Plexxikon is an American drug discovery company based in South San Francisco, California. It was co-founded in 2001 by Joseph Schlessinger of Yale University, and Sung-Hou Kim of the University of California, Berkeley. It uses a proprietary structural biology-based platform called Scaffold-Based Drug Discovery to build a pipeline of products in multiple therapeutic areas. This discovery process integrates multiple technologies, including structural screening as one key component, that it hopes will give a significant competitive advantage over other approaches. In April 2011, Plexxikon was acquired by the Japanese pharmaceutical company Daiichi Sankyo for $805 million and an additional $130 million in potential milestone payments. Daiichi Sankyo announced the shutdown of Plexxikon in 2022.

Drug pipeline