[_yb2s]

Yes, in principle but there are huge limitations and challenges to using a protein as a drug in living organisms. It has to be injected to avoid digestion, and a protein can't just pass into a cell, it needs to get in somehow. Current peptide drugs like insulin are identical to, or closely mimic natural small peptide hormones that bind to receptors on the outside of a cell. However, there is a possibility of using gene therapy to directly express a novel protein drug inside of the cell. A novel protein is also likely to trigger an immune response- so that type of gene therapy is mostly useful when that is actually desired, e.g. as a vaccine.