Aron Knickerbocker, CEO of Five Prime Therapeutics (NASDAQ: FPRX), has resigned “to pursue new challenges and opportunities,” the company announced after the market close Thursday. Knickerbocker was promoted to CEO nearly two years ago to succeed founder and longtime CEO Lewis “Rusty” Williams, who became the South San Francisco biotech’s executive chairman.
Five Prime said Thursday that board member William Ringo has been appointed interim CEO while the company searches for a permanent chief executive. Ringo has been a board member since 2014 and chairman of the board since January. Ringo’s experience includes serving as president and CEO of Abgenix, and as senior vice president of business development, strategy, and innovation at Pfizer (NYSE: PFE). He also spent 28 years at Eli Lilly (NYSE: LLY) in a number of executive roles. Ringo will continue serving as chairman of Five Prime’s board.
In January, Five Prime laid off approximately 20 percent of its staff in a corporate shakeup intended to keep its focus on its clinical-stage cancer therapies. Lead drug candidate bemarituzumab is in Phase 3 testing in gastric and gastroesophageal junction cancers with a particular genetic signature.