BCL6

近年来，靶向蛋白降解（Targeted Protein Degradation, TPD）作为一种新兴的治疗策略，在癌症治疗领域展现出巨大潜力。TPD的核心理念是通过重新编程细胞内的蛋白质降解机制，实现对特定致病蛋白的精准降解。它与传统的抑制剂类药物不同，并非直接阻断蛋白质的功能，而是借助细胞自身的降解系统——泛素 - 蛋白酶体系统（Ubiquitin–Proteasome System, UPS），清除目标蛋白质。这一创新性的策略不仅能够提高药物的选择性和疗效，还有望克服传统治疗手段的诸多局限。泛素-蛋白酶体系统（UPS）UPS是细胞内主要的蛋白质降解系统，负责80-90%的细胞内蛋白质的降解。它通过泛素分子标记需要降解的蛋白质，随后将其送入蛋白酶体进行分解。这一过程高度复杂且精细调控。E3泛素连接酶在其中扮演着关键角色，它能够特异性识别目标蛋白，并将其与泛素分子连接起来。如图1所示：首先，泛素分子通过E1激活酶被激活，随后转移到E2结合酶上，最终在E3连接酶的介导下，泛素分子被连接到目标蛋白上。被泛素标记的蛋白质随后被送入26S蛋白酶体，进行降解。这一系统不仅负责清除受损、错误折叠的蛋白质，还在细胞周期调控、信号传导等生命活动中发挥着关键作用。例如，在缺氧条件下，缺氧诱导因子-1α（HIF-1α）能够逃避免泛素化降解，从而启动一系列适应缺氧的生理反应。这种对蛋白质降解的精确调控，为TPD技术提供了理论基础。图1.泛素-蛋白酶体系统的机制PROTACs和分子胶降解剂目前，TPD领域主要分为两大类技术：异双功能蛋白降解靶向嵌合体（PROTACs）和分子胶降解剂（Molecular Glue Degraders, MGDs）。这两类技术虽然在化学结构和作用机制上有所不同，但都旨在通过促进目标蛋白与E3连接酶之间的相互作用，诱导目标蛋白的泛素化和降解。PROTACs：PROTACs是由两个独立的配体通过化学链连接而成的异双功能分子。其中一个配体能够结合目标蛋白，另一个配体则能够结合E3连接酶。当PROTACs与目标蛋白和E3连接酶同时结合时，会形成一个三元复合物，使目标蛋白靠近E3连接酶，从而促进泛素转移和蛋白质降解。图2清晰地展示了PROTACs的作用机制。以dBET6为例，它能够将BET蛋白（BRD2–BRD4）与CUL4–DDB1–CRBN E3连接酶复合体连接起来，从而实现对BET蛋白的降解。目前，已有多种PROTACs进入临床试验，如针对雄激素受体（AR）的ARV-110和ARV-766，以及针对雌激素受体（ER）的AC682和ARV-471等，这些药物在前列腺癌和乳腺癌的治疗中展现出良好的应用前景。图2.PROTACs的作用机制分子胶降解剂：与PROTACs不同，分子胶降解剂通常不直接与目标蛋白或E3连接酶单独结合，而是通过增强目标蛋白与E3连接酶之间的现有表面互补性，促进它们之间的相互作用。例如，免疫调节亚胺药物（IMiDs）如沙利度胺、来那度胺和泊马度胺就是典型的分子胶降解剂。它们能够增强CRBN（Cereblon）E3连接酶与一系列目标蛋白（如IKZF1和IKZF3）之间的相互作用，导致目标蛋白的降解。图3展示了分子胶降解剂的作用方式。以pomalidomide为例，它通过增强CRBN与目标蛋白之间的亲和力，促进目标蛋白的泛素化和降解。目前，来那度胺和泊马度胺等分子胶降解剂已在多发性骨髓瘤的治疗中获得广泛应用，并取得了显著的临床效果。图3.分子胶降解剂的作用机制新兴的降解模式除了PROTACs和分子胶降解剂，科学家们还不断探索新的降解策略，以进一步拓展TPD技术的应用范围。以下是一些新兴的降解模式：间接降解剂：巧妙的 “间接引导者”间接降解剂通过将目标蛋白的相互作用蛋白招募到E3连接酶，从而间接实现目标蛋白的降解。例如，CR8能够将CDK12招募到DDB1适配器上，CDK12进而招募细胞周期蛋白K到DCAF底物受体通常占据的位置，诱导细胞周期蛋白K 的泛素化（图4）。图4.间接降解剂的作用机制分子内二价胶：创新的“分子内桥梁”分子内二价胶（Intramolecular Bivalent Glues, IBGs）通过同时结合目标蛋白的两个结构域，将其排列成能够增强与E3连接酶相互作用的构象，从而实现目标蛋白的降解。例如，IBG1能够同时结合BRD4的两个溴结构域BD1和BD2，并将其排列成与DCAF16 E3连接酶高亲和力结合的构象（图5）。这一创新的降解模式为设计新型TPD分子提供了新的思路。图5.分子内二价胶的作用机制降解尾：巧妙的“化学修饰”降解尾是指通过在目标蛋白结合剂上添加简单的化学基团，将其转化为高效的降解剂。例如，GNE-0011通过在其表面暴露区域添加一个轻度亲电的丙炔胺尾，实现了对BRD2和BRD4的降解（图6）。这种策略为快速筛选和优化降解剂提供了便利。图6.引入降解尾的作用机制核激素受体降解剂：精准的“受体调控”核激素受体降解剂通过与核激素受体结合，诱导受体的构象变化，从而触发其泛素化和降解。例如，选择性雌激素受体降解（SERDs）如fulvestrant和elacestrant能够通过置换雌激素受（ER）配体结合和激活功能2（AF2）结构域中的螺旋12，触发ER通过RNF111介导的途径降解（图7）。这些降解剂在乳腺癌的治疗中展现出良好的应用前景。图7.核激素受体降解剂的作用机制SUMO依赖性降解：独特的“修饰触发”SUMO依赖性降解通过诱导目标蛋白的SUMO修饰，使其被SUMO靶向E3连接酶（STUbLs）识别并泛素化降解。例如，WRN抑制剂HRO671能够诱导WRN蛋白发生180°的构象变化，被SUMO E3连接酶PIAS4识别并泛素化，随后通过蛋白酶体降解（图8）。这一降解模式为研究蛋白质修饰与降解的关系提供了新的视角。图8.SUMO依赖性降解的作用机制抑制剂诱导的蛋白不稳定化：巧妙的 “功能干扰”一些原本设计为抑制剂的小分子化合物，通过诱导目标蛋白的不稳定化，促使其降解。例如，BI-3802能够诱导BCL6聚合形成丝状结构，增强其与E3连接酶 SIAH1的相互作用，从而实现BCL6的降解（图9）。这种现象为发现新型降解剂提供了意外的线索。图9.抑制剂诱导的蛋白不稳定化的作用机制临床应用：与传统的抑制剂类药物相比，TPD药物具有以下显著优势：（一）更高的选择性和效力：通过诱导目标蛋白与E3连接酶之间的特异性相互作用TPD药物能够实现对目标蛋白的精准降解，减少对非目标蛋白的影响。例如SD-36能够选择性降解STAT3，尽管其亲本抑制剂SI-109对STAT1和STAT4也具有一定的亲和力。（二）低剂量和持续效果：TPD药物通过催化机制发挥作用，能够在亚化学计量的情况下诱导目标蛋白的降解，从而在较低剂量下实现持久的治疗效果。例如，ACBI3 能够在降解13种常见的KRAS突变体时，展现出比其亲本抑制剂更强的效力和更持久的MAPK信号抑制作用。（三）克服传统治疗的耐药性：TPD药物能够同时破坏目标蛋白的多种功能，包括其获得的新功能（如BTK的新异性支架功能），从而克服传统治疗的耐药性。例如，PROTACs如NX-2127和NX-5948能够降解BTK，有效杀死对抑制剂耐药的细胞。临床试验中的 TPD 药物：目前，多项 TPD 药物的临床试验正在如火如荼地进行中(见下表)。目前TPD技术面临的挑战：（一）药物设计的复杂性TPD药物的设计需要综合考虑目标蛋白与E3连接酶之间的相互作用、药物的化学稳定性和生物利用度等多个因素。例如，PROTACs的设计通常需要在目标蛋白和E3连接酶之间找到合适的化学连接链，以确保三元复合物的稳定性和降解效率。此外，药物的理化性质（如分子量、溶解性、渗透性等）也会影响其药代动力学和药效学特性。（二）耐药性的产生与传统药物类似，TPD药物也可能面临耐药性问题。例如，CRBN基因的突变可能导致来那度胺等分子胶降解剂的耐药性。此外，E3连接酶复合物的其他亚基发生突变或表达量变化，也可能影响TPD药物的疗效。（三）药物的药代动力学和药效学特性TPD药物的药代动力学和药效学特性（如吸收、分布、代谢、排泄等）对其临床应用具有重要影响。例如，PROTACs由于其较大的分子量和复杂的化学结构，往往具有较差的口服生物利用度和血脑屏障穿透能力。这些特性可能限制药物在体内的分布和作用时间，影响其治疗效果。（四）安全性和毒性问题TPD药物的安全性和毒性也是需要重点关注的问题。由于TPD药物通过诱导目标蛋白的降解发挥作用，其潜在的非目标效应（如对其他蛋白质的非特异性降解）可能导致不良反应。此外，药物对E3连接酶的过度激活或抑制也可能干扰细胞内的正常蛋白质稳态，引发毒性反应。结论靶向蛋白降解技术作为癌症治疗领域的一项重大突破，为患者带来了新的希望和选择。从PROTACs和分子胶降解剂的经典模式，到新兴的降解策略，TPD技术不断拓展着我们的视野和可能性。尽管其在发展过程中面临诸多挑战，但通过科学家们的不懈努力和创新，我们有理由相信，TPD技术将在未来的癌症治疗中扮演越来越重要的角色，开启癌症治疗的新篇章。原文链接：https://doi.org/10.1038/s41568-025-00817-8声明：发表/转载本文仅仅是出于传播信息的需要，并不意味着代表本公众号观点或证实其内容的真实性。据此内容作出的任何判断，后果自负。若有侵权，告知必删！长按关注本公众号   粉丝群/投稿/授权/广告等请联系公众号助手 觉得本文好看，请点这里↓

– ARV-393 demonstrated strong synergistic antitumor activity, including complete regressions, in combination with standard-of-care chemotherapy, biologics, and select investigational oral small molecule inhibitors – – Findings support continued evaluation of ARV-393 combinations in non-Hodgkin lymphoma – NEW HAVEN, Conn., April 28, 2025 (GLOBE NEWSWIRE) -- Arvinas, Inc. (Nasdaq: ARVN), a clinical-stage biotechnology company working to develop a new class of drugs based on targeted protein degradation, today presented data from preclinical combination studies of ARV-393, the company’s investigational PROteolysis TArgeting Chimera (PROTAC) B-cell lymphoma 6 protein (BCL6) degrader. BCL6 is a transcriptional repressor protein and a known driver of B-cell lymphomas. Data demonstrated synergistic antitumor activity, including complete regressions, in combination with standard of care (SOC) chemotherapy, SOC biologics, and investigational oral small molecule inhibitors (SMIs) in high grade B-cell lymphoma (HGBCL) and aggressive diffuse large B-cell lymphoma (DLBCL) models. The results from these preclinical studies were shared in a poster presentation at the 2025 American Association for Cancer Research (AACR) annual meeting in Chicago, Illinois. Key findings from the studies included: ARV-393 in combination with SOC chemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone [R-CHOP]), induced significantly greater tumor growth inhibition compared with rituximab, CHOP, R-CHOP, or ARV-393 alone, with complete tumor regressions in all mice treated with the ARV-393 and R-CHOP combination.ARV-393 in combination with SOC biologics targeting CD20 (rituximab), CD19 (tafasitamab), or CD79b (polatuzumab vedotin) resulted in tumor regressions and demonstrated significantly stronger tumor growth inhibition compared with each agent alone.In preclinical models, ARV-393 increased CD20 expression, providing additional support for the exploration of combinations with CD20-targeted agents and in the context of low or loss of CD20 expression.ARV-393 in combination with investigational small molecule inhibitors targeting clinically validated oncogenic drivers of lymphoma, such as BTK (acalabrutinib), BCL2 (venetoclax), or EZH2 (tazemetostat), resulted in superior tumor growth inhibition compared with each agent alone, with tumor regressions in all mice treated with the combinations. “Given that combination regimens are the foundation of lymphoma treatment, we are encouraged by the strength of these preclinical combination data, which demonstrate complete tumor regressions in aggressive lymphoma models,” said Noah Berkowitz, M.D., Ph.D., Chief Medical Officer at Arvinas. “We believe these preclinical data demonstrate potential for broad combinability of ARV-393 and provide a compelling rationale for considering combination strategies as we work to bring forward new therapeutic options for lymphoma patients.” A Phase 1 study of ARV-393 is enrolling patients with relapsed/refractory non-Hodgkin lymphoma, including DLBCL (NCT06393738). Additional detail on the ARV-393 data presentation at AACR 2025: Poster Title: ARV-393, a PROteolysis TArgeting Chimera (PROTAC) BCL6 Degrader, Combined With Biologics or Small-Molecule Inhibitors Induces Tumor Regressions in Diffuse Large B-Cell Lymphoma ModelsAbstract: 1655Session Title: Degraders and Glues 2 Session Type: Experimental and Molecular TherapeuticLocation: Poster Section 18Poster Board Number: 15Date: Monday, April 28, 2025Lecture Time: 9:00 a.m. – 12:00 p.m. CT About ARV-393ARV-393 is an investigational, orally bioavailable PROteolysis TArgeting Chimera (PROTAC) designed to degrade B-cell lymphoma 6 protein (BCL6), a transcriptional repressor and major driver of B-cell lymphomas. During B-cell development, tightly controlled BCL6 protein expression regulates >600 genes to facilitate rapid B-cell proliferation and tolerance of somatic hypermutation and gene recombination for antibody generation. Deregulated BCL6 expression is common in B-cell lymphoma and promotes cancer cell survival, proliferation, and genomic instability. PROTAC-mediated degradation has the potential to address the historically undruggable nature of BCL6. ARV-393 is currently in a Phase 1 clinical trial in patients with relapsed/refractory non-Hodgkin lymphoma. About ArvinasArvinas (Nasdaq: ARVN) is a clinical-stage biotechnology company dedicated to improving the lives of patients suffering from debilitating and life-threatening diseases. Through its PROteolysis TArgeting Chimera (PROTAC) protein degrader platform, the Company is pioneering the development of protein degradation therapies designed to harness the body’s natural protein disposal system to selectively and efficiently degrade and remove disease-causing proteins. Arvinas is currently progressing multiple investigational drugs through clinical development programs, including vepdegestrant, targeting the estrogen receptor for patients with locally advanced or metastatic ER+/HER2- breast cancer; ARV-393, targeting BCL6 for relapsed/refractory non-Hodgkin Lymphoma; and ARV-102, targeting LRRK2 for neurodegenerative disorders. Arvinas is headquartered in New Haven, Connecticut. For more information about Arvinas, visit www.arvinas.com and connect on LinkedIn and X. Forward-Looking StatementsThis press release contains forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995 that involve substantial risks and uncertainties, including statements regarding the potential for Arvinas’ investigational oral PROteolysis TArgeting Chimera (PROTAC) degrader ARV-393 to treat relapsed/refractory non-Hodgkin lymphoma; the preclinical data for ARV-393 demonstrating the potential for broad combinability and supporting continued evaluation of ARV-393 combinations in non-Hodgkin lymphoma associated with B-cell lymphoma 6 protein (“BCL6”) dysfunction; and PROTAC-mediated degradation having the potential to address the historically undruggable nature of BCL6.. All statements, other than statements of historical facts, contained in this press release, including statements regarding Arvinas’ strategy, future operations, future financial position, future revenues, projected costs, prospects, plans and objectives of management, are forward-looking statements. The words “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “predict,” “project,” “target,” “potential,” “will,” “would,” “could,” “should,” “continue,” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Arvinas may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements, and you should not place undue reliance on such forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements Arvinas makes as a result of various risks and uncertainties, including but not limited to: whether Arvinas will be able to successfully conduct and complete development for its product candidates, including ARV-393, including whether Arvinas initiates and completes clinical trials for its product candidates and receives results from its clinical trials on its expected timelines or at all; Arvinas’ ability to protect its intellectual property portfolio; whether Arvinas’ cash and cash equivalent resources will be sufficient to fund its foreseeable and unforeseeable operating expenses and capital expenditure requirements; and other important factors discussed in the “Risk Factors” section of Arvinas’ Annual Report on Form 10-K for the year ended December 31, 2024 and subsequent other reports on file with the U.S. Securities and Exchange Commission. The forward-looking statements contained in this press release reflect Arvinas’ current views with respect to future events, and Arvinas assumes no obligation to update any forward-looking statements, except as required by applicable law. These forward-looking statements should not be relied upon as representing Arvinas’ views as of any date subsequent to the date of this release. Contacts:Investors:Jeff Boyle+1 (347) 247-5089Jeff.Boyle@arvinas.com Media:Kirsten Owens+1 (203) 584-0307Kirsten.Owens@arvinas.com

– Oral presentation will serve as first presentation of detailed results from the Phase 3 VERITAC-2 clinical trial – April 23, 2025 -- Arvinas, Inc. (Nasdaq: ARVN) today announced that data from the global Phase 3 VERITAC-2 clinical trial (NCT05654623) evaluating vepdegestrant versus fulvestrant in patients with estrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+/HER2-) advanced or metastatic breast cancer will be presented as a late-breaking oral presentation at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting, taking place May 30 – June 3 in Chicago, IL. The presentation includes the first pivotal data for vepdegestrant, a potential first-in-class investigational oral PROteolysis TArgeting Chimera (PROTAC) estrogen receptor (ER) degrader. Vepdegestrant is being jointly developed by Arvinas and Pfizer for the treatment of patients with advanced or metastatic ER+/HER2- breast cancer. Presentation details are as follows: Title: Vepdegestrant, a PROTAC estrogen receptor (ER) degrader, vs. fulvestrant in ER-positive/human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer (aBC): results of the global, randomized, phase 3 VERITAC-2 study Presenting Author: Erika P. Hamilton, MD, Breast Cancer Research Program, Sarah Cannon Research Institute Abstract Number: LBA1000 Session Date, Time and Location: Saturday, May 31, 2025, 1:15 PM-4:15 PM CT in Hall B1 Session Type and Title: Oral Abstract Session – Breast Cancer—Metastatic Vepdegestrant is an investigational, orally bioavailable PROTAC (PROteolysis TArgeting Chimera) protein degrader designed to specifically target and degrade the estrogen receptor (ER) for the treatment of patients with ER-positive (ER+)/human epidermal growth factor receptor 2 (HER2)-negative (ER+/HER2-) breast cancer. Vepdegestrant is being developed as a potential monotherapy and as part of combination therapy across multiple treatment settings for ER+/HER2- metastatic breast cancer. In July 2021, Arvinas announced a global collaboration with Pfizer for the co-development and co-commercialization of vepdegestrant; Arvinas and Pfizer will share worldwide development costs, commercialization expenses, and profits. The U.S. Food and Drug Administration (FDA) has granted vepdegestrant Fast Track designation as a monotherapy in the treatment of adults with ER+/HER2- advanced or metastatic breast cancer previously treated with endocrine-based therapy. Arvinas (Nasdaq: ARVN) is a clinical-stage biotechnology company dedicated to improving the lives of patients suffering from debilitating and life-threatening diseases. Through its PROTAC (PROteolysis TArgeting Chimera) protein degrader platform, the Company is pioneering the development of protein degradation therapies designed to harness the body’s natural protein disposal system to selectively and efficiently degrade and remove disease-causing proteins. Arvinas is currently progressing multiple investigational drugs through clinical development programs, including vepdegestrant, targeting the estrogen receptor for patients with locally advanced or metastatic ER+/HER2- breast cancer; ARV-393, targeting BCL6 for relapsed/refractory non-Hodgkin Lymphoma; and ARV-102, targeting LRRK2 for neurodegenerative disorders. Arvinas is headquartered in New Haven, Connecticut. The content above comes from the network. if any infringement, please contact us to modify.