Project 1: Improved Targeting of EGFR Family Members in Squamous Cell Carcinomas of the Head and Neck

摘要 表皮生长因子受体(Egfr)仍然是头颈部唯一有效的分子靶点。 鳞状细胞癌(HNSCC)，介导细胞生存信号和放射治疗的抵抗。 尽管西妥昔单抗等EGFR靶向治疗取得了成功，但对EGFR靶向的治疗抵抗 最终会发展成。改进EGFR靶向治疗的一个重大挑战是识别和临床 验证治疗耐药的可操作机制。在这项提案中，我们设计了一项战略， 在基础科学研究、临床前测试和临床标本测试之间反复进行，以阐明 HNSCC对西妥昔单抗耐药机制的研究。使用体外方法分析西妥昔单抗的耐药性， 我们发现靶向自分泌配体NRG-1的上调是耐药的靶向机制。我们 利用小鼠异种移植研究，在细胞系和体内模拟了这种耐药性，并显示了 它可以通过使用ErbB3靶向抗体治疗性(CDX-3379)来逆转-它 可以恢复对西妥昔单抗和放射治疗的反应。我们还观察到NRG-1诱导的抗性 肿瘤细胞中的小分子EGFR激酶抑制剂，并研究了其机制来源 结构层面的阻力。我们建议利用这一新知识来推动小分子 针对HNSCC中EGFR家族成员的方法。在进行这些研究的同时，我们还将研究临床 来自正在进行的Aafatinib加西妥昔单抗的HNSCC第二阶段试验的样本，以及两个ECOG试验 西妥昔单抗，研究临床耐药机制。我们还将开发患者来源的异种移植物 来自正在进行的临床试验的(PDX)模型，以测试耐药机制的假设并评估 为克服这一问题而设计的新战略的有效性。 该提案的关键前提是了解西妥昔单抗的耐药机制将开放 新的治疗机会--允许我们开发在西妥昔单抗治疗时仍能抑制EGFR的方法 失败，并开发方法来靶向以西妥昔单抗不敏感的方式激活EGFR的其他分子 (如ErbB3)。我们的三个具体目标是： 1.阐明HNSCC细胞对西妥昔单抗耐药的机制并建立耐药模型，检测CDX-3379作为新的抗肿瘤药物 以erbB3为靶点的方法，加强HNSCC的全身和/或放射治疗。 2.为成功的小分子靶向ErbB受体开发新的结构/机制导向策略 HNSCC中的分子酪氨酸激酶抑制物(TKIs)。 3.使用临床试验样本确定ErbB靶向治疗疗效的生物标志物，并 建立平行的患者来源肿瘤模型以评估ErbB靶向耐药机制 HNSCC的治疗。

SUMMARY The epidermal growth factor receptor (EGFR) remains the only validated molecular target in head and neck squamous cell carcinoma (HNSCC), mediating cell survival signaling and resistance to radiation therapy. despite the success of EGFR targeted therapies such as cetuximab, therapeutic resistance to EGFR targeting ultimately develops. A significant challenge for improving EGFR targeted therapies is to identify and clinically validate actionable mechanisms of therapeutic resistance. In this proposal, we have designed a strategy that iterates between basic science investigations, preclinical testing, and clinical specimen testing to elucidate the mechanism of cetuximab resistance in HNSCC. Using an in vitro approach for analyzing cetuximab resistance, we identified upregulation of a targetable autocrine ligand, NRG-1, as a target mechanism of resistance. We have modeled this resistance both in cell lines and in vivo, using mouse xenograft studies, and have shown that it can be reversed therapeutically by using an ErbB3-targeted antibody therapeutic (CDX-3379) – which can restore responses to cetuximab and radiation therapy. We have also observed NRG-1-induced resistance to small molecule EGFR kinase inhibitors in cancer cells, and have studied the mechanistic origin of this resistance at a structural level. We propose to exploit this new knowledge to advance small molecular approaches for targeting EGFR family members in HNSCC. In parallel with these studies, we will study clinical specimens from an ongoing phase II HNSCC trial of afatinib plus cetuximab, plus two ECOG trials of cetuximab, to investigate resistance mechanisms in the clinic. We will also develop patient-derived xenografts (PDX) models from the ongoing clinical trial to test hypotheses for resistance mechanisms and to assess effectiveness of new strategies devised to overcome it. The key premise of the proposal is that understanding mechanisms of resistance to cetuximab will open up new therapeutic opportunities – allowing us to develop approaches that can still inhibit EGFR when cetuximab fails, and to develop approaches to target other molecules that activate EGFR in a cetuximab-insensitive way (such as ErbB3). Our three Specific Aims are: 1. To elucidate and model mechanisms of cetuximab resistance in HNSCC, and to test CDX-3379 as a new ErbB3 targeted approach for enhancing systemic and/or radiation therapy in HNSCC. 2. To develop new structure/mechanism-guided strategies for successful ErbB-receptor targeting with small molecule tyrosine kinase inhibitors (TKIs) in HNSCC. 3. To identify biomarkers of therapeutic response to ErbB-targeted therapies using clinical trial samples, and to establish parallel patient-derived tumor models to evaluate mechanisms of resistance to ErbB-targeted therapies in HNSCC.