Antibodies aren’t just the cornerstone of the human immune response: scientists have used them to create medicines against many diseases such as cancer and COVID-19, thanks to their intricate molecular structures can be customised to enhance or tailor therapeutic effects. For example, studding the surface of antibodies with chains of sugars called N-glycans can make antibody treatments more potent, or help them stick around in the patient longer.
However, mass-producing antibody medicines is no easy feat, given that they must be created in living cells. Currently, the pharmaceutical industry uses specialised cell cultures to manufacture antibodies, which experts say are unreliable when it comes to making the antibodies’ N-glycan ‘coats’.
“To improve N-glycan processing in these cells, genes encoding for glycan-modifying enzymes are traditionally overexpressed via random integration technology,” explained Yuan Sheng Yang, Principal Scientist at A*STAR’s Bioprocessing Technology Institute (BTI). This technique results in highly diverse batches of antibodies which can lead to inconsistencies in how these treatments work in patients.
Seeking to optimise this process, Yang led a group of researchers who developed a targeted gene integration technology. This novel platform uses an enzyme called recombinase which snips two pre-determined sites in the genomes of antibody-expressing cells, before swapping this section out for a specific gene sequence.
Yang’s team used targeted integration as a tool to study the mechanisms by which sugars are attached to antibodies during production. They studied a panel of 42 human genes linked to sugar synthesis, sugar transport and N-glycan chain extension.
Their experiments revealed that turning on a gene called B4GalT1 helped produce antibodies with thick coatings of galactosyl, an N-glycan known to boost the therapeutic function of antibodies. Moreover, the team showed that increasing the expression of a second gene, ST6Gal1, produced highly-sialylated antibodies, which prevents antibodies from being cleared from the body too quickly.
“Targeted integration technology can produce antibodies carrying a diverse range of glycan structures to suit different therapeutic needs,” Yang said, adding that the team still needs to figure out how to boost antibody production yields using the new technique.
“We hope to further improve the current platform to reach the production titre of industry standards for clinical or commercial use,” Yang commented. Future studies will also dive deeper into how various glycan profiles affect the function of therapeutic antibodies.
The A*STAR-affiliated researchers contributing to this research are from the Bioprocessing Technology Institute (BTI).