Although antibody-drug conjugates (ADCs) offer great promise as therapeutics, they’re not easy to make. Typically, cells, such as Chinese hamster cells (CHOs), are used to make a monoclonal antibody through bioprocessing, and then chemical synthesis is used to produce the drug. After that, individual processes are used to purify the monoclonal antibody and the drug, which can then be combined to make an ADC. Instead of this multistep process, Johannes Felix Buyel, PhD, professor of downstream processing at the University of Natural Resources and Life Sciences, Vienna (BOKU), Austria, makes similar combinations in one go with plants.
In a recent study, Buyel and his colleagues described a plant-based process for making recombinant immunotoxins (RITs), which consist of a targeting protein connected to a toxin that can be designed to kill cancer cells or viruses. As Buyel says, “You can produce these inherently toxic molecules in a single biotechnological system without the need for intermediate purification and chemical coupling as is done for ADCs.”
Buyel and his colleagues explained that they “used Nicotiana benthamiana and N. tabacum plants as well as tobacco BY-2 cell-based plant cell packs (PCPs) to produce effective RITs targeting CD64 as required for the treatment of myelomonocytic leukemia.”
When asked about the main challenges of using plants to make recombinant immunotoxins, Buyel says: “Probably the expression levels should be improved.” Nonetheless, Buyel believes that a commercial bioprocessor would benefit from using a plant-based approach to making RITs. To do that, Buyel says, “It would take the will and courage to initiate change—similar to e-mobility, where established manufacturers were outrun by a newcomer that dared to implement a new technology.”
