In 2006, Calistoga Pharmaceuticals was founded as a Seattle-based spin-off from ICOS Corp. that was dedicated to developing targeted therapies to improve the health of patients with cancer or inflammatory diseases.

The company’s lead product candidate, CAL-101, was a first-in-class specific inhibitor of the PI3K delta isoform. In 2011, Gilead Sciences acquired Calistoga for $375 million, plus milestones of $225 million. In 2014, the FDA approved idelalisib (Zydelig) for treatment of patients with relapsed chronic lymphocytic leukemia.