Comprehensive studies on building a scalable downstream process for mRNAs to enable mRNA therapeutics

In recent years, mRNA-based therapeutics have been a fast-growing new class of biologics that can, in principle, encode any protein(s) directly in patients to treat various diseases. mRNA vaccines have been proven to work efficiently, have high potency, and can be rapidly developed and deployed, which is critical for a quick responses in the case of a pandemic. Such agile development is enabled by rapid synthesis of RNA in vitro using recombinant enzymes rather than relying on lengthy and complex cell culture processes. mRNA exhibits physical and chemical properties differing from protein-based therapeutics. It is highly negatively charged and the hydroxyl group makes mRNA less stable and more susceptible to hydrolysis and nucleophilic cleavage. This novel work shares comprehensive studies carried out to compare the performance of various mRNA purification strategies by considering its scalability and critical quality attributes. In addition, the paper provides insights on how to establish a scalable mRNA purification process that consists of ultrafiltration/diafiltration and chromatography steps with good recoveries. Alternative Oligo(dT) based columns were further explored aiming to improve total process recovery. With Oligo(dT) as a capture step, overall recoveries of 70% can be achieved for mRNAs studied here that encode anti-influenza immunoglobulin G monoclonal antibodies.