GMP issues for recombinant plant-derived pharmaceutical proteins

Recombinant proteins can be produced in a diverse array of plant-based systems, ranging from whole plants growing in the soil to plant suspension cells growing in a fully-defined synthetic medium in a bioreactor. When the recombinant proteins are intended for medical use (plant-derived pharmaceutical proteins, PDPs) they fall under the same regulatory guidelines for manufacturing that cover drugs from all other sources, and when such proteins enter clinical development this includes the requirement for production according to good manufacturing practice (GMP). In principle, the well-characterized GMP regulations that apply to pharmaceutical proteins produced in bacteria and mammalian cells are directly transferrable to plants. In practice, the cell-specific terminology and the requirement for a contained, sterile environment mean that only plant cells in a bioreactor fully meet the original GMP criteria. Significant changes are required to adapt these regulations for proteins produced in whole-plant systems and it is only recently that the first GMP-compliant production processes using plants have been delivered.