Advancing a novel experimental mRNA-based therapy for Classic Galactosemia

项目摘要/摘要 人类遗传性半乳糖-1-磷酸尿苷转移酶(GalT，E.C.2.7.7.12)活性缺陷可 导致一种称为典型半乳糖症(OMIM 230400)的潜在致命性疾病。尽管有拯救生命的后果， 新生儿筛查、早期诊断和半乳糖限制饮食，许多典型的半乳糖血症患者在晚些时候会遭受 生活中的并发症包括生长、神经心理和语言发育迟缓以及原发性卵巢功能不全 (POI)。目前还没有令人满意的治疗方法来预防/减轻这些并发症。精准的 这些并发症的发病机制尚不清楚，尽管糖蛋白/脂类的异常半乳糖化 慢性暴露于半乳糖代谢受阻的有毒中间体所致的肌醇磷脂信号转导 易感组织中的致病途径已被提出。但无论提议的机制和任何相关的 争议，没有人会争论这种疾病的根本原因是受影响的人体内GALT酶活性不足 纸巾。因此，我们与莫德纳公司的同事合作，探索我们是否可以增强功能性GALT 创新的GalT mRNA疗法在经典半乳糖血症动物模型中的活性。具体来说，我们假设 通过Galt mRNA治疗靶向增强肝脏GALT活性足以恢复全身半乳糖 代谢和改善典型半乳糖血症的疾病相关表型。初步结果显示， GALT-/-小鼠静脉注射人GALT mRNA可诱导肝脏表达活性高、持续时间长的GALT 能迅速有效地降低肝脏和其他一些外周组织中GAL-1P的含量，并显著降低 血浆半乳糖。然而，现在判断生物标记物校正是否能导致实际的表型改善还为时过早。因此， 我们的目标是在这一应用中证明，在小鼠模型中，肝脏GALT活性的单独增强 半乳糖血症足以改善与疾病相关的表型(目标1)，并恢复正常的全身半乳糖 代谢(氧化)(目标2)。如果我们成功，我们将能够将这种实验性的mRNA疗法推进到 临床试验(高额奖励)，这可能带来一种创新的疗法，以解决患者未得到满足的医疗需求- 一个影响很大的结果。此外，有关最佳治疗时机和预测价值的关键信息 拟议工作中将揭示的生物标记物将对疾病过程提供重要的见解，并指导 开发其他方式，包括基因治疗。最后但并非最不重要，如果我们能证明半乳糖的恢复 肝脏中的新陈代谢可以显著改善全身半乳糖的氧化，这可能导致饮食 放松(高影响)和这种治疗策略可以应用于靶向治疗的其他代谢性疾病 是首选的(宽影响)。

PROJECT SUMMARY / ABSTRACT Hereditary deficiency of galactose-1-phosphate uridylyltransferase (GALT, E.C. 2.7.7.12) activity in humans can lead to a potentially lethal disease called Classic Galactosemia (OMIM 230400). Despite the life-saving consequences of newborn screening, early diagnosis, and a galactose-restricted diet, many patients with Classic Galactosemia suffer later in life from complications including growth, neuropsychological, and speech delays as well as primary ovarian insufficiency (POI). There are currently no satisfactory treatments available to prevent/alleviate any of these complications. The precise pathogenic mechanisms of these complications remain unclear, although aberrant galactosylation of glycoproteins/lipids and inositol phospholipid signaling caused by the chronic exposure to toxic intermediates of the blocked galactose metabolic pathway in susceptible tissues have been proposed. But regardless of the proposed mechanisms and any of the associated controversies, no one will debate that the root cause for the disease is the deficiency of GALT enzyme activity in the affected tissues. Therefore, we collaborated with colleagues at Moderna Inc. to explore if we could augment functional GALT activity in an animal model of Classic Galactosemia with an innovative GALT mRNA therapy. Specifically, we hypothesize that targeted augmentation of hepatic GALT activity by GALT mRNA therapy is sufficient to restore whole-body galactose metabolism and ameliorate the disease-relevant phenotypes in Classic Galactosemia. Preliminary results showed that intravenous injection of human GALT mRNA in GalT-/- mice resulted in hepatic expression of active, long-lasting GALT enzyme, which rapidly and effectively reduced gal-1P in liver and some other peripheral tissues and significantly lowered plasma galactose. Yet, it is too early to tell if biomarker correction can lead to actual phenotypic improvements. Therefore, we aim to demonstrate in this application that sole augmentation of hepatic GALT activity in a mouse model of Galactosemia is sufficient to ameliorate the disease-relevant phenotypes (Aim 1) and restore normal whole-body galactose metabolism (oxidation) (Aim 2). If we are successful, we will be able to advance this experimental mRNA therapy to clinical trials (high reward), and this could bring an innovative therapy to address the unmet medical needs of the patients - a high-impact outcome. Moreover, the critical information about the optimal timing of treatment and predictive values of the biomarkers to be revealed in the proposed work will render significant insights to the disease process and guide the development of other modalities, including gene therapy. Last but not least, if we can show that restoration of galactose metabolism in the liver can result in significant improvement of whole-body galactose oxidation, this could lead to diet relaxation (high impact) and such therapeutic strategy could be applied to other metabolic diseases at which targeted therapy is preferred (wide impact).