Secretin

作者｜Dr. Yi YangPrincipal Scientist, 丹麦辉凌制药整理排版｜药研制药业从诞生之初就在不断寻求天然产物赐予的机遇。包括植物（根、树皮、叶子）、微生物（陆地和海洋）、毒素、毒液和其他天然生物来源为制药业的形成、发展与壮大提供了取之不竭的宝贵源泉。在当前开发针对 COVID-19 的药物和疫苗的竞赛中，天然产物或衍生物同样奉献了宝贵的工具。然而天然化合物的专利申请却是一件比较复杂的事情，尤其是在美国分子病理学会 (Association for Molecular Pathology) 2012年诉讼Myriad Genetics Inc. 闹得沸沸扬扬之后 (美国最高法院最终裁决，仅仅分离自然界中发现的基因并不能使它们获得专利)，对于天然化合物的专利立法在美国发生了重大变化，如今在美国为天然化合物申请专利变得非常困难。为了使天然产品获得专利，它必须（像任何其他发明一样）是新颖的的和具有创造性的。新颖性和创造性是专利申请中必须呈现的元素。在天然化合物是否可以申请专利保护这一问题上，欧洲与美国有着不同的政策。根据《欧洲专利公约》第 27(a) 条，如果生物技术发明涉及“从自然环境中分离出来或通过技术工艺生产的生物材料，即使它以前在自然界中存在”，它们也可以申请专利。例如，根据欧洲法律，专利可能授予从天然植物中以自然界中不存在的形式分离的特定提取物。欧洲专利局的审查指南解释说，“发现自然界中存在的一种以前未被认可的物质……如果仅仅是发现，那么它将不具有专利性。但是，如果可以证明自然界中发现的物质产生的技术效用，它是具有可申请专利的可能性的。这种情况的一个例子是自然界中发现的具有抗生素作用的物质。“这引入了进一步的“效用”要求，即天然产品必须产生技术效果并因此是有用的。这种“实用”技术效果不需要是新的，只要天然产品以前没有从其自然环境中分离出来，因此本身就是一种新颖的产品。该指南的解释意味着，只要物质之前没有从自然环境中分离出来并且具有有用的效果，物质来源于自然这一简单事实本身并不能阻止它在欧洲获得专利。显然，对于天然化合物的可专利性，欧洲比美国宽容得多。在著名的Myriad判决中，美国最高法院裁定（在天然DNA 片段的背景下）“天然 DNA 片段是自然的产物，并不能仅因为它已被分离而就被认定符合专利条件，但 cDNA 是专利符合条件的，因为它不是自然发生的”。此后，美国专利商标局通常会拒绝对天然产品的权利要求。因此，在 Myriad 判决之后，那些可能无法在美国获得专利保护的天然产品却有机会在欧洲获得专利。尽管有这相对宽松的“红头文件”，但在现实中，事情通常没有那么非黑即白的明了。例如仅仅声明一种成分是“天然的”，如此简单的“标签“通常会造成似是而非的效果，并且可能无法单独提供可专利性。作为天然产物申请专利的必要条件之一是，天然产物必须是第一次真正天然并且实现了真正的分离，以及具有明确定义。例如在许多情况下，化妆品、个人护理产品、食品和膳食补充剂含有已知多年（有时甚至是上千年）的天然成分，这意味着不可能将天然成分作为一种已分离的化合物申请专利。此外，为了满足天然产物产生有用效果的要求，提交的专利申请应该包括支持数据，以合理地证明这种效果。对于化妆品或个人护理产品，这种效果可以是减少皱纹或瑕疵的出现，或改善皮肤水合作用。对于食品或膳食补充剂，效果可能是改善健康或营养。最后，专利申请公开是对可专利性的另一个要求。专利必须以足够清晰和完整的方式公开发布，专利申请的技术内容必须具有可重复性。对于第一次从自然环境中分离出来的天然产物，专利应公开分离该天然产物的具体方法。总之，欧洲法律可能允许对首次分离的天然产物授予专利，而此类产品在美国可能没有资格获得专利保护。然而，专利申请需要令人信服的证据证明天然产品产生了有用的技术效果，以及分离产品的方法的细节。由于欧洲专利局对优先权和附加主题的严格评估，所有主题都应该包含在该发明的首次申请中。相反，美国专利商标局（USPTO）采取了更加有力的方法来排除天然生物化合物。根据专利法第 101 条，分离的蛋白质和肽可能属于“天然产品”的范畴，如果没有更多的特质，则可能不是可授予专利。根据美国专利商标局的指导方针，分析的重点是要求保护的产品与天然形式相比是否具有“明显不同的特征”。这为通过制剂的方式赋予产品特殊性质，从而具备申请专利保留了一种可能。对于多肽和蛋白类的物质，突破天然化合物在美国的专利保护瓶颈，可以通过改性的方式对于其一级结构进行调整，使得它们在身份上与“天然产品”分道扬镳。这些改性包括一级结构的变化，即氨基酸残基序列的改变，例如将N-或C-端非关键的氨基酸序列从原始的天然多肽中排除。也可以进行结构修改，例如进行氨基的脂肪酸酰胺化，这在很多GLP-1的多肽药物中得到了展示，例如semaglutide。更常见的结构修饰是N-端乙酰化和C-端酰胺化。这些结构改变不仅能够使得多肽摆脱天然化合物的身份标签，更重要的是，它们能够改变多肽的电荷，增强多肽分子的化学稳定性和改善药代动力学特征。在美国、欧洲和日本上市的多肽药物以及诊断试剂中，大约有30%的个体为天然多肽化合物，但距离最近的一次审批是2017年的治疗低血压导致的败血性休克的angiotensin II (血管紧张素II, 商品名Giapreza®)。而angiotensin II之前的上市天然多肽药物是2009年通过审批的Romidepsin（罗米地辛，商品名Istodax®，图2），是一种用于皮肤 T 细胞淋巴瘤 (CTCL) 和其他外周 T 细胞淋巴瘤 (PTCL) 的抗癌剂。罗米地辛是一种从紫色色杆菌中提取的天然产物，通过阻断组蛋白脱乙酰酶起作用，从而诱导细胞凋亡。图1. Angiotensin II化学结构图2. Romidepsin化学结构从多肽药物的分子设计角度来看，尽管绝大多数的上市多肽都是建立在天然化合物多肽的基础之上，但天然多肽分子本身成药的例子在进入21世纪后仅发生过7次（aviptadil 2000年，nesiritide 2001年，secretin porcine，诊断试剂，2002年， daptomycin 2003年， ziconotide 2004 年，romidepsin 2009年， angiotensin II 2017年），而在Myriad判决之后仅出现过一次（angiotensin II）。由此可见，开发多肽药物的制药公司应该已经找到了针对天然化合物极难在美国申请专利的方案，即通过改性多肽的手段保护自己的知识产权，无论从专利的角度，还是改善多肽药代动力学特性的方面，都起到积极的作用。这意味着天然产物提供来源，但不是最终方案。------------THE END------------点击查看：投稿获丰厚稿费关注药研 一路同行药研论坛：始终以为药品研发一线人员提供高质量、高性价比培训为第一宗旨。自成立以来，累计举办50余期药品研发、注册领域研讨班。据统计，中国医药工业百强企业和研发百强企业均超过90%参加过药研收费类培训。截至2021年底，包括上海强生、辉瑞、阿斯利康、山德士、日本大冢、大鹏、卫材、小林制药、扬子江、恒瑞、正大天晴、东阳光、科伦、中科院等在内的2000余家企事业单位参加过药研线下收费培训，得到业界普遍认可与好评！药研学院：已同众多企业合作70余期直播课，全网观看突破100万+，药研直播课聚焦药品研发相关主题，平均观看人数行业领先。药研自媒体矩阵20万+：目前药研公众号研发领域关注用户约10万人！双直播平台10万人，微信社群5万人，其中制药企业和研发机构关注量4000+。商务合作：15911172616

Every week there are numerous scientific studies published. Here’s a look at some of the more interesting ones. How Prions Replicate and Implications for Alzheimer’s and Parkinson’s Prions are misfolded proteins that are associated with rare and fatal diseases, such as bovine spongiform encephalopathy (BSE or “mad cow disease”) in cattle and Creutzfeldt-Jakob Disease (CJD) in humans. Misfolded proteins have also been implicated in a number of other human neurological diseases, including Alzheimer’s, Parkinson’s and Huntington’s. Researchers at Case Western Reserve University who were studying prions, for the first time identified surface features of human prions that allows them to replicate in the brain. This may have significant implications for a range of neurodegenerative diseases. They published their research in the journal PLOS Pathogens. “Human prion diseases are conceivably the most heterogeneous neurodegenerative disorders, and a growing body of research indicates that they are caused by distinct strains of human prions,” said Jiri Safar, professor of pathology, neurology and neurosciences at Case Western, who led the research. “However, the structural studies of human prions have lagged behind the recent progress in rodent laboratory prions, in part because of their complex molecular characteristics and prohibitive biosafety requirements necessary for investigating disease which is invariably fatal and has no treatment.” To identify this, they developed a new three-step process involving high-intensity synchrotron x-ray beams, rapid chemical modifications of prions by short bursts of light and anti-prion antibodies, and prion replication in a test tube. They believe that this structural approach will provide a template for identifying structurally important locations on misfolded proteins in other diseases like Alzheimer’s. In Alzheimer’s, for example, proteins move from cell to cell in a fashion similar to prions. Unexpected Finding: Inflammatory Proteins Might Slow Cognitive Decline Scientists with Massachusetts General Hospital (MGH) and the Harvard Aging Brain Study (HABS) found an unexpected discovery about the relationship between inflammation and Alzheimer’s disease. It has long been believed that neuro-inflammation is associated with Alzheimer’s disease. But this new research suggests that elevated levels of two inflammatory cytokines are linked to slower cognitive decline in aging adults. Most research has suggested, including that of this study’s co-senior author Rudolph Tanzi, vice chair of Neurology and co-director of the Henry and Allison McCance Center for Brain Health at MGH, that people with Alzheimer’s and other dementias have elevated levels of certain cytokines. The idea was to determine why some people have amyloid in their brains but don’t seem to be affected, while other people undergo cognitive decline. They found that people with significant amyloid-beta levels in their brains but also had high levels of a pro-inflammatory cytokine, interleukin 12 (IL-12), showed little cognitive decline. But if people with increased amyloid had lower IL-12 levels, they underwent more cognitive decline. And high levels of IL-12 were also associated with fewer tau tangles, another abnormal protein found in the brains of Alzheimer’s patients. Another pro-inflammatory cytokine, interferon-gamma (IFN-gamma), was associated with slower cognitive decline when its levels were elevated, whether a person had amyloid deposits or not. Tanzi believes that, although it seems counterintuitive, the higher levels of inflammation-inducing proteins might mean their immune systems were better primed to fight infections. mRNA Vaccine Developed Against Malaria Researchers at Walter Reed Army Institute of Research (WRAIR), the Naval Medical Research Center, the University of Pennsylvania and Acuitas Therapeutics, developed an mRNA vaccine that works against malaria in animal models. Like the mRNA vaccines against COVID-19, it uses a segment of mRNA in a lipid nanoparticle that teaches cells to code for circumsporozoite protein, which triggers an immune response against malaria. In mice, the vaccine created high levels of protection. The most advanced malaria vaccine is dubbed RTS,S, which was developed in partnership with WRAIR, but it has some limitations. There is limited sterile efficacy and duration of protection. However, both depend on P. falciparum’s circumsporozoite protein to create an immune response. The hope is that the mRNA vaccine will provide a stronger and more durable immune response, partly by controlling the degradation of the circumsporozoite protein in the body. Secretin Hormone Activates Brown Fat, Inducing Satiation Scientists from the University of Turku discovered a new mechanism that controls satiation, the feeling of being full after eating. The hormone secretin stimulates satiation by activating brown adipose (fat) tissue. Brown fat generates heat in response to cold exposure and is associated with normal weight and glucose metabolism in addition to lower risks for cardiovascular diseases. Previous studies show that meals increase thermogenesis in brown fat, but its significance wasn’t clear. Now they find that secretin, a hormone, is dumped into the blood by the intestines, and stimulates the production of peptic juices in the pancreas when we eat. Their research found secretin receptors in the brown adipose tissue of healthy people, and secretin infusions increased glycose uptake in brown fat tissue, and elevated energy expenditure in the whole body. It also decreased the activity of the reward system in the brain, with subjects showing decreased appetite and longer times between meals. New Insight into How the Brain Controls the Body’s Sugar Levels Investigators with Baylor College of Medicine discovered a new mechanism in part of the brain that regulates blood sugar levels throughout the body without affecting body weight. Within the hypothalamic region of the brain, an area called the ventromedial nucleus of the hypothalamus (VMH) has glucose-sensing neurons and regulates glucose metabolism in peripheral tissues. They identified a molecular pathway in the VMH that mediates whole-body glucose balance. This also involves Rap1, an enzyme that mediates overnutrition-associated disorders. They found that activating Rap1 exaggerated the high blood sugar levels in diet-induced obesity mouse model; genetic loss of hypothalamic Rap1 dropped the blood sugar levels, as well as insulin levels, and improved glucose and insulin tolerance. But these changes in sugar levels didn’t result in changes in body weight, which suggested a primary role of Rap1 in glucoregulatory function. Inhibiting the Master Switch in Various Lymphomas Researchers at Icahn School of Medicine at Mount Sinai developed a type of drug that turns off a master switch involved in most cases of a fatal form of lymphoma. These are small-molecule inhibitors of the SOX 11 oncogene and are toxic to mantle cell lymphoma (MCL), a fatal subtype of non-Hodgkin’s lymphoma. They screened more than 12 million compounds at the SOX 11 surface that interact with DNA and identified several small molecules that were predicted to affect the SOX 11-DNA interaction, resulting in blocking the mechanism by which MCL develops. “The SOX 11 protein, which is expressed by up to 90% of mantle cell lymphoma patients, is an attractive target for therapy,” said senior author Samir Parekh, Professor of Medicine (Hematology and Medical Oncology), at Icahn School of Medicine at Mount Saini. “But until now, no small-molecule inhibitor had been identified. We discovered three structurally related compounds which are able to bind to the oncogene, perturb its interaction with DNA and, through their anti-MCL cytotoxicity, actually kill lymphoma cells with remarkable efficiency.”