iBio, Inc. announced that its proprietary iBioLaunch technology for the production of biotherapeutic proteins and vaccine antigens in whole green plants has been used to produce a functional monoclonal antibody copy of rituximab, used in the medical treatment of lymphomas, autoimmune diseases, and transplant rejection. Rituximab is a chimeric mouse-human monoclonal antibody that binds to the CD20 antigen presented on the B-cell surface.

Scientists at iBio’s research and development partner, the Fraunhofer USA Centre for Molecular Biotechnology, have expressed the antibody heavy and light chains in whole plants using another novel iBioLaunch vector system developed for multi-chain proteins like antibodies. The expression of rituximab in plants resulted in a balanced expression of heavy and light chains which self-assembled into the appropriate antibody structure, which was then purified from the plant tissue.

Purified, iBioLaunch-produced rituximab was shown to bind to B lymphocytes from donor blood samples, indicating that it was recognizing its antigen presented on the B-cell surface. In further experiments, plant produced rituximab was incubated at various concentrations with donor Peripheral Blood Mononuclear Cells (PBMC), and shown to cause a dose-dependent depletion of B-cells as measured by flow cytometry staining of another B-cell surface antigen, CD19. At the highest doses tested, greater than 90 per cent of donor B cells were lost from the lymphocyte population, showing that plant-produced rituxmab is able to demonstrate the antigen recognition and target cell cytotoxicity observed with rituximab manufactured in mammalian cell systems. The B-cell cytotoxicity is specific to rituximab, which was demonstrated in experiments that used another plant-produced monoclonal antibody as a control for any plant-specific B-cell depletion activity.

“The production of functional rituximab in plants suggests that many if not all monoclonal antibodies can be produced using the iBioLaunch system,” said Terence Ryan, PhD, iBio’s senior vice president. “This success dramatically extends the commercial opportunities for our technology beyond its previous applications for the production of viral antigens for vaccines, and replacement protein biotherapeutics such as alpha-galactosidase, alpha-1 antitrypsin, and C1 esterase inhibitor.”

iBio develops and offers product applications of its iBioLaunch platform, providing collaborators full support for turn-key implementation of its technology for both proprietary and biosimilar products.