A dual phosphodiesterase inhibitor delivered by dry powder inhaler met its primary endpoint in a Phase IIb randomized trial in chronic obstructive pulmonary disease (COPD), providing the first controlled efficacy data for AN01.
Redwood City, California-based AirNexis Therapeutics presented results from study HSK39004-T1-202 at the 2026 European Respiratory Society Congress in Barcelona. The trial, conducted in China by AirNexis' partner Haisco Pharmaceutical Group, randomized 195 symptomatic COPD patients — 90 on single bronchodilator background therapy and 105 on dual bronchodilator therapy — in a 1:1:1 ratio to AN01 0.75 mg, AN01 1.5 mg, or placebo for four weeks. Both doses met the primary endpoint of change from baseline in FEV₁ area under the curve from 0 to 12 hours post-dose (ΔFEV₁ AUC₀₋₁₂h) at Week 4, with treatment differences of 116 mL for the 0.75 mg dose and 127 mL for the 1.5 mg dose versus placebo.
In patients already receiving dual bronchodilator therapy — a population with limited remaining pharmacological options — both doses still produced improvements of 74 mL and 75 mL, respectively. Among patients on single bronchodilator therapy, the improvements were larger at 164 mL and 189 mL. No treatment-related adverse events were reported in the 0.75 mg group, the dose under investigation in the Phase III program; the 1.5 mg group recorded a treatment-related adverse event rate of 6.1%, compared with 7.9% in the placebo group. AN01 inhibits both PDE3, driving bronchodilation through smooth muscle relaxation, and PDE4, reducing inflammatory mediator release — a dual mechanism designed to provide additive benefit on top of existing bronchodilator regimens.