Therapeutics Development for Hepatic Fibrosis

描述（由申请人提供）：本提案的总体目标是开发外周选择性大麻素受体1（CB1R）拮抗剂以治疗肝纤维化。内源性大麻素系统（EC）多年来已成为肝脏疾病的关键调节因子。EC受体有两种：CB1R和CB2R。它们在中枢神经系统（CNS）和某些外周组织中表达。虽然这些GPCR在正常肝脏中少量表达，但它们在损伤或疾病时上调。功能研究表明，CB1R和CB2R在肝纤维化中具有相反的作用。虽然CB1R活化是促纤维化的，但CB2R活化是抗纤维化的。因此，CB1R的遗传或药理学阻断已被证明在各种临床前模型中抑制肝脏疾病，并且该受体是药物开发的靶点。不幸的是，CB1R的非组织选择性拮抗剂在人类中产生不利的精神作用，并且不适合长期使用。然而，新出现的临床前证据表明，靶向外周表达的CB1R是治疗肝脏和代谢疾病的一种令人兴奋的新策略。在过去的几年里，我们的团队已经成功地参与了外周选择性CB1R拮抗剂的开发，生产出了CB1R化合物，其对CNS的渗透率<7%，具有约10 nM的效力，对CB1R的选择性是CB2R的50倍以上，并且口服吸收具有合理的半衰期。预计通过R01申请对这些拮抗剂的进一步改进将产生用于IND使能研究的化合物。提出了四个具体目标。通过目标1，二苯基嘌呤CB1R拮抗剂支架的改进将继续产生具有甚至更低CNS渗透（<2%）的化合物。通过目标2，这些化合物将在体外进行初步表征，以确定其效力、选择性、毒性和代谢稳定性。将在体内测试所选化合物以建立其药代动力学（PK）特征，并使用一系列行为测试排除中枢CB1R的拮抗作用。通过目标3，候选化合物将在两种完善的肝纤维化模型中测试其消除疾病进展的功效。还将评价几种表型和分子疾病相关生物标志物，以评价疗效程度。通过目标4，将在行为啮齿动物强迫游泳试验中测试高级先导化合物，以确定长期给药诱导的任何潜在精神不良反应。总之，该项目的成功完成将产生用于临床开发的新型化合物，以治疗肝纤维化，这是一个迫切需要的领域。

DESCRIPTION (provided by applicant): The overall goal of this proposal is to develop peripherally selective cannabinoid receptor 1 (CB1R) antagonists to treat hepatic fibrosis. The endocannabinoid system (EC) has emerged over the years as a key regulator of hepatic diseases. There are two accepted EC receptors - CB1R and CB2R. They are expressed in the central nervous system (CNS) and certain peripheral tissues. While these GPCRs are marginally expressed in the normal liver, they are up-regulated upon injury or disease. Functional studies indicate that CB1R and CB2R have opposing roles in liver fibrosis. While CB1R activation is pro-fibrotic, CB2R activation is anti-fibrotic. Accordingly, genetic or pharmacological blockade of CB1R has been demonstrated to inhibit liver disease in various preclinical models and the receptor is a target for medications development. Unfortunately, non-tissue-selective antagonists of CB1R produce adverse psychiatric effects in humans and are not suitable for chronic use. However, emerging preclinical evidence suggests that targeting peripherally expressed CB1R is an exciting new strategy for treating hepatic and metabolic disorders. Our group has been successfully involved in the development of peripherally selective CB1R antagonists over the last couple of years having produced CB1R compounds that have <7% penetration into the CNS, have ~10 nM potency, are >50-fold selectivity for CB1R over CB2R, and are orally absorbed with reasonable half-lives. It is expected that further refinement of these antagonists through this R01 application will produce compounds for IND-enabling studies. Four specific aims are proposed. Through aim 1, refinement of a diphenyl-purine CB1R antagonist scaffold will continue to produce compounds that have even lower CNS-penetration (<2%). Through aim 2, these compounds will be pharmacologically characterized in vitro to determine their potency, selectivity, toxicity, and metabolic stability. Selected compounds will be tested in vivo to establish their pharmacokinetic (PK) profile and to rule out antagonism of central CB1R using a battery of behavioral tests. Through aim 3, candidate compounds will be tested for efficacy in two well-established models of liver fibrosis for abrogation of disease progression. Several phenotypic and molecular disease-relevant biomarkers will be evaluated as well to evaluate degree of efficacy. Through aim 4, advanced lead compounds will be tested in a behavioral rodent forced-swim assay to identify any potential psychiatric adverse effects induced by chronic dosing. Taken together, successful completion of the project will produce novel compounds for clinical development to treat hepatic fibrosis, which is an area of urgent need.