Investigation of Mergo? mechanism of action by quantitative serum protein profiling.

总部位于伦敦的生物技术中小企业Six X Bioscience正在开发基于RNA的递送系统Mergo？，旨在将寡核苷酸治疗药物运送到肝外组织。墨戈号？技术允许开发一个平台，该平台可以被快速设计来探索和筛选巨大而多样的化学空间。事实上，Mergos可以很容易地进行化学修饰，以改变其物理化学性质。6倍的研究表明，化学成分改变的Mergos可以分布到体内的肝外组织(小鼠模型)。更有趣的是，特定的Mergo？候选人表现出细胞嗜性，为细胞特异性药物输送开辟了道路。然而，Mergo的机制是什么？分配到某些单元的问题尚未明确解决。目前关于改变分布的主要假说是基于蛋白质指纹图谱。我们假设改变Mergo？导致生物特性(蛋白质结合剂)的改变，导致分布、细胞摄取和治疗效果的差异。事实上，当注射到生物体液(例如血清或脑脊液)中时，蛋白质被显示与Mergo？结合，形成蛋白质日冕。再说了，莫戈？不同的体内分布曲线已被定性地显示为不同的蛋白质结合(PB)曲线。例如，对血清的整体亲和力发生了变化，形成了更高级别的结构(蛋白质-Mergo？复合体)具有不同的形状和大小。而通过SDS-PAGE分析的下拉实验表明Mergo？对于候选人，他们的身份尚未得到澄清。解析PB指纹将有助于六倍，更全球化的RNAi药物输送领域，将化学身份和生物结果联系起来。更具体地说，细胞外蛋白结合剂可用于了解体内分布，而细胞内PB可能提供毒性和治疗活性的信息。此外，了解蛋白质结合是否从一个物种到另一个物种是保守的，将有助于理解在小动物(小鼠)中观察到的结果是否可以转化为更大的物种(NHP，人类)，从而加速临床前阶段和平台的开发。最后，开发一种稳健的、潜在的高通量鉴定蛋白质结合蛋白的方法可能有助于合理设计Mergo？候选者，并被整合到六重AI/ML化学设计循环中。目前，Mergo增加了哪些选择的修改？候选者是基于小分子的自适应特性。我们相信PB可以用来更好地预测体内行为。综上所述，蛋白质结合鉴定可用于了解作用机制(MOA)、毒性、跨物种差异，并更好地为下一代Mergo？的设计提供信息。候选人。

Sixfold Bioscience, a London-based biotech SME, are developing Mergo?, RNA-based delivery systems designed to carry oligonucleotides therapeutics to extrahepatic tissues. The Mergo? technology allows the development of a platform that can rapidly be engineered to explore and screen a large and diverse chemical space. Indeed, Mergos can be easily chemically modified to change their physicochemical properties. Sixfold has shown that Mergos with altered chemical composition can distribute to extrahepatic tissues _in vivo_ (mice models). More interestingly, certain Mergo? candidates display cell tropism, opening the way to cell-specific drug delivery. Yet, the mechanism by which Mergo? distribute to certain cells specifically has not been addressed. The current leading hypothesis for altered distribution is based on protein fingerprinting.We postulate that modifying the chemical identities of Mergo? results in altered biological identity (protein binders), leading to differences in distribution, cellular uptake and therapeutic effect. Indeed, upon injection to biological fluids (_e.g_ serum or cerebral spinal fluid), proteins are shown to bind Mergo?, forming a protein corona. Moreover, Mergo? with different _in vivo_ distribution profiles have been qualitatively shown to display different protein binding (PB) profiles. For example, whole affinity to serum changed, and the higher-order structures formed (protein-Mergo? complexes) have different shapes and sizes.While pulldown experiments analyzed by SDS-PAGE have revealed that protein binders differ between Mergo? candidates, their identities have not been yet elucidated. Resolving PB fingerprints would help Sixfold, and more globally the RNAi drug delivery field, to link chemical identity and biological outcomes. More specifically, the extracellular protein binders can be used to understand _in vivo_ distribution, while intracellular PB might inform on toxicity and therapeutic activity. Additionally, understanding whether protein binders are conserved from one species to another would help understanding whether results observed in small animals (mouse) can be translated to bigger species (NHP, human), accelerating preclinical phase and platform development. Finally, the development of a robust, potentially high-throughput method to identify protein binders could help to rationally design Mergo? candidates, and be integrated within the Sixfold AI/ML chemical design loop. Currently, the choice of the modifications added to Mergo? candidates is based on ADMET properties of small molecules. We believe that PB can be used to better predict _in vivo_ behaviour. In summary, protein binders identification could be used to understand mechanism of action (MOA), toxicity, cross-species differences and inform better the design of next-generation Mergo? candidates.