Development of a Precision Drug to target Y537S Mutant Estrogen Receptor in Metastatic Breast Cancer

摘要 乳腺癌是美国最常见的癌症，也是第二大致死原因。 女人。大多数乳腺癌(~75%)表达雌激素受体α(ERα)蛋白，因此 内分泌治疗抑制这一蛋白功能是ER阳性乳腺癌的主要治疗方法 病人。然而，在接受内分泌治疗的妇女中，有近一半的人出现了获得性抵抗力。 与患者存活率低相关的治疗。具体地说，在相当多的情况下，延长 内分泌治疗会导致耐药肿瘤细胞的发展，从而导致肿瘤 复发，表现为极难管理的转移性疾病。最近，深层DNA 测序在一大群患者中发现了ERα基因(Esr1)特定位置的体细胞突变 乳腺癌已经扩散。具体地说，Y537S和D538G突变使ERα对电流产生抗性 内分泌治疗，因此，开发一种新的靶向治疗来解决这些临床问题是很重要的。 使用下一代ERα拮抗剂抑制ERα突变蛋白的挑战。我们的长期目标是 开发更有效和更安全的小分子药物来阻断结构性活性突变ER用于治疗 内分泌抵抗的转移性乳腺癌，有可能显著改善目前的治疗方法 目标策略。这种R21应用的短期目标是识别和开发特定的类药物 使用DNA编码的化学物质探测和提名针对ER突变蛋白的临床前候选蛋白 图书馆(Del)筛选平台。这项提案的目标将通过以下方式进行评估 具体目标：1.我们将进行DNA编码的化学文库筛选，以鉴定小分子结合剂 突变型ERα蛋白的配体结合区。2.我们将通过使用以下方法验证先导化合物并确定其优先顺序 生化和机能研究。我们的中心假设是具有高亲和力的小分子抗雌激素 ERα突变的特异性可以抑制ERα突变在乳腺癌中的作用。这项研究将为 为未来应用程序进行更详细的后续研究奠定基础。在成功执行本建议的 研究计划，我们预计已经确定了突变ER的先导化合物，并可用于未来的预 临床和临床研究。

ABSTRACT Breast cancer is the most frequently diagnosed cancer and the second leading cause of death in American women. The majority of breast cancer (~75%) expresses estrogen receptor α (ERα) protein and therefore inhibition of this protein function by endocrine therapy is the mainstay of treatment in ER-positive breast cancer patients. Nevertheless, acquired resistance has developed in nearly half of women treated with endocrine therapy that is associated with poor patient survival. Specifically, in a substantial number of cases, prolonged treatment with endocrine therapy creates the development of resistant tumor cells and, consequently, tumor relapse, which manifests as metastatic disease that is extremely difficult to manage. Recently, deep DNA sequencing has identified somatic mutations at specific sites in the ERα gene (ESR1) in a large subset of patients with breast cancers that have spread. Specifically, Y537S and D538G mutations make ERα resistant to current endocrine therapy and therefore, it is important to develop a novel targeted therapy to address these clinical challenges by inhibiting ERα mutant proteins using next-generation ERα antagonist. Our long-term goal is to develop more effective and safer small molecule drugs that block constitutively active mutant ER for treating endocrine resistant metastatic breast cancer and have the potential to significantly improve current therapeutic targeting strategies. The short-term goal of this R21 application is to identify and develop specific drug-like probes and nominate preclinical candidates to target ER mutant protein by using a DNA-encoded chemical library (DEL) screening platform. The objective of this proposal will be evaluated by addressing the following specific aims: 1. We will perform DNA-encoded chemical libraries screen to identity small-molecule binders to the ligand-binding domain of mutant ERα protein. 2. We will validate and prioritize lead compounds by using biochemical and functional studies. Our central hypothesis is that small molecule antiestrogens with high affinity and specificity for ERα mutants can inhibit ERα mutant function in breast cancer. This research will lay the groundwork for more detailed follow up studies for future applications. After successful execution of this proposed research plan, we expect to have identified lead compounds for mutant ER and that can be used for future pre- clinical and clinical studies.