A three-decade monopoly: How Amgen built a patent thicket around its top-selling drug

Three decades ago, a scientist at the University of Texas named Bruce Beutler asked the U.S. government to grant him a patent for a new invention.

Beutler, who would later win the Nobel Prize for his research, had come up with a way to shut down certain types of inflammation in cells. His discovery became the foundation of the arthritis drug Enbrel, among the highest-selling pharmaceutical products in history and the backbone of one of the industry’s largest companies, Amgen.