Researchers say they have developed a new chromatography method for purifying secretory antibody therapies. The team, from BOKU University in Vienna, claims the new method aims to help purify immunoglobulin A (IgA) to a standard high enough for large-scale production. And, by doing so, they hope to aid the delivery of secretory antibody treatments to respiratory and gastrointestinal patients.
“I think interest has grown [in these treatments] due to the pandemic and the knowledge that respiratory diseases can just happen,” says David Scheich, a PhD student at BOKU’s Institute of Bioprocess Science and Engineering.
“There’s no real market yet [for them], but I think that’s because we’ve only been able to produce them in viable titers in a very short time.”
To help create this emerging market, the team developed a chromatography resin specifically designed to capture secretory antibodies. They reengineered a binding molecule that, like the Protein A used in the capture step for monoclonal antibody manufacture, is found on the surface of bacteria.
The purpose of the ligand was to specifically capture IgA when produced at the grams per liter titers required for commercial manufacturing.
According to Scheich, a macropore resin was used for the capture step for the fully assembled IgA with a size of 400 kilodalton and the smaller (70–80 kilodalton) secretory component, which is the major product-related impurity.
The smaller secretory component could be easily removed from the much-larger IgA antibody later in processing, he says.
“From a bioprocessing point of view, it’s not rocket science. It’s a simple filtration step where you would, I think, be able to get rid of the main impurity that remains after the capture,” he says.
Having developed the new ligand, the team is now looking to optimize it toward being as functional as Protein A.
“There’s definitely more engineering possible,” says Scheich. “There’s a straight path that’s been done before [with Protein A] to get to the [same] point as the most successful modality on the market today for antibodies.”
