Production of Pharmaceutical Compounds in Plants
Plants are gaining widespread acceptance as a suitable system for the large-scale production of recombinant proteins. As molecular farming has come of age, there have been technological developments on many levels, including transfection methods, control of gene expression, protein targeting, the use of different crops as production platforms , and modiﬁcations to alter the structural and functional properties of the recombinant product. Over the last few years, there has been a continuing commercial development of novel plant-based expression platforms accompanied by signiﬁcant success in tackling some of the limitations of plants as bioreactors, such as low yields and inconsistent product quality that have limited the approval of plant-derived pharmaceuticals. Indeed, one of the most important driving factors has been yield improvement, as product yield has a signiﬁcant impact on economic feasibility. Strategies to improve the recombinant protein yield in plants include the development of novel promoters, the improvement of protein stability and accumulation, and the improvement of downstream processing technologies . Attention is now shifting from basic research towards commercial exploitation, and molecular farming is reaching the stage at which it may challenge established production technologies based on bacteria, yeast, and cultured mammalian cells. There are already several plant-produced proteins on the market 
including one at a large scale . Several plant-derived recombinant pharmaceutical proteins are reaching the ﬁnal stages of clinical evaluation, and more are in the development pipeline. In this chapter, I highlight recent progress in molecular farming, its potential for commercial drug development and production, and the potential impact in developing countries.