Maximising Efficiency of Liquid Phase Oligo Synthesis (MELOS)

寡核苷酸（oligo）是通常含有15-25个核苷酸/核苷酸类似物的核苷酸单体的序列，它们为广泛的医学病症提供有希望的治疗。目前有15种寡核苷酸药物已在EMA和FDA之间获得批准。近年来，越来越多的寡核苷酸在临床试验中显示出对大患者群体疾病的良好效果。例如，Inclisiran是一种用于治疗心血管疾病（数千名患者）的寡核苷酸，于2020年在欧洲获得批准，并于2021年开始在NHS上市。据估计，Inclisiran将在未来三年内在英国治疗30万名患者。虽然固相合成（SPS）是生产寡核苷酸的主要生产工艺，但它存在一些局限性。主要挑战包括：** 缺乏可扩展性 **（最大约10- 20 kg批量），** 高成本 **（800- 1000英镑/g寡聚物）和与该方法相关的 ** 沉重的环境负担 **（约4300 kg/kg PMI）。这就迫切需要可持续的、吨/年规模的寡核苷酸生产路线，以使寡核苷酸能够在大规模人群中为患者带来益处。Grand Challenge 'GC 3'财团（包括诺华、阿斯利康、Alnylam、Exactmer、CPI）正在开发Nanostar Sieving，这是一种基于液相合成 **（LPS）的突破性新技术，用于生产寡核苷酸。对于寡核苷酸生产，该平台定位为在GMP条件下（100 kg/批次）易于放大，具有高粗纯度寡核苷酸（70-90%）和使用类似的亚磷酰胺单体当量（1.5当量/循环）。最大限度地提高液相低聚物合成的效率（MELOS）是Exactmer，伦敦玛丽皇后大学（QMUL），CPI和阿斯利康之间的英国合作，旨在建立在GC 3的成功基础上。这个为期24个月的项目将专注于 ** Nanostar Sieving平台 ** 的工艺效率和可持续性的阶跃变化，用于大规模合成寡核苷酸。通过使用具有更好的膜选择性和更高溶解度的Nanostar集线器和单体，将进一步开发当前的化学。进一步的步骤变化包括在Nanostar筛分工艺中集成溶剂循环回路，与SPS技术相比，总工艺质量强度 **（PMI）降低40%。溶剂干燥装置将允许过程中的水去除，这将减少所需的亚磷酰胺当量至接近化学计量（即，<1.1当量）。将实施在线实时分析，以监测回收溶剂的质量。此外，这项工作还需要确保 ** 以最小的环境影响获得最高质量的产品，并降低成本 **。

Oligonucleotides (oligos) are sequences of nucleotides monomers which usually contain between 15-25 nucleotides/ nucleotide-analogues, they offer promising treatment for a wide range of medical conditions. There are now 15 oligo drugs which have been approved between the EMA and FDA. In recent years, an **increasing number of oligos in clinical trials** have shown excellent results for diseases with large patient populations. For example, Inclisiran, an oligo developed for the treatment of cardiovascular disease (thousands of patients), was approved in Europe in 2020 and is available on the NHS since 2021\. It is estimated Inclisiran will treat 300,000 patients in the UK in the next three years.While Solid Phase Synthesis (SPS) is the dominant manufacturing process to produce oligos it presents several limitations. The main challenges comprise: **the lack of scalability** (~10-20kg batch sizes maximum), the **high costs** (£800-£1000/g of oligos) and the **heavy environmental burden** associated with the process (~4300kg/kg PMI). This creates a critical need for sustainable, ton-per-annum-scale oligo production routes to enable oligos to deliver patient benefits in large populations.The Grand Challenge 'GC3' consortium (comprising Novartis, AstraZeneca, Alnylam, Exactmer, CPI) is developing Nanostar Sieving, a **breakthrough new technology based on Liquid Phase Synthesis** (LPS) to manufacture oligos. For oligo manufacture, this platform is positioned to provide ease of scaling under GMP conditions (100kg/batch), with high crude purity oligos (70-90%) and use of similar phosphoramidite monomer equivalents (1.5 equivalents/cycle). Maximising Efficiency of Liquid-phase Oligo Synthesis (MELOS) is a UK based collaboration between Exactmer, Queen Mary University of London (QMUL), CPI and AstraZeneca, seeking to build on the success of GC3\. This 24-month project will focus on **a step change in the process efficiency and sustainability of the Nanostar Sieving platform** for the synthesis of oligos on large scale. The current chemistry will be further developed by using Nanostar hubs and monomers with better membrane selectivities and higher solubilities. Further step changes include integration of a solvent recycling loop within the Nanostar Sieving process, seeking a **reduction of 40% in the total Process Mass Intensity** (PMI) compared to SPS technology. A solvent drying device will allow in-process water removal that will reduce required phosphoramidites equivalents to close to stoichiometric (i.e., <1.1 equivalents). In-line, real-time analysis will be implemented to monitor the quality of the recycled solvent. Furthermore, this work is required to ensure the **highest quality of product is obtained with minimal environmental impact, and at reduced costs**.