Project 3: Adaptive immunity to MCPyV in Merkel cell carcinoma

摘要：项目3 默克尔细胞多瘤病毒(MCPyV)阳性的默克尔细胞癌(MCC)表现出显著和及时的 有机会解决肿瘤免疫学中的基本问题。在人类癌症中几乎是独一无二的，在 病毒阳性MCC(VP-MCC)，a)细胞转化需要一种非自身的病毒抗原，b)这些 癌蛋白较小且几乎没有多态，c)肿瘤突变负担很低，d)检测 病毒癌蛋白特异性的CD4和CD8T和B细胞经常是可能的，e)活检是 通常获得的。我们对MCPyV T抗原(T-Ag)的T细胞反应的研究为 抗PD-1治疗的试验。最近FDA批准的这些疗法改善了许多人的预后 患有晚期疾病。项目3侧重于患有当地或地区性疾病的人，他们共同患有 在目前的标准治疗后18个月复发的可能性为37%。 项目3由一位经验丰富的病毒免疫学家领导，也是P01团队的成员。我们的医疗中心 是一个建立良好的MCC转诊中心，因此来自已知结果的患者的存档标本 每年有70-80名新患者入院。近距离地剖析 关于MCPyV特异性获得性免疫和结局，我们提出了三个目标。目标1将决定 T-Ag特异性CD8 T细胞表型包括功能障碍和亲和力与临床的关系 早期MCPyV(+)MCC患者的预后。Aim 2将对T-Ag特异性进行类似的研究 CD4T细胞，包括在细胞和分子水平上对肿瘤CD4渗透的定量测量，以及 CD4T辅助细胞表型测定。T细胞研究将集中在TIL和血液上，两者都是 深刻的肿瘤抗原特异性T细胞定位和功能障碍。结果将与 抑制性肿瘤微环境的免疫组织化学研究。目标3针对抗体 对T-Ag的反应，它随着MCPyV(+)MCC患者的肿瘤负担而消长。升高的血清 抗T-Ag IgG预示肿瘤复发，系列检测包括在2018年NCCN MCC护理指南中。T- 将使用新的四聚体试剂在血液中检测到银特异的B细胞，并通过免疫球蛋白G测序和 详细的免疫表型鉴定。我们的研究小组在T-T细胞的免疫球蛋白基因中检测到了体细胞高度突变。 Ag特异的B细胞，表明这些细胞已经穿过生发中心，但未能分化为 长寿的抗体分泌细胞，一种非常不寻常的模式。项目3的基本前提是洞察力 我们将发表关于VP-MCC的获得性免疫将普遍适用于更难的恶性肿瘤 因为他们的肿瘤抗原在患者中很少保守。

Summary: Project 3 Merkel cell polyomavirus (MCPyV)-positive Merkel cell carcinoma (MCC) presents a significant and timely opportunity to address basic questions in tumor immunology. Almost uniquely amongst human cancers, in virus-positive MCC (VP-MCC), a) a non-self, viral antigen is required for cell transformation, b) these oncoproteins are small and have few polymorphisms, c) the tumor mutation burden is very low, d) detection of viral oncoprotein-specific CD4 and CD8 T- and B-cells is very frequently possible, and e) biopsies are commonly obtained. Our studies of T-cell responses to the MCPyV T-antigen (T-Ag) provided the rationale for trials of anti-PD-1 therapy. These recently FDA-approved therapies have improved outcomes for many persons with advanced disease. Project 3 focuses on persons with local or regional disease, who collectively have a 37% chance of recurrence at 18 months after current standard therapy. Project 3 is led by an experienced viral immunologist and member with the P01 team. Our medical center is a well-established referral center for MCC, such that archived specimens from patients with known outcomes are available and 70-80 new patients are enrolled annually. To closely dissect the relationship between MCPyV-specific acquired immunity and outcomes, we propose three Aims. Aim 1 will determine the relationship between T-Ag-specific CD8 T-cell phenotype including dysfunction and avidity, with clinical outcomes, in persons with early-stage MCPyV (+) MCC. Aim 2 will conduct similar studies of the T-Ag-specific CD4 T-cells, including quantitative measures of tumor CD4 infiltration at the cell and molecular levels, and measurement of CD4 T helper phenotype. T-cell studies will focus on both TIL and blood, the site of both profound tumor-antigen specific T-cell localization and dysfunction. Results will be correlated with immunohistochemical studies of the suppressive tumor microenvironment. Aim 3 addresses the antibody response to T-Ag, which waxes and wanes with tumor burden in persons with MCPyV (+) MCC. Rising serum anti-T-Ag IgG presages tumor relapse and serial testing is included in 2018 NCCN guidelines for MCC care. T- Ag-specific B cells will be detected in blood using novel tetramer reagents and studied by IgG sequencing and detailed immunophenotyping. Our group has detected somatic hypermutation in the IgG genes of validated T- Ag-specific B-cells, indicating that these cells have traversed the germinal center, yet fail to differentiate into long-lived antibody secreting cells, a very unusual pattern. The underlying Premise of Project 3 is that insights we will deliver regarding adaptive immunity in VP-MCC will be generally applicable to malignancies that are harder to study because their tumor antigens are seldom conserved among patients.