Producing rituximab, marketed as Mabthera, using non-transgenic green plants expands the system’s use beyond vaccines and into the high potential biosimilar monoclonal antibody (mAb) sector.
“The production of functional rituximab in plants suggests that many if not all mAbs can be produced using the iBioLaunch system”, Terence Ryan, senior vice president at iBio, said. Therapeutic proteins and viral antigens for vaccines were the first treatment types producing using the system.
iBio developed a vector system for multi-chain proteins, such as antibodies, to make the green plants express rituximab. Plants produced a balance of heavy and light chains which self-assembled into the mAb structure. iBio then purified the mAb from the plant tissue.
Rituximab produced using the plants underwent a number of preclinical tests to evaluate efficacy. The plant-derived treatment showed similar target cell cytotoxicity and antigen recognition to rituximab produced in mammalian cells.
The potential for low-cost, scalable production of mAbs in green plants has attracted interest on both sides of the Atlantic. US-based iBio’s success follows the start of the first European clinical trial of a mAb produced in transgenic tobacco plants.
A Phase I trial began in July after the UK Medicines and Healthcare products Regulatory Agency (MHRA) approved the study. Entering clinical trials was the culmination of collaboration by industrial and academic partners that began in 2004.
The lack of a regulatory pathway and manufacturing guidelines for plant-produced treatments was one source of delays. Having worked with regulators to find an acceptable process it is hoped gaining approval should be less challenging in the future.