Bulk production of the antiviral lectin griffithsin

Fuqua, Joshua L.; Hamorsky, Krystal; Khalsa, Guruatma; Matoba, Nobuyuki; Palmer, Kenneth E.

A critical area of therapeutic protein development related to storage, production and delivery-site, that is often overlooked at the laboratory scale, is amino acid modifications of the protein product including oxidation, deamidation, glycation. Progressive modifications of a protein over time will become increasingly problematic because the identity of the API is not fixed, particularly when such modifications affect product safety and/ or efficacy. Oxidation of a PMP can occur in planta, during production, storage or upon contact with biological fluids. A mixed nonoxidized and oxidized product is likely to be seen by FDA as a degradation product or an impurity, and the FDA requires that an impurity be characterized. Presence of oxidized product may also raise concerns regarding immunogenicity (Chirino et al., 2004; Singh, 2011) . Propensity of a biopharmaceutical to oxidize could complicate the required pharmacology and toxicology studies, as it may necessitate evaluation of toxicity of the oxidized and nonoxidized products, as well as generation of stability and activity profiles of homogenic and heterogenic products. Oxidative products should therefore be identified and characterized early in the development process to avoid the additional risk, time and economic costs of bridging studies. There are several options for handling the presence of an oxidized impurity. One option, for handling a mixed product, is to fully oxidize the API. If a fully oxidize product is produced, testing will have to be performed to ensure the product is fully oxidized and does not leave a nonoxidized form as an impurity; that the oxidized product does not alter activity; that the oxidized product does not form aggregates; and that the oxidized product will perform adequately in in vivo safety studies.