Effect of Andecaliximab on FEV1 in Adults With Cystic Fibrosis

The primary objective of this study is to evaluate the effect of andecaliximab (GS-5745) on pre-bronchodilator forced expiratory volume in 1 second (FEV1) % predicted in adults with cystic fibrosis (CF) after 8 weeks of treatment. There will be 2 parts to this study. In Part 1, andecaliximab 600 mg or placebo will be administered for 8 weeks. In Part 2, andecaliximab 300 mg, 150 mg, or placebo will be administered for 8 weeks. Part 2 will be initiated after completion of Part 1.