in planta transient recombinant production of a bispecific t-cell engager: blinatumomab

Bispecific t-cell engagers (bites) are increasingly being recognized as promising therapeutic molecules in tumor management. however, these largely artificial and complex antibody-based molecules are often difficult to express in conventional platforms. here, we evaluated the recombinant expression of the approved dual-targeting bispecific t-cell engager blinatumomab (blin) for its production in plants. a highly potent viral vector carrying the coding sequence of blin with a his tag was used for transiently expressing blinatumomab in nicotiana benthamiana. four days post-dna construct delivery, immunoblotting exhibited blin-specific signals in total soluble proteins (tsp) as well as in the intercellular fluid (if), indicating secretion of the recombinant protein to the extracellular space. co-expression of an rna silencing suppressor (p19) increased blin-specific signals. while ni-nta purification from tsp resulted in insufficient blin quality, if-derived blin was eluted as a single band at the correct molecular weight. the yield of if-blin was approximately 15 µg/g fresh leaf weight, which is ten times lower than usually obtained for monoclonal antibodies (mabs). chromatographic profiling of if-blin exhibited significant amounts of unwanted high molecular weight forms next to the targeted monomeric fraction. after purification of this fraction, the functional activity of if-blin was confirmed by binding to cells expressing the targeted antigens cd3 or cd19. collectively, we showed the successful production of functionally active blin in plants. further optimization steps are required to improve the yield and quality of plant-produced blin.