Human protein production in animals, eggs, or milk can leverage commercial high volume food production and the application of well known and well controlled food purification processes. Unfortunately, the potential for infectious agent contamination in xenogeneic animals remains high. Most importantly, the animals used to make the proteins may not be introduced into the food chain either as human food or animal feed supplements. Instead, the carcasses must be destroyed, creating serious financial and environmental concerns. Finally, the best place to make a recombinant protein may be in the person with a protein deficiency.
Gene therapy continues to be of interest.
An even more interesting approach, however, may be the insertion of gene-modified or normal cells into patients. As the recombinant protein industry has matured, so has its intellectual property. Multiple recombinant biological products are now off-patent and those schooled in the much larger chemical drug industry see these as easy targets for generic applications. Biologic products are approved under authority of PHSA section 351, which requires demonstrated safety and efficacy for each biological product before approval. However, approval authority may not be the only problem.