 Since the 1990s, many successful new drugs for the treatment of cancer, autoimmune diseases, and other conditions have been protein-based biotechnology drugs, regulated by the Center for Biologics Evaluation and Research.Many of these drugs are extremely expensive; for example, the anti-cancer drug Avastin costs $55,000 for a year of treatment, while the enzyme replacement therapy drug Cerezyme costs $200,000 per year, and must be taken by Gaucher's Disease patients for life.Biotechnology drugs do not have the simple, readily verifiable chemical structures of conventional drugs, and are produced through complex, often proprietary techniques, such as transgenic mammalian cell cultures.