Maximising Efficiency of Liquid Phase Oligo Synthesis (MELOS)

寡核苷酸（oligos）是核苷酸单体序列，通常包含15-25个核苷酸/核苷酸类似物，它们为广泛的医疗条件提供了有希望的治疗。现在已经有15种寡糖药物获得了EMA和FDA的批准。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优异效果。例如，为治疗心血管疾病（数千名患者）而开发的寡糖Inclisiran于2020年在欧洲获得批准，并自2021年起在NHS上提供。据估计，未来三年，Inclisiran将在英国治疗30万名患者。虽然固相合成（SPS）是生产低聚物的主要制造工艺，但它存在一些局限性。主要挑战包括：**缺乏可扩展性**（最大批量约10-20kg）， **高成本**（800- 1000英镑/g低聚物）和**与该过程相关的沉重环境负担** (~4300kg/kg PMI)。这就产生了对可持续的、每年吨级的低聚物生产路线的迫切需求，以使低聚物能够为大量患者提供益处。GC3联盟（由诺华、阿斯利康、Alnylam、Exactmer、CPI组成）正在开发Nanostar筛分技术，这是一项基于液相合成（LPS）制造低聚物的突破性新技术。对于低聚物的生产，该平台的定位是在GMP条件下（100kg/批）易于缩放，具有高粗纯度低聚物（70-90%）和使用类似的磷酸酰胺单体当量（1.5当量/周期）。液相寡聚物合成效率最大化（MELOS）是Exactmer、伦敦玛丽女王大学（QMUL）、CPI和阿斯利康（AstraZeneca）在英国的合作项目，旨在以GC3\的成功为基础。这个为期24个月的项目将重点关注大规模合成低聚物的纳米星筛分平台在工艺效率和可持续性方面的阶段性变化。目前的化学将进一步发展，使用纳米星枢纽和单体具有更好的膜选择性和更高的溶解性。进一步的步骤变化包括在Nanostar筛分过程中集成溶剂回收循环，与SPS技术相比，寻求将总工艺质量强度（PMI）降低40%。溶剂干燥装置将允许过程中除水，将所需的酰胺磷当量降低到接近化学计量值（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，这项工作是为了确保**最高质量的产品以最小的环境影响，并以较低的成本获得**。

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**.