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

总结 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），介导细胞存活信号传导和对放射疗法的抗性。 尽管EGFR靶向治疗如西妥昔单抗取得了成功， 最终发展。改善EGFR靶向治疗的一个重大挑战是在临床上识别和治疗EGFR靶向治疗。 验证治疗抗性的可行机制。在这份提案中，我们设计了一项战略， 在基础科学研究、临床前测试和临床样本测试之间进行迭代，以阐明 HNSCC中西妥昔单抗耐药的机制。使用体外方法分析西妥昔单抗耐药性， 我们鉴定了靶向自分泌配体NRG-1的上调作为耐药的靶机制。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， 它可以通过使用ErbB 3靶向抗体治疗剂（CDX-3379）在治疗上逆转， 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 小分子EGFR激酶抑制剂在癌细胞中的作用，并研究了这种作用的机制起源。 在结构层面的阻力。我们建议利用这一新知识， 在HNSCC中靶向EGFR家族成员的方法。在这些研究的同时，我们将研究临床 来自正在进行的阿法替尼+西妥昔单抗II期HNSCC试验的标本，以及两项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 (PDX)正在进行的临床试验的模型，以测试耐药机制的假设，并评估 为克服这一问题而制定的新战略的有效性。 该提案的关键前提是，了解西妥昔单抗耐药机制将打开 新的治疗机会-使我们能够开发出在西妥昔单抗治疗时仍然可以抑制EGFR的方法， 失败，并开发以西妥昔单抗不敏感方式激活EGFR的其他分子为靶点的方法 (such作为ErbB 3）。我们的三个具体目标是： 1.为了阐明HNSCC中西妥昔单抗耐药的机制并建立模型，并测试CDX-3379作为新的抗肿瘤药物。 ErbB 3靶向方法用于增强HNSCC中的全身和/或放射治疗。 2.为了开发新的结构/机制指导的策略，成功地用小分子药物靶向ErbB受体， 分子酪氨酸激酶抑制剂（TKI）。 3.使用临床试验样本鉴定ErbB靶向治疗的治疗应答生物标志物， 建立平行的患者源性肿瘤模型，以评估对ErbB靶向药物的耐药机制 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.