Novel Protein Engineered Drug Conjugates Targeting Phosphatidylserine for the Treatment of Breast Cancer

7.项目摘要/摘要 仍有一种迫切的、基本上没有得到满足的需求，即推进高度选择性和有效的 用于治疗转移性和三阴性乳腺癌的治疗药物。这项建议推进了一个 创新和有前途的战略集中在首次合成和评价倍他波迪-药物结合物 (BDC)，其特征是以磷脂酰丝氨酸(PS)为靶标的工程蛋白(称为β-β)。PS 选择性地暴露在癌细胞和血管内皮细胞质膜的外叶上 肿瘤微环境，但仅限于正常细胞质膜的内叶。这 为选择性靶向有效的小分子抗癌药物(KGP18)提供了绝佳的机会 和KGP156)对肿瘤微环境的影响。腹肌更小，可以更好地穿透肿瘤 与之前评估的PS选择性抗体相比，PS选择性抗体的分布较差 脉管系统。BDC的设计是通过酶选择性地在细胞外释放KGP18和KGP156 (组织蛋白酶B、尿激酶型纤溶酶原激活物和纤溶酶)上调和/或表现为 乳腺癌细胞和相关肿瘤血管的活性增强。KGP18和KGP156强效 微管蛋白聚合的抑制剂，并表现出双重作用机制 抗增殖剂(在低Nm到Pm范围内的细胞毒性)和作为深度有效的血管破坏 这些药物对肿瘤相关的血管系统造成不可逆转的损害，最终导致肿瘤坏死。 这些基于苯并琥珀烯的合成有效载荷(KGP18和KGP156)将在比较研究中进行评估 对单甲基金葡胺E(MMAE)，它是许多临床相关抗体药物的有效载荷 共轭关系。应该注意的是，VDA在力学上不同于研究得很好的血管生成。 抑制剂。将对两个单独的交付策略进行调查。KGP18和KGP156将综合 功能化，以不同的、蛋白酶选择性的基于多肽的连接物呈现药物连接物前药结构 在被肿瘤微环境中高水平存在的特定蛋白酶切割之前生物上是惰性的， 从而选择性地释放有效有效载荷(KGP18或KGP156)。在第二个战略中，BDC将做好准备 从最好的药物-蛋白酶选择性连接子构建。假设是经过适当设计的药物连接物 构造及其对应的BDC绑定到这些高度有效的有效载荷(KGP18或KGP156)将 表现出对肿瘤血管和肿瘤细胞的高选择性。药代动力学研究将评估 效应剂药物从其相应的构造物和结合物中释放。它的有效性和选择性 这些药物连接物和BDC将使用基于细胞的研究和已建立的小鼠进行评估 原位乳腺癌模型(MDA-MB-231人异种移植瘤和同基因4T1肿瘤)。总而言之，它是 预计每一种策略都将导致肿瘤特异性药物传递和强大的抗肿瘤活性。

7. Project Summary/Abstract There remains an urgent, and largely unmet need for the advancement of highly selective and effective therapeutic agents for the treatment of metastatic and triple negative breast cancer. This proposal advances an innovative and promising strategy focused on the first time synthesis and evaluation of betabody-drug conjugates (BDCs), which feature engineered proteins (referred to as betabodies) that target phosphatidylserine (PS). PS is selectively exposed on the outer leaflet of the plasma membrane of cancer cells and endothelial cells in the tumor microenvironment, but is confined to the inner leaflet of the plasma membrane of normal cells. This provides an exquisite opportunity for selective targeting of potent small-molecule anticancer payloads (KGP18 and KGP156) to the tumor microenvironment. Betabodies are smaller allowing for better tumor penetration compared with previously evaluated PS-selective antibodies, which demonstrated poor distribution beyond the vasculature. BDCs are designed to selectively release KGP18 and KGP156 extracellularly by enzymes (cathepsin B, urokinase-type plasminogen activator, and plasmin) that are upregulated and/or demonstrate enhanced activity by breast cancer cells and associated tumor vasculature. KGP18 and KGP156 are potent inhibitors of tubulin polymerization and demonstrate dual mechanism of action functioning as remarkably active antiproliferative agents (cytotoxicity in low nM to pM range) and as profoundly effective vascular disrupting agents, which impart irreversible damage to tumor-associated vasculature ultimately leading to tumor necrosis. These synthetic benzosuberene-based payloads (KGP18 and KGP156) will be evaluated in comparative studies to monomethyl-auristatin E (MMAE), which is a payload of choice in many clinically relevant antibody-drug conjugates. It should be noted that VDAs are mechanistically distinct from the well-studied angiogenesis inhibiting agents. Two individual delivery strategies will be investigated. KGP18 and KGP156 will be synthetically functionalized with distinct, protease-selective peptide-based linkers rendering the drug-linker prodrug constructs biologically inert until cleaved by specific proteases that are present at high levels in the tumor microenvironment, thus selectively releasing the potent payload (KGP18 or KGP156). In a second strategy, BDCs will be prepared from the best drug-protease selective linker constructs. The hypothesis is that appropriately designed drug-linker constructs and their corresponding BDCs tethered to these highly potent payloads (KGP18 or KGP156) will demonstrate high selectivity for tumor vasculature and tumor cells. Pharmacokinetic studies will evaluate the release of the effector drugs from their corresponding constructs and conjugates. The efficacy and selectivity of these drug-linker constructs and BDCs will be evaluated using cell-based studies and established murine orthotopic breast cancer models (MDA-MB-231 human xenografts and syngeneic 4T1 tumors). In summary, it is expected that each strategy will result in tumor-specific drug delivery and potent anti-tumor activity.