Novel Transport and Activation Strategy to Improve the Bioavailability of Targeted Prodrugs

 描述（由申请人提供）：由于缺乏合适的口服剂型，主要是由于药物的溶解度和渗透性不足，导致疾病发病率和进展更加繁重。对于癌症化疗来说尤其如此。因此，施用的可注射剂型具有更大的毒性、患者不适、使用复杂性和相关的医疗保健成本的风险。用于口服药物递送的转运蛋白靶向策略在制药工业中尤其重要，因为最近药物发现努力的化学空间正趋向于更亲水的新化学实体，主要是因为在亲脂性药物中观察到的毒性和CYP介导的药物-药物相互作用。因此，前药策略已被用于克服药物的不期望的物理化学性质，并改善口服生物利用度。特别地，许多研究已经解决了氨基酸酯前药用于改善抗病毒剂和抗癌剂的递送的用途。然而，很少有人关注的激活过程，特别是，使用基于活性的蛋白质分析作为一种工具，用于确定丝氨酸水解酶（SH）负责水解小分子底物中的酰胺，酯和硫酯键。显然需要新的范例来改善极性化合物的肠吸收和生物利用度（即，BCS III类）治疗剂，并在人体试验之前在相关动物模型中转化这些发现。因此，该资助申请的长期目标是开发有效治疗癌症患者的口服前药。我们的工作假设是，在人源化小鼠中的PEPT 1靶向方法，结合用于前药活化的化学蛋白质组学策略，将有效地产生用于口服给药抗癌化合物吉西他滨的新型前药。为了验证这一假设，提出了以下具体目标：目标1.表征前药伐昔洛韦在PEPT 1人源化的小鼠模型中的肠渗透性和口服吸收，并确定人和小鼠PEPT 1直系同源物之间是否存在种属差异，目标2。使用先进的“基于活性的蛋白质谱分析”（ABPP）的质谱蛋白质组学和目的3，确定丝氨酸水解酶在肠和肝中的前药结合蛋白表达。确定吉西他滨前药的转运和活化途径，用于开发口服抗癌化合物。通过结合分子，遗传，基于活性的蛋白质谱分析和人源化（和转基因）小鼠的整体动物研究，拟议的研究将大大推进我们对hPEPT 1靶向摄取和酯前药活化的理解，以及开发新的口服化合物来治疗癌症。

 DESCRIPTION (provided by applicant): Disease morbidity and progression are made more burdensome by the lack of a suitable dosage form for oral administration, primarily because of inadequate solubility and permeability properties of the drug. This is especially true for cancer chemotherapy. As a result, injectable dosage forms are administered which has greater risks of toxicity, discomfort to the patient, complexity of use and associated health care costs. Transporter-targeting strategies for oral drug delivery are especially important in the pharmaceutical industry since the chemical space of recent drug discovery efforts is trending toward more hydrophilic new chemical entities, primarily because of the toxicity and CYP-mediated drug-drug interactions observed with lipophilic drugs. Thus, prodrug strategies have been utilized to overcome undesirable physical-chemical properties of the drug, and to improve oral bioavailability. In particular, many studies have addressed the use of amino acid ester prodrugs for the improved delivery of anti-viral and anti-cancer agents. However, little attention has focused on the activation process and, in particular, the use of activity-based protein profiling as a tool for identifying the serine hydrolases (SHs) responsible for hydrolyzing amide, ester and thioester bonds in small molecule substrates. It is clear that new paradigms are needed to improve the intestinal absorption and bioavailability of polar (i.e., BCS Class III) therapeutic agents, and to translate these findings in a relevant animal model prior to testing in humans. Thus, the long-term objectives of this grant application are to develop orally administered prodrugs that are effective in treating cancer patients. Our working hypothesis is that the PEPT1-targeted approach in humanized mice, coupled to the chemoproteomic strategy for prodrug activation, will be effective in generating novel prodrugs for oral administration of te anti-cancer compound gemcitabine. To test this hypothesis, the following specific aims are proposed: Aim 1.To characterize the intestinal permeability and oral absorption of the prodrug valacyclovir in a mouse model humanized for PEPT1 and determine if a species difference exists between the human and mouse PEPT1 orthologs, Aim 2. To determine the prodrug binding protein expression of serine hydrolases in the intestine and liver using advanced "activity based protein profiling" (ABPP) mass spectrometry-based proteomics, and Aim 3. To determine the transport and activation pathways of gemcitabine prodrugs for the development of orally administrable cancer compounds. By combining molecular, genetic, activity-based protein profiling, and whole animal studies in humanized (and transgenic) mice, the proposed studies will greatly advance our understanding of hPEPT1- targeted uptake and activation of ester prodrugs and the development of new orally available compounds to treat cancer.