Author Archives: Alan K. Hunter

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Clearance of Persistent Small-Molecule Impurities: Alternative Strategies

Small-molecule impurities that bind to and copurify with protein biopharmaceuticals traditionally have been removed using bind-and-elute (BE) chromatography. However, that approach may be undesirable for a number of reasons. For instance, it may present a facility-fit challenge or provide a lower process yield than what is acceptable. A common scenario in which BE chromatography may be undesirable is in removal of unreacted conjugation reagents. Bioconjugates represent an important and growing class of pharmaceuticals that include PEGylated proteins, vaccines, and antibody–drug…

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Bioconjugation Reaction Engineering and Kinetics Simulation

Bioconjugates represent an important and growing class of pharmaceuticals that include PEGylated proteins, vaccines, and antibody-drug conjugates (ADCs) (1–8). Numerous protein conjugation techniques exist (9). Among the more important conjugation chemistries used for protein therapeutics are N-hydroxysuccinimide (NHS), aldehyde, and maleimide (10–13). To date, process development of industrial biopharmaceutical conjugation reactions has largely been empirical in nature. Typically, many experiments testing different reaction parameters are required to identify optimal process conditions. In some instances, nonmechanistic statistical models can be used,…