Safety, pharmacokinetics and pharmacodynamics of TQC3721, an innovative, dual PDE3 and PDE4 inhibitor, in healthy subjects and patients with chronic obstructive pulmonary disease: Randomised, double‐blind, placebo‐controlled phase I and IIa clinical trials

Background and Purpose TQC3721 is a novel inhaled dual phosphodiesterase (PDE3/4) inhibitor designed to provide bronchodilation and anti‐inflammatory effects for chronic obstructive pulmonary disease (COPD). Experimental Approach First‐in‐human randomised, double‐blind, placebo‐controlled phase I (SAD: 0.2 to 24 mg single dose; MAD: 12 mg once daily (QD) for 7 days in healthy subjects) and phase IIa studies (0.75 to 6 mg once or twice daily for 4 weeks in moderate‐to‐severe patients with COPD) were conducted. Primary outcomes included safety, pharmacokinetics (PKs) and pharmacodynamics (PDs), change from baseline of forced expiratory volume in the first second [FEV 1 ], and FEV 1 at 12 and 24 h post‐dose on days 1 and 28. Key Results TQC3721 was rapidly absorbed (median T max of 0.25 to 0.5 h), mainly by pulmonary absorption rather than gastrointestinal absorption, along with low systemic exposure and lack of significant accumulation. TQC3721 demonstrated favourable safety profiles in healthy subjects and patients with COPD. In patients with COPD, TQC3721 produced rapid and outstanding bronchodilation effect sustained over 12 h post‐administration, with FEV 1 peaking at approximately 2 h post‐dose and returning to baseline levels by 12 h, which supports a twice‐daily dosing regimen for the future, and peak FEV₁ improvements ranging from 186 to 272 ml across dose groups after 4 weeks of treatment. Moreover, twice‐daily 3 and 6 mg regimens were recommended for further clinical study. Conclusions and Implications Pharmacokinetic features, significant bronchodilation effects and overall favourable safety characteristics support further clinical development of TQC3721 as a potential dual‐mechanism therapy for COPD.