GGCX

第一性原理计算解决50年悬而未决难题：半导体中铜为何扩散更快？ Ab initio及第一性原理入门参考书介绍 《海贼王》告诉你，做科研为什么不能闭门造车…… 来自公众号：小柯生命 本文以传播知识为目的，如有侵权请后台联系我们，我们将在第一时间删除。 北京时间2025年1月30日，美国德克萨斯大学西南医学中心（UT Southwestern Medical Center）的齐晓峰实验室在Nature发表了题为“Structure and mechanism of vitamin-K-dependent γ-glutamyl carboxylase”的研究论文。 该工作解析了GGCX处于不同状态的冷冻电镜结构，揭示了GGCX的催化机理，并且发现了胆固醇（Cholesterol）对GGCX的关键调节作用。 维生素K（VK）是一种不可或缺的脂溶性维生素。在人体内，内质网膜蛋白γ-谷氨酰羧化酶（γ-glutamyl carboxylase, GGCX）是唯一已知的利用VK作为辅因子（co-factor）的酶。GGCX可以通过氧化VKH2（还原态的VK），将VK依赖蛋白（VK-dependent proteins，VDPs）中特定的谷氨酸（Glu）残基羧基化，使其变成g-羧基谷氨酸（Gla）。目前已知的VDPs包括凝血因子II、VII、IX、X、骨钙素（Osteocalcin，也称为Bone Gla Protein，BGP）、基质Gla蛋白（Matrix Gla protein，MGP）、生长停滞特异性蛋白6（Growth arrest-specific 6，Gas6）等，它们参与凝血、骨骼形成、组织钙化、生长发育等多种生物学过程。由于羧基化对VDPs的功能至关重要，VK缺乏或者GGCX突变则会导致与VDPs相关的疾病,然而GGCX利用VK完成VDP羧基化的分子机理依然不清楚。 VDPs的N端含有一个“前肽（Propeptide）”片段，它可以引导VK依赖蛋白结合GGCX并且具有激活GGCX的功能。为了揭示Propeptide激活GGCX的机理，作者比对了GGCX在apo和BGP结合状态下的结构，Propeptide结合在GGCX内质网腔结构域的两个亚结构域之间，该结合引发了GGCX内质网腔结构域的构象变化，使其结合并稳定了跨膜螺旋TM6和TM7。稳定后的TM6和TM7和TM5，TM8一起形成了一个底物结合口袋，该口袋开口朝向内质网膜。由于VK是一个脂溶性分子，作者推断该口袋可能是VK结合位点。 为验证猜想，作者在表达GGCX-BGP复合物时加入MK-4（维生素K2亚家族成员），并解析了GGCX-BGP-MK-4的复合物结构。不出所料，VK结合在TM6和TM7形成的口袋中。这一发现揭示了Propeptide激活GGCX的机理，即Propeptide结合稳定了GGCX并使其形成VK结合口袋，而没有Propeptide结合的情况下，GGCX无法结合VK。随后，作者分析了位于GGCX内质网腔结构域底部的催化中心。BGP的Glu残基从内质网腔结合到催化中心，而VK从内质网膜进入催化中心。GGCX中His160、Ile296、Phe299、Met401和Met402等残基在结合Glu和VK中发挥重要作用，而Lys218残基则负责VKH2去质子化，促使羧化反应的发生。 有意思的是，GGCX的跨膜区特异结合了一个胆固醇分子。为了研究胆固醇对GGCX的调节作用，作者使用了UT-2细胞系，该细胞因缺乏胆固醇合成通路里的关键限速酶HMG-辅酶A还原酶（HMG CoA Reductase，HMGCR）而无法合成胆固醇。通过调节细胞培养基中胆固醇的含量，作者成功在UT-2细胞的内质网上建立了可控的胆固醇浓度梯度。利用该实验体系，作者发现GGCX蛋白水平随着胆固醇的浓度呈显著正相关。进一步的分子动力学模拟实验（MD simulation）显示胆固醇分子可以提高GGCX结构的稳定性。这些结果证明了胆固醇通过稳定GGCX结构来调节其在细胞中的蛋白水平。 结合作者之前HMGCR和UBIAD1（UbiA prenyltransferase domain containing 1）相关的研究工作，作者提出了GGCX的催化和调节模型：新合成的GGCX蛋白在胆固醇的帮助下完成跨膜区的正确折叠，VDPs的结合则进一步稳定GGCX，促使VK结合口袋的形成，随后VK从内质网膜进入结合口袋，在氧气和二氧化碳的参与下，羧化反应发生。其中UBIAD1具有双重功能，它既可以阻止HMGCR降解从而促进胆固醇合成，又可以把VK1转化成VK2调节VK在不同组织中的分布。此项工作将胆固醇和VK两个重要分子联系在一起，而胆固醇和VK两个分子之间的关联与互作值得进一步的研究。 德克萨斯大学西南医学中心分子生物学系（Molecular Biology）助理教授齐晓峰博士为本文的通讯作者，分子遗传学系（Molecular Genetics）博士后王嵘为本文的第一作者。分子遗传学系Michael Brown教授和Joseph Goldstein教授（两人同为1985年诺贝尔生理与医学奖得主），以及李晓淳教授（齐晓峰博士的博士后导师）为该研究提供了宝贵意见和大力支持。 相关论文信息： https://www.nature.com/articles/s41586-024-08484-9 编辑 | 余   荷 排版 | 王大雪

The FDA is set to make a call on Aug. 14 on whether to approve seladelpar for the treatment of primary biliary cholangitis. Three months after spending $4.3 billion on CymaBay Therapeutics for its primary biliary cholangitis (PBC) med, Gilead Sciences has presented a fresh slice of data as a reminder of seladelpar’s potential while an FDA decision is pending. The open-label ASSURE study comprised 174 patients who had already previously participated in another study of seladelpar and who had not responded adequately to ursodeoxycholic acid (UDCA), the typical treatment for PBC. They received an oral dose of 10 mg seladelpar each day, with nearly all patients being female and also receiving UDCA treatment. A total of 148 patients completed 12 months of treatment. Of these, 70% reached the clinically meaningful composite response endpoint, Gilead explained in a presentation of the interim data in a May 18 release. Across all patients who received seladelpar, 37% experienced an average change from baseline alkaline phosphatase (ALP) level of 44%, considered a return to normal levels. Twenty patients received the selective PPAR-delta agonist for a full two years. Of these, 70% reached the response endpoint, but only 25% saw ALP normalization. Other biomarkers of liver injury were also reduced. Specifically, total bilirubin fell by 9%, gamma-glutamyl transferase by 36% and alanine aminotransferase by 25% from baseline levels. There were no treatment-related adverse events, while 4.6% of patients discontinued due to adverse events, Gilead reported. “The initial data from ASSURE further support the efficacy and safety profile of seladelpar observed across the robust development program and continue to indicate that seladelpar has the potential to be a best-in-class therapy that could help transform treatment for people living with primary biliary cholangitis,” Gilead Chief Medical Officer Merdad Parsey, M.D., Ph.D., said in the release. “The PBC community has been waiting for new treatments that help slow the progression of their liver disease as well as address difficult symptoms like pruritus that can have a significant impact on their quality of life,” Parsey added. “We are excited to offer a new option for this community as we work to bring seladelpar to people living with PBC, if approved.” Seladelpar was submitted to the FDA to treat PBC with pruritus, or itching, without cirrhosis or with compensated cirrhosis in December 2023. The rare liver disease primarily affects women over 40 and is characterized by impaired bile flow and the accumulation of bile acids in the liver, causing an elevation of liver enzymes that can be dangerous. The FDA is set to make a call on Aug. 14 on approving seladelpar for the treatment of PBC, including pruritus, in adults without cirrhosis or with compensated cirrhosis who are inadequate responders or intolerant to UDCA.

Mabwell (Shanghai) Bioscience is an innovative biopharmaceutical company with a full industrial chain layout that has developed multiple Antibody-Drug Conjugate (ADC) technology platforms. The company primarily focuses on oncology and age-related diseases, encompassing therapeutic areas such as cancer, autoimmune disorders, metabolism, ophthalmology, and infections. At the upcoming ASCO conference, the company will present the Phase I/II clinical study results of 9MW2821 for several advanced solid tumors through an oral report. 9MW2821 employs a site-specific linker-coupling technology developed in collaboration with the Shanghai Institute of Materia Medica, Chinese Academy of Science. This technology couples the MMAE toxin and, through optimizations in the coupling process, addresses common issues such as linker mismatches, avoiding problems like ADC aggregation for enhanced stability. The antibody is humanized and optimized for post-translational modifications (PTM), with a drug-to-antibody ratio (DAR) of 4. In February 2024, 9MW2821 was granted "Fast Track Designation" (FTD) by the FDA for treating advanced, recurrent, or metastatic esophageal squamous cell carcinoma. It is currently the first targeted therapy against Nectin-4 globally to reveal clinical efficacy and safety data for indications of esophageal and cervical cancer. Currently, four clinical trials involving 9MW2821 have been initiated: 1.An open, multicenter Phase I clinical study to evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of 9MW2821 in patients with advanced solid tumors, with plans to enroll 40 patients. 2.A Phase I/IIa clinical trial to assess the safety, tolerability, pharmacokinetics, and preliminary efficacy of 9MW2821 in patients with advanced solid tumors, aiming to enroll 208 patients. 3.An open, single-arm, multicenter Phase Ib/II clinical study of 9MW2821 combined with Junshi Biosciences' PD-1 monoclonal antibody, Toripalimab, evaluating safety and efficacy in patients with advanced or metastatic urothelial carcinoma, with plans to enroll 100 patients. 4.A randomized, open, controlled, multicenter Phase III clinical study comparing 9MW2821 in patients with locally advanced or metastatic urothelial carcinoma who have previously undergone chemotherapy that included platinum agents and PD-(L)1 inhibitors but are ineligible for surgical resection, planning to enroll 420 patients. Urothelial Carcinoma (UC) As of April 27, 2023, in 18 UC patients who progressed following treatment with platinum-based chemotherapy and immune checkpoint inhibitors, the dose of 1.25 mg/kg showed an Objective Response Rate (ORR) and Disease Control Rate (DCR) of 55.6% and 94.4%, respectively. As of December 5, 2023, 9MW2821 at a dose of 1.25 mg/kg in a phase II clinical trial showed ORR and DCR of 62.2% and 91.9% respectively, in the monotherapy treatment of advanced urothelial carcinoma patients. The median Progression-Free Survival (PFS) was 6.7 months, and the median Overall Survival (OS) had not yet been reached. Currently, the phase III clinical study 9MW2821-2023-CP301 of 9MW2821 monotherapy for locally advanced or metastatic urothelial carcinoma patients who have been previously treated with platinum-based chemotherapy and PD-(L)1 inhibitors has officially commenced. Furthermore, the phase I/II clinical study 9MW2821-2023-CP104 combining 9MW2821 with a PD-1 inhibitor is also progressing, with the first subject successfully enrolled. Cervical Cancer (CC)On March 16, 2024, MyWay Biotech reported positive clinical study results for their first cervical cancer study targeting Nectin-4 with an antibody-drug conjugate (ADC) at the 2024 SGO conference (First positive cervical cancer results for Nectin-4, MyWay announces clinical study 9MW2821). The Phase I/II cervical cancer cohort of 9MW2821 included patients with Nectin-4 positive recurrent or metastatic cervical cancer, who have failed platinum-based doublet chemotherapy with or without bevacizumab (a VEGF monoclonal antibody), and have been treated with no more than two lines of systemic therapy. As of September 25, 2023, within the expanded cervical cancer cohort of this study, the detection rate for Nectin-4 expression was 89.67%, with a 3+ tumor cell staining intensity detection rate of 67.82%. This cohort enrolled a total of 40 patients, with 57.5% of the participants previously treated with platinum-based doublet chemotherapy combined with bevacizumab, and 60% of participants previously having received platinum-based chemotherapy and immune checkpoint inhibitors. In terms of efficacy, under the selected dosage of 1.25 mg/kg in Phase II, the objective response rate (ORR) and disease control rate (DCR) among 37 evaluable patients were 40.54% and 89.19% respectively, with 1 case of complete response (CR, 2.70%), 14 cases of partial response (PR, 37.84%), and median progression-free survival (mPFS), median overall survival (mOS), and median duration of response (mDOR) not yet reached. Among patients with Nectin-4 3+ expression, the ORR and DCR for 26 evaluable patients were 50.00% and 92.31% respectively. For patients previously treated with platinum-based chemotherapy and immune checkpoint inhibitors, the ORR and DCR among 21 evaluable patients were 38.10% and 85.71%, respectively. Esophageal Squamous Cell Carcinoma (ESCC)As of February 20, 2024, in the phase II clinical trial of 9MW2821 at a dosage of 1.25 mg/kg, among 30 patients with advanced esophageal cancer who received monotherapy and completed at least one tumor efficacy evaluation, the objective response rate (ORR) and disease control rate (DCR) were 30% (9/30) and 73.3% (22/30), respectively. The phase II clinical study targeting esophageal cancer indications will continue to enroll and evaluate patients and will initiate phase III clinical discussions as soon as possible. In February 2024, 9MW2821 was granted Fast Track Designation (FTD) by the FDA for the treatment of advanced, recurrent, or metastatic esophageal squamous cell carcinoma (This is the first Nectin-4 ADC showing positive results for ESCC; 9MW2821 received FTD from the FDA). SafetyClinical trial results for 9MW2821 targeting advanced solid tumors were orally presented at the 2023 ESMO Congress held in Madrid, Spain, from October 20-24, 2023. As of April 27, 2023, the study had enrolled 97 patients, including 39 with urothelial carcinoma and 29 with cervical cancer. The age range of the patients was 32-78 years (median age of 57 years), and the dosage ranged from 0.33 to 1.5 mg/kg. These subjects had previous treatments with platinum-based chemotherapy and immune checkpoint inhibitors. There were no treatment-related deaths in the study. Only one case of dose-limiting toxicity was observed in the 1.5 mg/kg group, which was grade 4 neutropenia lasting more than 5 days. The maximum tolerated dose (MTD) has not yet been reached. The incidence of any grade treatment-related adverse events (TRAEs) was 64.9%. The most common treatment-related adverse events were decreased white blood cell count (36.1%, 35/97), neutropenia (35.1%), nausea (22.7%), increased aspartate aminotransferase (22.7%), rash (19.6%), hair loss (19.6%), fatigue (18.6%), decreased appetite (18.6%), anemia (17.5%), vomiting (16.5%), and peripheral neuropathy (16.5%). The incidence of grade 3/4 TRAEs was 35.1%, with the most common being decreased white blood cell count (18.6%) and neutropenia (18.6%). On March 16, 2024, Mabwell (Shanghai) Bioscience announced at the Society of Gynecologic Oncology (SGO) Annual Meeting through a Focused Plenary Oral Presentation the positive clinical trial results of its Nectin-4 targeted ADC in cervical cancer. As of September 25, 2023, 92.50% (37/40) of the participants experienced treatment-related adverse events, with the most common grade 3 treatment-related adverse events being neutropenia at 40.00% (16/40), rash at 17.50% (7/40) and increased gamma-glutamyl transferase at 12.50% (5/40). There were no treatment-related deaths reported. Mabwell's ADC Pipeline Mabwell (Shanghai) Bioscience has developed two antibody-drug conjugates (ADCs), B7H3 ADC 7MW3711 and TROP2 ADC 9MW2921, based on its next-generation conjugation technology platform IDDC™. Both ADCs are currently in Phase I clinical trials. IDDC™ is a next-generation site-specific conjugation technology platform autonomously developed by Mabwell Bioscience, comprising of several systematic core patented technologies: the site-specific conjugation process DARfinity™, the site-specific linker IDconnect™, the novel payload molecule Mtoxin™, and the conditional release structure LysOnly™. The next-generation ADCs developed using these systematic patented technologies exhibit improved structural uniformity, quality stability, efficacy, and tolerance. The LysOnly™ technology enhances the tumor-specific release capacity of ADC drugs, reducing off-target effects. How to search for and analyze the development progress of ADC pharmaceuticals?If you want to learn about the latest developments in ADC drugs, you can use the drug search module of the Synapse database. This module supports searching for ADC drugs by classification through Targeting Moiety, Linker, and Payload. On the search results page, you can easily review information related to the ADC's technical category of the drugs. After clicking to enter the drug details page, you can also effortlessly obtain structural information about the ADC drug. Click on the image below to embark on a brand new journey of drug discovery!