Small Molecule E6 Inhibitors to Treat Dysplasia Caused by HPV Infections

人乳头瘤病毒（HPV）引起非常常见的皮肤和组织感染， 粘膜上皮感染特定的“高危”HPV基因型可进展至 称为发育不良的恶性病变，经过数年的时间，可能最终导致侵袭性和 转移性上皮恶性肿瘤。我们的治疗目标是治疗早期感染， 子宫颈，生殖器和肛门，折磨数百万妇女和男子之前，这些进展到侵入性 癌的 Kovenant Therapeutics的策略是通过选择性靶向E6来消除HPV感染。 蛋白质，并阻止其与细胞结合伴侣的相互作用。E6是病毒所必需的 基因组复制和维持，并且总是在HPV相关的发育不良中表达， 恶性肿瘤我们对化学文库进行了计算机筛选，寻找小分子， 类似于E6与其几个细胞伙伴的界面。我们的分析集中在 E6与泛素连接酶E6 AP的蛋白质-蛋白质相互作用，E6 AP介导泛素化， 蛋白酶体介导的肿瘤抑制蛋白p53的破坏。利用这个模型，我们 设计和合成的化合物，1）与HPV-16 E6结合，2）装备有“弹头”， 与HPV-16 E6结合口袋中的特异性半胱氨酸形成共价键，用于E6 AP。的 识别配备有反应性弹头的分子的方法，这些弹头介导共价和 与半胱氨酸的不可逆结合在几种新的临床上可获得的药物中得到了例证， 以前被认为是不可用的蛋白质。我们发现了几种化合物 通过该半胱氨酸残基与E6结合，阻断E6与E6 AP的相互作用，恢复P53功能，并诱导 HPV-16表达细胞死亡。多种生化分析，包括X射线晶体学 证明这些抑制剂占据靶向E6口袋并与该半胱氨酸形成单一加合物。 由共晶数据引导的迭代优化使得能够设计和合成>80个新颖的 化合物，并产生具有增加的活性的化学型。为期一年的第一阶段SBIR 一项提案计划筛选我们现有的E6抑制剂收集，以确定其生物活性 在基于细胞的测定和药代动力学特性中， 剂我们会展开药物开发研究，包括局部应用的配方， 早期药代动力学和毒理学表征。I期研究的成功将 验证这种抗病毒策略，并使我们能够继续申请第二阶段SBIR， 国家研究开发扶持性研究。

Human papillomaviruses (HPV) cause exceedingly common infections of cutaneous and mucosal epithelia. Infection with specific “high risk” HPV genotypes can progress to pre- malignant lesions called dysplasias, which over a period of years, can eventuate in invasive and metastatic epithelial malignancies. Our therapeutic goal is to treat early stage infections of the cervix, genitalia, and anus that afflict millions of women and men before these progress to invasive cancers. Kovina Therapeutics strategy is to eliminate HPV infection by selectively targeting the E6 protein and preventing interactions with its cellular binding partners. E6 is necessary for viral genome replication and maintenance and is always expressed in HPV-associated dysplasia and malignancies. We performed in silico screening of chemical libraries for small molecules that would resemble the interface of E6 with several of its cellular partners. Our assays focused on the protein-protein interaction of E6 with the ubiquitin ligase E6AP, which mediates ubiquitination and proteasome mediated destruction of the tumor suppressor protein p53. Using this model, we designed and synthesized compounds that 1) bind to HPV-16 E6 and 2) are armed with a ‘warhead’ to make a covalent bond with a specific cysteine in HPV-16 E6 binding pocket for E6AP. The approach to identify molecules equipped with reactive warheads that mediate covalent and irreversible binding to cysteine is exemplified in several new clinically available drugs that target proteins previously considered undruggable. We discovered several compounds covalently bound to E6 via this cysteine residue, block E6 interaction with E6AP, restore P53 function, and induce death of HPV-16 expressing cells. Multiple biochemical analyses including X-ray crystallography prove these inhibitors occupy the targeted E6 pocket and form a single adduct with this cysteine. Iterative optimization guided by the co-crystal data enabled design and synthesis of >80 novel compounds and has resulted chemotypes with increased activity. This one-year Phase I SBIR proposal plans to screen our existing E6 inhibitor collection to determine their biological activities in cell-based assays and pharmacokinetic properties that would meet FDA guidelines for a topical agent. We will initiate drug development studies including formulation for topical application and early stage pharmacokinetic and toxicology characterization. The success of Phase I study will validate this antiviral strategy and position us to proceed to apply for a Phase II SBIR to perform IND-enabling studies.