BioWorld International Correspondent

BRUSSELS, Belgium - Using transgenic plants to produce pharmacologically and immunologically active substances "is a promising new technology," according to the European Medicines Evaluation Agency.

The EMEA is developing guidelines on the use of transgenic plants in manufacturing biological medicines for human use, and has agreed on a framework for its scientific experts to move ahead.

The possible advantages, the EMEA said in a just-released concept paper, include the simplicity of plant-based production processes and the avoidance of the need to use mammalian material in growth media. At present, it said, production of recombinant proteins from stable genetically modified plant germ lines would appear to be the only method compatible with European Union regulatory requirements aimed at ensuring adequate control of production and lot-to-lot consistency. Production from transiently infected individual plants remains, for the moment, a less orthodox approach, the EMEA said.

There is a need for regulatory guidance to deal with some of the new questions thrown up by transgenic plant technology, the EMEA said, listing concepts such as the continuing need for standardized definitions of terms such as transgenic plant, line and seed-lot; the unresolved divergence of techniques for culturing and propagating such plants; and the fact that a variety of stages in plant reproductive pathways are amenable to genetic modification. One of the key problems highlighted is ensuring batch-to-batch consistency, which requires that plant cultivation is conducted in a contained environment, with careful control of variables relating to air, soil, light, contamination and use of pesticides and growth promoters.

Downstream processing steps also will need validation for removal of cellulosic and other products of primary plant metabolism, the removal of residual cellular DNA and any secondary products of plant metabolism. A series of controls and tests will be needed to ensure freedom for the final product from potentially harmful viral, bacterial or fungal contaminants of plant origin. The EMEA is planning to start work on its guidance in June.

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