MTM1

*仅供医学专业人士阅读参考 近年来，抗氧化领域最重磅的炸弹是：大量研究表明，抗氧化促癌。 早在2011年，一项发表在JAMA上的临床研究显示，通过膳食补充维生素E的健康男性，患前列腺癌的风险显著增加17%[1]。 2019年，瑞典卡罗林斯卡医学院的研究人员在《细胞》上发表一篇重磅研究论文，发现长期补充维生素E等抗氧化剂会促进KRAS驱动的肺癌转移[2]。 仅半年之后，美国Roswell Park癌症研究中心发表在JCO上的一项临床研究表明，在化疗前或期间服用抗氧化剂与癌症复发风险增加41%有关[3]。 就在去年，瑞典卡罗林斯卡医学院的研究人员又发现，维生素C等抗氧化剂还可以促进肿瘤里面长血管，进而促进肿瘤的进展[4]。 看完上述研究成果，我猜你很自然就想到了一个问题：既然抗氧化剂会促癌，那促氧化剂能不能抗癌呢？ 还真能！ 今天，由美国冷泉港实验室Lloyd C. Trotman领衔的研究团队，在《科学》杂志发表了一篇重要研究成果[5]。 他们基于独创的前列腺癌小鼠模型，发现在小鼠的饮用水中添加促氧化剂、水溶性维生素K前体——亚硫酸氢钠甲萘醌（MSB），可以持久地抑制前列腺癌的进展。他们还发现，MSB是通过一种独特的氧化性细胞死亡机制杀死癌细胞。 值得一提的是，除了可以抗癌之外，Trotman团队还发现，MSB还可以通过类似的机制，将致死性X连锁肌管肌病小鼠模型的生存时间延长1倍。 ▲ 论文首页截图 作为一名研究前列腺癌的专家，Lloyd C. Trotman对2011年发表的SELECT研究数据印象深刻。 要知道，SELECT研究本身是想探索补充硒或维生素E在健康男性中预防前列腺癌的效果，结果二者不仅不具有防癌的效果[6]，反而增加了受试者患前列腺癌的风险[1]。 这一发现让人大跌眼镜。 在随后的几年里，陆续有多个研究发现了抗氧化剂的促癌作用。这让Trotman团队不得不思考一个问题：促氧化剂有可能具备抗癌的功能吗？这个问题并没有确切的答案。 在上述背景之下，Trotman团队基于实验室自主研发的、可荧光成像的转移性前列腺癌小鼠模型RapidCaP，探索了促氧化剂是否存在抗癌作用。这个研究使用的促氧化剂主要为维生素K前体——甲萘醌（又称维生素K3），而且以水溶性亚硫酸氢钠甲萘醌（MSB）的形式给药（浓度为150μg/ml）。 在连续18周的成像研究过程中，研究人员发现，与饮水的对照组小鼠相比，饮用水添加MSB的小鼠表现出显著且持久的治疗反应。值得一提的是，MSB治疗效果的持久性甚至超过了去势疗法。 ▲ MSB的治疗效果 那么，那些对MSB敏感的癌细胞，究竟是如何被MSB杀死的呢？ Trotman团队将MSB杀死的癌细胞，与细胞凋亡、程序性坏死和铁死亡的细胞做了比较。他们发现，三种常见死亡方式的阻断药物，不能抑制MSB对细胞的杀伤作用。这说明，MSB杀死的癌细胞的方式，与上述三者不同。 在后续的研究中，他们证实MSB诱发的是一种独特的氧化性细胞死亡机制。 ▲ MSB治疗后，癌细胞的死相 为了揭示这种独特的死亡机制，Trotman团队开始在全基因组层面筛选调节因子。 从筛查的总体来看，内吞作用与MSB诱导的细胞死亡密切相关。随后基因层面的分析发现，MSB会氧化磷脂酰肌醇3-激酶（PI3K）VPS34的关键半胱氨酸，导致VPS34失活。而VPS34是内体上调节内吞（囊泡和膜的转运）和自噬的核心成分。一旦VPS34失活，初级内体的形成就会出现异常，进而导致细胞死亡。 Trotman团队将MSB诱导的这种独特死亡方式命名为“triaptosis”。 ▲ 机制示意图[7] 上述机制让Trotman团队想到了另一种疾病——X连锁肌管肌病（XLMTM）。 这是一种罕见的、MTM1基因突变引起的、会危及生命的先天性肌肉疾病。由于MTM1磷酸酶是VPS34的拮抗剂，因此MTM1的缺失，会增强VPS34的功能。 因此，Trotman想知道，能抑制VPS34活性的MSB，是否能治疗X连锁肌管肌病。 他们先构建了X连锁肌管肌病小鼠模型，发现这些小鼠存活时间中位数是1个月，这与之前报道的类似。让他们欣喜的是，那些在饮用水中加入MSB（150μg/ml）的X连锁肌管肌病小鼠模型，中位存活时间是62天。 而且，MSB治疗组的体重有所增加，肌肉组织学和肌纤维超微结构也得到了改善。 ▲ MSB治疗X连锁肌管肌病小鼠模型的效果 总的来说，Trotman团队的这项研究成果表明，促氧化剂甲萘醌（维生素K3）可以通过抑制激酶VPS34的活性，破坏癌细胞的内吞，导致癌细胞发生独特的“triaptosis”死亡。这不仅意味着促氧化剂具有抗癌能力，而且还指出了一个治疗癌症的新方向，靶向“氧化还原检查点”。 此外，研究揭示的机制，还意外地为罕见病X连锁肌管肌病找到了一种潜在的疗法，未来也值得开展进一步探索。 最后，需要提醒大家的是，这项基础研究还不足以支持在临床上使用MSB治疗前列腺癌，未来还需要临床研究检验MSB的疗效。此外，长期补充促氧化剂可能会产生有害后果[8]。 参考文献： [1].Klein EA, Thompson IM Jr, Tangen CM, et al. Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2011;306(14):1549-1556. doi:10.1001/jama.2011.1437 [2].Wiel C, Le Gal K, Ibrahim MX, et al. BACH1 Stabilization by Antioxidants Stimulates Lung Cancer Metastasis. Cell. 2019;178(2):330-345.e22. doi:10.1016/j.cell.2019.06.005 [3].Ambrosone CB, Zirpoli GR, Hutson AD, et al. Dietary Supplement Use During Chemotherapy and Survival Outcomes of Patients With Breast Cancer Enrolled in a Cooperative Group Clinical Trial (SWOG S0221). J Clin Oncol. 2020;38(8):804-814. doi:10.1200/JCO.19.01203 [4].Wang T, Dong Y, Huang Z, et al. Antioxidants stimulate BACH1-dependent tumor angiogenesis. J Clin Invest. 2023;133(20):e169671. Published 2023 Oct 16. doi:10.1172/JCI169671 [5].Swamynathan MM, Kuang S, Watrud KE, et al. Dietary pro-oxidant therapy by a vitamin K precursor targets PI 3-kinase VPS34 function. Science. 2024;386(6720):eadk9167. doi:10.1126/science.adk9167 [6].Lippman SM, Klein EA, Goodman PJ, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2009;301(1):39-51. doi:10.1001/jama.2008.864 [7].Pannia E, Dowling JJ. A pro-oxidant suppresses unrelated diseases. Science. 2024;386(6720):380-381. doi:10.1126/science.adt2538 [8].Shieh PB, Kuntz NL, Dowling JJ, et al. Safety and efficacy of gene replacement therapy for X-linked myotubular myopathy (ASPIRO): a multinational, open-label, dose-escalation trial. Lancet Neurol. 2023;22(12):1125-1139. doi:10.1016/S1474-4422(23)00313-7 本文作者丨BioTalker

The preliminary results are from the ASPIRO open label trial conducted by Astellas Pharma with a gene therapy designed and developed preclinically by Genethon After gene therapy treatment, 16 of the 24 children can breathe without assistance, 20 can sit up, 12 can stand and 8 can walk without support (see video of one patient’s progress - ) The trial has been paused to investigate severe side effects which caused the death of four children PARIS--(BUSINESS WIRE)-- Genethon, a unique non-profit gene therapy R&D organization founded by the French Muscular Dystrophy Association (AFM-Telethon), today announced The Lancet Neurology published online preliminary results of a clinical trial conducted by Astellas Pharma using a gene therapy developed by Genethon for X-linked myotubular myopathy, a rare genetic muscle disease affecting 1 in 50,000 newborn boys. Myotubular myopathy is caused by mutations in the MTM1 gene encoding myotubularin, a protein involved in muscle cell function. Characterized by extreme muscle weakness and severe respiratory distress, 50% of affected children die before age 18 months and 75% die before age 10. The gene therapy uses an adeno-associated viral vector (AAV8) to deliver a copy of the MTM1 gene. Of 24 children enrolled in the ASPIRO trial, conducted in France, Germany, Canada and the U.S., 16 of them can now breathe without assistance, 12 stand up on their own, and 8 can walk. The trial has been paused for an investigation into the origins of the complications responsible for the deaths of 4 children, who showed signs of pre-exiting hepatobiliary pathology. “These clinical results show both how spectacularly effective gene therapy can be, and the challenges that remain, particularly in terms of side effects in certain contexts,” said Frederic Revah, Genethon CEO. “While our teams are already committed to understanding and anticipating these issues, the knowledge gained from this clinical trial, which highlights certain limitations and particular hepatic susceptibilities, is rich in lessons for the entire scientific community.” Ana Buj-Bello, Director of Research at Inserm and head of Genethon’s Neuromuscular Diseases and Gene Therapy team, designed the gene therapy. She is one of the authors on The Lancet Neurology article and co-authored the preclinical work that led to the ASPIRO trial. Dr. Buj-Bello remarked, “I've devoted my entire career working on myotubular myopathy. It took years of research to imagine, design and demonstrate the efficacy of the gene therapy for this very severe and complex disease. Even though we absolutely must understand the reasons for the adverse effects observed in this clinical trial, it is exceptional to see children who were known to be doomed make incredible progress thanks to this drug candidate.” See the video of one patient’s progress in France. This patient was treated at I-Motion, the Institute of Myology’s French pediatric clinical trials center: Genethon entered an agreement with Audentes Therapeutics in 2014 for the preclinical development of the gene therapy. Astellas acquired the gene therapy in 2019 with the company’s acquisition of Audentes. About Genethon As a pioneer in the discovery and development of gene therapies for rare diseases, Généthon is a non-profit laboratory that was established by AFM-Telethon. A first gene therapy for spinal muscular atrophy to which Généthon contributed has obtained a product license. With more than 200 scientists and professional staff, Genethon is pursuing its aim to develop therapies which change the lives of patients suffering from rare genetic diseases. Thirteen products developed by Genethon are in clinical trial for diseases of the liver, blood, immune system, muscles and eyes. Seven other products could enter clinical trials over the next five years. More information at .

Astellas is continuing to investigate how AT132 exacerbates liver conditions. Astellas has shared a detailed look at the four deaths in its AT132 gene therapy clinical trial. Writing in The Lancet Neurology, the drugmaker explained that the liver toxicity seen in the trial differs from cases linked to other therapies—and made the case that the drug can still provide transformative clinical benefits.   The paper presents data collected in the ASPIRO trial through Feb. 28, 2022. By that time, the FDA had put the study of children with X-linked myotubular myopathy (XLMTM), a life-threatening condition that causes muscle weakness and respiratory distress, on clinical hold for a second time in response to a fourth death. The study remains on hold.  Astellas shared details of the events leading up to the four deaths in the paper. All four patients had cholestatic liver failure at the time of death. Five of the 20 surviving dosed participants suffered serious treatment-related hepatobiliary adverse events. Analyses of antibodies, cellular markers and other factors suggest the adverse events weren’t caused by immune responses, although Astellas lacks the data to draw firm conclusions. The four patients who died all received immunosuppressive regimens, but the drugs had no apparent benefits. Liver toxicities caused by other gene therapies have responded to immune-modulating therapies. Assessments of the surviving participants revealed liver laboratory abnormalities before and after dosing with AT132. The abnormalities included features thought to be linked to intrahepatic cholestasis, a liver condition that causes the buildup of bile acids, and may have been implicated in the deaths.  Going into the clinical trial, the potential link between XLMTM and cholestatic liver disease was “largely unrecognized,” according to the researchers. The paper cites multiple case series and reports that have described the link since Astellas and the FDA paused ASPIRO, plus details of Dynacure’s decision to stop a trial of an antisense nucleotide in a related myopathy in response to liver enzyme elevations. Astellas is continuing to investigate how AT132 exacerbates liver conditions. Addressing the safety issues may unleash a therapy that showed some clinical promise in the trial. Astellas linked the therapy to improvements on respiratory parameters, including reductions in ventilator use, that the researchers see as evidence AT132 can provide “transformative clinical improvements.” The investigations may benefit Astellas even if it fails to resurrect AT132. In June, the drugmaker struck a deal for exclusive rights to Kate Therapeutics’ preclinical XLMTM gene therapy KT430, which uses a novel MyoAAV capsid to deliver a functional copy of the MTM1 gene. AT132 uses an AAV8 vector to deliver the gene.