Five Prime Therapeutics, Inc. announced that its Board of Directors has appointed William 'Bill' Ringo as Interim Chief Executive Officer, effective immediately. Mr. Ringo will succeed Chief Executive Officer and Board Member Aron Knickerbocker, who has resigned from the company to pursue new challenges and opportunities. Mr. Ringo will continue to serve as Chairman of Five Prime’s Board of Directors. Mr. Ringo has served as the Chairman of the Five Prime Board of Directors since January 2019 and as a Board Member since October 2014.