization was performed when the IHC score was 2+. We calculated the Ki67 ratio by counting 200 intraductal epithelial cells in two separate hotspot foci. DCIS cases were classified as Luminal A (LumA), LumB HER2ˉ, LumB HER2 + , HER2-enriched, or triple-negative (TPN) subtypes according to the 2013 St. Gallen guidelines, which is used for molecular subtyping of invasive breast carcinoma. Each subtype was sorted into “Pure”: without an invasive component and “W/invasive”: with an invasive component. We calculated the PD-L1 IHC ratio by counting (up to) 1000 immune cells divided by positive PD-L1 cells. PD-L1 expression was dichotomized at a threshold of 1%. We assessed the associations between PD-L1 status, subtype, and other variables, including age, Ki67, DCIS extension, and invasiveness.
Results: We identified a significant proportion of TILs in 149/484 (31%) cases. 100% of these cases were high-grade DCIS. We successfully stained 118/149 cases with PD-L1 IHC, and 73/118 (63%) expressed PD-L1 ≥1%. In 92/149 (62%) cases with TILs, strong membrane-positive HER2 overexpression was observed (25% LumB HER2 + and 37% HER2-enriched subtype, p < 0.0001). A significant number (31/60; 52%) of the “W/invasive” cases contained TILs, compared to “Pure” (118/362; 32%) ( p < 0.0055). PD-L1 ≥1% was most prevalent in HER2-enriched (48.6%) and LumB HER2 + (25%) subtypes, with lower representation in LumA (12.5%), LumB HER2ˉ (9.7%), and TPN (4.2%) subtypes. However, comparison of the PD-L1 ≥1% status across subtypes yielded a non-significant chi-square result ( p = 0.2734). PD-L1 expression was not significantly associated with “W/invasive” cases ( p = 0.0765). Significant differences were observed across subtypes among cases expressing PD-L1 ≥1% for Ki67 ( p = 0.0325) and DCIS extension ( p = 0.0323), but not for age ( p = 0.4329) or invasive status ( p = 0.6722).
Conclusions: PD-L1 ≥1% was more common in HER2-driven subtypes, but its distribution was not subtype-dependent. PD-L1 expression also lacked a significant association with invasiveness. These findings demonstrated strong PD-L1 expression in high-grade DCIS, although the utility of PD-L1 as a standalone biomarker for subtype stratification or prediction of invasive potential in DCIS patients could be limited.
利益披露 Disclosure
H. Schandiz, None..
L. Farkas, None..
B. Gravdehaug, None..
E. S. Agustsdottir, None..
T. Sauer, None..
J. Geisler, None.