Inhaled JAK inhibitor GDC-0214 reduces exhaled nitric oxide in patients with mild asthma: A randomized, controlled, proof-of-activity trial

Background The Janus kinase (JAK) pathway mediates the activity of many asthma-relevant cytokines, including IL-4 and IL-13. GDC-0214 is a potent, inhaled, small-molecule JAK inhibitor being developed for the treatment of asthma. Objective We sought to determine whether GDC-0214 reduces fractional exhaled nitric oxide (F eno ), a JAK1-dependent biomarker of airway inflammation, in patients with mild asthma. Methods We conducted a double-blind, randomized, placebo-controlled, phase 1 proof-of-activity study in adults with mild asthma and F eno higher than 40 parts per billion (ppb). Subjects were randomized 2:1 (GDC-0214:placebo) into 4 sequential ascending-dose cohorts (1 mg once daily [QD], 4 mg QD, 15 mg QD, or 15 mg twice daily). All subjects received 4 days of blinded placebo, then 10 days of either active drug or placebo. The primary outcome was placebo-corrected percent reduction in F eno from baseline to day 14. Baseline was defined as the average F eno during the blinded placebo period. Pharmacokinetics, safety, and tolerability were also assessed. Results Thirty-six subjects (mean age, 28 years; 54% females) were enrolled. Mean F eno at baseline across all subjects was 93 ± 43 ppb. At day 14, placebo-corrected difference in F eno was −23% (95% CI, −37.3 to −9) for 15 mg QD and −42% (95% CI, −57 to −27.4) for 15 mg twice daily. Higher plasma exposure was associated with greater F eno reduction. No dose-limiting adverse events, serious adverse events, or treatment discontinuations occurred. There were no major imbalances in adverse events or laboratory findings, or evidence of systemic JAK inhibition. Conclusions GDC-0214, an inhaled JAK inhibitor, caused dose-dependent reductions in F eno in mild asthma and was well tolerated without evidence of systemic toxicity.