Table_2_Merkel Cell Polyoma Viral Load and Intratumoral CD8+ Lymphocyte Infiltration Predict Overall Survival in Patients With Merkel Cell Carcinoma.docx

Introduction: Merkel cell carcinoma (MCC) is linked to the presence of clonally integrated Merkel cell polyomavirus (MCPyV) in up to 80% of the cases. The aim of the study was to determine the prognostic value of baseline MCPyV viral load and lymphocytic infiltration.
Methods: MCPyV DNA prevalence, integration status and viral load were determined by specific quantitative real-time PCR in surgical specimens obtained from 49 patients with MCC treated with (n = 22, 45%) or without postoperative radiotherapy (RT). CD8+ tumor infiltrating lymphocytes (TILs) and programmed death ligand 1 (PD-L1) status were assessed using immunohistochemistry. MCPyV characteristics and immune marker expression were correlated with clinicopathological factors and overall survival (OS).
Results: Median age at diagnosis was 74 (range, 42–100); 51% of the patients were female. One-, three, and five-year OS rates were 83.8, 58.6, and 47.1%, respectively. A positive MCPyV status was associated with female gender (p = 0.042). Tumor localization (head/arms vs. trunk) positively correlated with PD-L1 status (p = 0.011) and combined CD8/PD-L1 expression (p = 0.038). Overall CD8+ infiltration was inversely associated with N-stage (p = 0.048). Stromal TILs correlated significantly with both PD-L1 expression (p = 0.010) and N-stage (p = 0.037). A high viral load (>median) was significantly associated with worse OS (p = 0.029) and high intratumoral CD8+ infiltration with improved OS for the entire cohort (p = 0.045).
Conclusion: These data provide important insight on the role of MCPy DNA viral load and TILs in the context of PD-L1 in patients with Merkel cell carcinoma. Future clinical studies should aim to explore the effect of PD-1/PD-L1 immune-checkpoint inhibitors in combination with existing radiotherapy approaches.

引言：默克尔细胞癌（Merkel cell carcinoma, MCC）的发生与高达80%的病例中存在克隆整合型默克尔细胞多瘤病毒（Merkel cell polyomavirus, MCPyV）密切相关。本研究旨在明确基线MCPyV病毒载量及淋巴细胞浸润的预后价值。

方法：本研究纳入49例经治的MCC患者，其中22例（45%）接受术后放疗（postoperative radiotherapy, RT），其余患者未接受该治疗；采用特异性实时定量聚合酶链反应对所有患者的手术标本进行检测，以明确MCPyV DNA的检出率、整合状态及病毒载量。采用免疫组织化学法检测CD8+肿瘤浸润淋巴细胞（tumor infiltrating lymphocytes, TILs）的浸润情况及程序性死亡受体配体1（programmed death ligand 1, PD-L1）的表达状态。将MCPyV相关特征与免疫标志物表达水平与临床病理参数及总生存期（overall survival, OS）进行相关性分析。

结果：患者诊断时的中位年龄为74岁（范围42~100岁），其中女性占比51%。1年、3年及5年总生存率分别为83.8%、58.6%及47.1%。MCPyV阳性状态与女性性别显著相关（p=0.042）。肿瘤部位（头颈部/上肢 vs 躯干）与PD-L1表达状态（p=0.011）及CD8与PD-L1联合表达（p=0.038）均呈正相关。总体CD8+浸润程度与N分期呈负相关（p=0.048）。间质TILs与PD-L1表达（p=0.010）及N分期（p=0.037）均显著相关。高病毒载量（>中位值）与较差的总生存期显著相关（p=0.029）；而瘤内CD8+高浸润则与全队列患者更好的总生存期相关（p=0.045）。

结论：本研究数据为阐明MCPyV DNA病毒载量及TILs在PD-L1相关背景下对默克尔细胞癌患者的作用提供了重要见解。未来的临床研究应探索PD-1/PD-L1免疫检查点抑制剂联合现有放疗方案的治疗效果。