Enhancement of ADC selectivity by inverse targeting: Mechanistic studies and optimization

癌症是美国发病率和死亡率的主要原因，有180万例，60万癌症 预计2020年死亡。在过去的二十年里，癌症治疗取得了实质性的进展， 主要是通过开发高度靶向的疗法，包括开发抗体-药物缀合物 （ADC）。ADC采用对肿瘤相关抗原具有特异性的单克隆抗体，以增加肿瘤相关抗原的表达。 抗癌毒素递送的效率和选择性（即，payloads）到癌细胞。虽然这 方法已被证明是成功的，有9种抗癌ADC在美国被批准使用（维布妥昔单抗， 曲妥珠单抗emtansine、吉妥珠单抗ozogamicin、inotuzumab ozogamicin、polatuzumab vedotin、enfortumab vedotin、belantamab mafodotin、曲妥珠单抗deruxtecan和sacituzumab govitecan），ADC疗法通常是 与临床上大量的脱靶毒性、狭窄的治疗窗和高失败率相关 试验.该项目引入了一种新的药代动力学策略，以增加抗体的肿瘤选择性， 抗癌药物的定向递送。在我们的方法中，有效载荷结合抗体片段，称为有效载荷- 结合选择性增强剂（PBSE）与ADC共同施用以减少健康人的暴露。 组织的有效载荷剂，从而减少脱靶毒性的发展，增加耐受剂量 增加ADC的功效。该策略基于以下认识： 主要归因于释放的（“游离”）有效载荷分子，并且还基于PBSE可能是 用于防止游离有效载荷分子进入非靶细胞（通过防止扩散穿过 质膜），而不改变ADC进入靶细胞（其通过受体介导的细胞内 内吞作用）。本项目的工作将集中于开发和评估一系列新颖的PBSE， 已显示降低游离SN 38和Dxd的细胞毒性。这些药物是喜树碱衍生物 作为sacituzumab govitecan和trastuzumab deruxtecan的有效载荷， ADC分子在临床研究中显示出一定的功效，但具有相当大的毒性。机械论 目标#1和目标#2中提出的研究检查PBSE分子属性之间的关系（例如，亲和力， 分子形态[即，IgG、Fab、scFv、sdAb]、对未缀合的有效负载的选择性、分子电荷等）和 PBSE在增强ADC治疗的药代动力学和药效学选择性中的效用。这些发现 将通过使用机械数学建模来集成，以帮助选择最佳的 目的#3中用于评价疗效和毒性的药物和给药方案。在此期间开发的新型药物 工作可能适合于立即转化为sacituzumab govitecan和曲妥珠单抗的优化 deruxtecan治疗难治性和耐药性乳腺癌。

Cancer is a major cause of morbidity and mortality in the US, with 1.8 million cases and 600 thousand cancer deaths projected for 2020. Substantial progress in cancer treatment has been made in the past two decades, largely through the development of highly targeted therapies, including development of antibody-drug conjugates (ADCs). ADCs employ monoclonal antibodies with specificity for tumor-associated antigens to increase the efficiency and selectivity of the delivery of anti-cancer toxins (i.e., payloads) to cancer cells. Although this approach has proven to be successful, with 9 anti-cancer ADCs approved for use in the US (brentuximab vedotin, trastuzumab emtansine, gemtuzumab ozogamicin, inotuzumab ozogamicin, polatuzumab vedotin, enfortumab vedotin, belantamab mafodotin, trastuzumab deruxtecan, and sacituzumab govitecan), ADC therapies are often associated with substantial off-target toxicity, narrow therapeutic windows, and high failure rates in clinical testing. This project introduces a new pharmacokinetic strategy to increase the tumor-selectivity of antibody- directed delivery of anti-cancer drugs. In our approach, payload-binding antibody fragments, termed payload- binding selectivity enhancers (PBSE), are co-administered with ADCs to decrease the exposure of healthy tissues to payload agents, thereby reducing the development of off-target toxicity, increasing the tolerable dose of ADCs, and increasing ADC efficacy. The strategy is based on the recognition that off-site ADC toxicity is primarily attributed to the released (“free”) payload molecule, and also on the hypothesis that PBSE may be employed to prevent cellular entry of free payload molecules in non-targeted cells (by preventing diffusion across plasma membranes) without altering entry of ADCs into targeted cells (which proceeds via receptor mediated endocytosis). Work in this project will focus on the development and evaluation of a novel series of PBSE that have been shown to decrease the cytotoxicity of free SN38 and Dxd. These agents are camptothecin derivatives that are employed as payloads for sacituzumab govitecan and trastuzumab deruxtecan, two recently approved ADC molecules that have shown some efficacy, but substantial toxicity, in clinical investigations. Mechanistic studies proposed in Aim #1 and Aim #2 examine relationships between PBSE molecular attributes (e.g., affinity, molecular modality [i.e., IgG, Fab, scFv, sdAb], selectivity for unconjugated payload, molecular charge, etc.) and PBSE utility in enhancing the pharmacokinetic and pharmacodynamic selectivity of ADC therapy. These findings will be integrated through the use of mechanistic mathematical modeling to assist in the selection of an optimal agent and dosing regimen for evaluation of efficacy and toxicity in Aim #3. The novel agents developed in this work may be suitable for immediate translation toward optimization of sacituzumab govitecan and trastuzumab deruxtecan therapy of refractory and resistant breast cancer.