24/7 BIOPHARMA - issue 1 / October 2024

SUNRESIN NEW MATERIALS

Innovation in rProtein A ligand design for manufacturing high-performing affinity chromatography media for implementing in mAb purification platforms.

Monoclonal antibodies (mAbs) are immune system proteins that bind to target molecules with high specificity. Since their discovery in the late 1970s, mAbs have become essential in treating diseases such as cardiovascular disorders, autoimmune diseases, cancers, multiple sclerosis, Crohn’s disease and for preventing organ transplant rejection. To maximise therapeutic efficacy and minimise adverse effects, mAbs must be delivered with high purity. After production, mAbs are accompanied by host cell proteins (HCP) and DNA, requiring a robust purification process. mAb purification typically involves centrifugation, filtration and chromatographic techniques, depending on the molecular complexity and impurities present. Typically, mAb purification includes Protein A affinity chromatography followed by one or two ion-exchange steps or multi-modal chromatography.

enabling purification of mAbs and bispecific molecules, increasing purity from 60-70% to 90-95% in a single step. Recombinant expression technology has enhanced Protein A production, while genetic modifications have improved its alkaline stability during use. At Sunresin, we undertook the challenge of optimising Protein A affinity resin and developed a novel recombinant Protein A (rProtein A) for mAb purification. This development involved a multi disciplinary team of biologists, biochemists and polymer chemists, resulting in a new approach to affinity resin design. The newly developed rProtein A is a six-C domain fusion protein ligand based on the natural Protein A peptide sequence. After extensive amino acid mutation screening, 180 potential protein sequences were identified from an amino acid sequence library, with 14 fusion protein candidates showing promising results. One fusion protein was ultimately selected as the primary candidate for further development. Development of rProtein A

Affinity chromatography for mAb purification

Affinity chromatography is a critical step in mAb purification. Protein A resins are widely used,

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TWENTYFOURSEVENBIOPHARMA Issue 1 / October 2024