Development of Kilogram-Scale Convergent Liquid-Phase Synthesis of Oligonucleotides

Oligonucleotide drugs show promise to treat diseases afflicting millions of people. To address the need to manufacture large quantities of oligonucleotide therapeutics, the novel convergent liquid-phase synthesis has been developed for an 18-mer oligonucleotide drug candidate. Fragments containing tetra- and pentamers were synthesized and assembled into the 18-mer without column chromatography, which had a similar impurity profile to material made by standard solid-phase oligonucleotide synthesis. Two of the fragments have been synthesized at similar to 3 kg/batch sizes and four additional tetra- and pentamer fragments were synthesized at >300-g scale, and a 34-mer was assembled from the fragments. Critical impurities are controlled in the fragment syntheses to provide oligonucleotides of purities suitable for clinical use after applying standard full-length product purification process. Impurity control in the assembly steps demonstrated the potential to eliminate chromatography of full-length oligonucleotides, which should enhance scalability and reduce the environmental impact of the process. The convergent assembly and telescoping of reactions made the long synthesis (>60 reactions) practical by reducing production time, material loss, and chances for impurity generation.

Automated summary

A novel convergent liquid-phase synthesis has been developed for manufacturing large quantities of oligonucleotide therapeutics, showing promise for treating diseases affecting millions of people. The method allows for the assembly of an 18-mer drug candidate without the need for column chromatography, resulting in similar purity to standard solid-phase synthesis. The process demonstrates potential for eliminating chromatography in the purification steps, enhancing scalability and reducing environmental impact.