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

 描述(申请人提供)：由于缺乏合适的口服给药剂型，主要是由于药物的溶解性和渗透性不足，疾病的发病率和进展变得更加繁重。癌症化疗尤其如此。因此，注射剂型的使用具有更大的毒性、患者不适感、使用复杂性和相关的医疗成本。转运体靶向口服给药策略在制药工业中特别重要，因为最近药物发现的化学空间正趋向于更亲水的新化学实体，主要是因为观察到的毒性和CYP介导的药物与亲脂药物的相互作用。因此，前药策略已被用来克服药物的不良物理化学性质，并提高口服生物利用度。特别是，许多研究都涉及使用氨基酸酯前药来改善抗病毒和抗癌药物的递送。然而，很少有人关注激活过程，特别是使用基于活性的蛋白质图谱作为一种工具来识别小分子底物中负责水解酰胺、酯和硫酯键的丝氨酸水解酶(SHS)。显然，需要新的范例来改善极性(即BCS III类)治疗剂的肠道吸收和生物利用度，并在人体试验之前将这些发现转化为相关的动物模型。因此，这项赠款申请的长期目标是开发对癌症患者有效的口服前药。我们的工作假设是，在人源化小鼠中以PEPT1为靶点的方法，结合化学蛋白质组激活前体药物的策略，将有效地产生口服TE抗癌化合物吉西他滨的新型前体药物。为了验证这一假设，提出了以下具体目标：目的1.在PEPT1人源化的小鼠模型中表征前药valacylovir的肠道通透性和口服吸收，并确定人和小鼠PEPT1同源物之间是否存在物种差异，目的2.利用先进的基于活性的蛋白质谱(ABPP)蛋白质组学方法测定肠道和肝脏中丝氨酸水解酶的前药结合蛋白表达，目的3.确定吉西他滨前药的转运和激活途径，以开发口服给药的癌症化合物。通过结合分子、遗传、基于活性的蛋白质图谱和对人源化(和转基因)小鼠的整体动物研究，拟议的研究将极大地促进我们对hPEPT1靶向摄取和激活酯前体药物以及开发新的口服可用化合物治疗癌症的理解。

 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.