Plexxikon is an American drug discovery company based in South San Francisco, California.

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.

[citation needed][1] 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.

[2][3][4] Daiichi Sankyo announced the shutdown of Plexxikon in 2022.