Immune activation by cetuximab in head and neck cancer patients

描述（由申请人提供）：有令人信服的临床证据表明，表皮生长因子受体（EGFR）特异性单克隆抗体（mAb）西妥昔单抗仅对晚期头颈部鳞状细胞癌（HNC）的一部分有效。因此，有必要了解为什么临床反应因人而异。与EGFR酪氨酸激酶抑制剂相比，单克隆抗体的使用提高了免疫系统可能在这种临床活动中发挥作用的潜力。此外，由于西妥昔单抗在体外治疗HNC细胞不会诱导显著的细胞凋亡，体内的抗肿瘤作用可能部分归因于其他因素，例如通过自然杀伤（NK）细胞和单核细胞介导的抗体依赖性细胞毒性（ADCC）激活免疫细胞，通过mAb的恒定片段（Fc）结构域结合多态Fc？受体(Fc ? R)。然而，对于T细胞是否有助于单克隆抗体治疗或多态Fc？Rs影响T细胞反应的诱导。HNC细胞频繁下调HLA I类抗原加工机制（APM）和NK抑制分子的表达，可能提供了HNC细胞抵抗NK细胞和肿瘤抗原特异性T细胞裂解的机制。因此，我们假设免疫系统的细胞臂在介导西妥昔单抗的抗肿瘤作用中起重要作用。我们有证据证明Fc？R在Fc？RIIa131R/H和FcRIII158V/F影响健康供体和HNC患者PBMC中ADCC活性，这些密码子也与单药西妥昔单抗治疗结直肠癌患者的预后相关。此外，我们还发现TNF-a、IFN-？MIP-1a和MIP-1¿在ADCC响应PBMC的体外上清液中一致表达。这些细胞因子和趋化因子从活化的NK细胞中释放出来，对T细胞和树突状细胞（DC）具有趋化作用，表明西妥昔单抗诱导NK细胞裂解和ta特异性T细胞诱导之间存在潜在联系。了解这些单抗的免疫介导机制是很重要的：(1)选择最合适的患者进行西妥昔单抗治疗，具有最大的免疫激活能力；(2)增强抗肿瘤ADCC和T细胞活性，以增加西妥昔单抗治疗患者的反应；(2)识别生物学和临床反应的预测性免疫生物标志物，如Fc？R多态性、细胞免疫和免疫逃逸机制。不同EGFR表达和淋巴细胞水平的HNC小鼠模型，以Fc？来自不同疾病阶段的HNC患者的R基因型，在存在或不存在放化疗或肿瘤表达NK抑制分子的情况下，将用于检验PBMC表达某些Fc？R基因型或来自晚期HNC患者影响抗肿瘤活性。此外，我们将确定西妥昔单抗是否通过DC成熟和交叉呈递增强抗原特异性T细胞诱导，这是受Fc？R多态性，西妥昔单抗和NK细胞。最后，我们提议在匹兹堡大学进行的一项II期单药西妥昔单抗临床试验（08-013）中，确定西妥昔单抗对HNC患者NK和T细胞活化、肿瘤浸润以及HNC标本中APM表达缺陷的影响。

DESCRIPTION (provided by applicant): There is convincing clinical evidence that the epidermal growth factor receptor (EGFR)-specific monoclonal antibody (mAb), cetuximab, is effective therapy only for a subset of advanced head and neck squamous cell carcinoma (HNC). Thus, there is a need to understand why clinical responses vary between individuals. In contrast to EGFR tyrosine kinase inhibitors, the use of a mAb raises the potential that the immune system might play a role in this clinical activity. Also, since treatment of HNC cells with cetuximab does not induce significant apoptosis in vitro, anti-tumor effects in vivo may be due in part to additional factors, such as immune cell activation through antibody dependent cellular cytotoxicity (ADCC) mediated by natural killer (NK) cells and monocytes, through the constant fragment (Fc) domain of the mAb binding to polymorphic Fc? receptors (Fc?R). However, little is known about whether T cells contribute to mAb therapies or whether polymorphic Fc?Rs influence the induction of T cell responses. The frequent downregulation of HLA class I antigen processing machinery (APM) and expression of NK inhibitory molecules by HNC cells, may provide a mechanism of resistance to NK cell- and tumor antigen specific T cell lysis of HNC cells. Thus, we hypothesize that the cellular arm of the immune system plays an important role in mediating the anti-tumor effects of cetuximab. We have evidence that Fc?R polymorphisms at Fc?RIIa131R/H and FcRIII158V/F influence ADCC activity in PBMC of healthy donors and HNC patients, and these codons also correlate with outcome of colorectal cancer patients treated with single agent cetuximab. In addition, we have identified that TNF-a, IFN-?, MIP-1a, and MIP-1¿, are consistently expressed in vitro in the supernatant of ADCC responding PBMC. Released from activated NK cells, these cytokines and chemokines are chemotactic for T cells and dendritic cells (DC) cells, suggesting a potential link between cetuximab-induced NK lysis and induction of TA-specific T cell induction. Understanding immune mediated mechanisms of these mAb is important: (i) to select the most appropriate patients for cetuximab therapy with greatest ability to mount immune activation, (ii) to enhance anti-tumor ADCC and T cell activity in order to increase responses in cetuximab-treated patients and (ii) to identify predictive immune biomarkers of biological and clinical responsiveness, such as Fc?R polymorphisms, cellular immunity and immune escape mechanisms. A HNC murine model with different levels of EGFR expression and lymphocytes, characterized by Fc?R genotype from HNC patients of different disease stage and in the presence or absence of chemoradiotherapy or NK inhibitory molecules expressed by the tumor, will be used to test the hypothesis that PBMC expressing certain Fc?R genotypes or from advanced HNC patients influences antitumor activity. In addition we will determine whether cetuximab enhances antigen specific T cell induction by DC maturation and cross-presentation, which is influenced by Fc?R polymorphisms, cetuximab and NK cells. Lastly we propose to determine the effect of cetuximab responsiveness in HNC patients on NK and T cell activation, tumor infiltration, and defects in APM expression in HNC specimens from a phase II, single agent cetuximab clinical trial (08-013) at the University of Pittsburgh.