Purification of protein therapeutics via high-affinity supramolecular host–guest interactions

Efficient purification is crucial to providing large quantities of recombinant therapeutic proteins, such as monoclonal antibodies and cytokines. However, affinity techniques for manufacturing protein therapeutics that use biomolecule-conjugated agarose beads that harness specific biomolecular interactions suffer from issues related to protein denaturation, contamination and the need to maintain biomolecule-specific conditions for efficient protein capture. Here, we report a versatile and scalable method for the purification of recombinant protein therapeutics. The method exploits the high-affinity and controllable host–guest interactions between cucurbit[7]uril (CB[7]) and selected guests such as adamantylammonium. We show that the Herceptin (the brand name of trastuzumab, a monoclonal antibody drug used to treat breast cancer) and the much smaller cytokine interferon α-2a can be purified by site-specifically tagging them with adamantylammonium using the enzyme sortase A, followed by high-affinity binding with CB[7]-conjugated agarose beads and the recovery of the protein using a guest with a stronger affinity for CB[7]. The thermal and chemical stability of CB[7] beads and their scalability, recyclability and low cost may also make them advantageous for the manufacturing of biosimilars.