Effects of an inhaled soluble guanylate cyclase (sGC) stimulator MK-5475 in pulmonary arterial hypertension (PAH)

Novel therapeutics for pulmonary arterial hypertension (PAH) with improved safety/tolerability profiles are needed to address continued high rates of morbidity/mortality.This Phase 1 study evaluated efficacy/safety of inhaled single-dose MK-5475, an investigational, small-molecule stimulator of soluble guanylate cyclase designed for inhaled delivery via a dry-powder inhaler device, in participants with PAH (Clinicaltrials.gov: NCT03744637). Eligible participants were 18-70 years of age; body mass index ≤35 kg/mMK-5475 was generally well tolerated without systemic side effects on blood pressure or heart rate up to 24 h post dose. With respect to the primary pharmacodynamic outcome, mean reductions in pulmonary vascular resistance ranged from 21% to 30% across 120 μg and 360 μg doses.Treatment with inhaled single-dose MK-5475 showed rapid and sustained reductions in pulmonary vascular resistance and increases in pulmonary blood volume. MK-5475 was generally well tolerated versus placebo without vasodilatory systemic side effects. The promising pulmonary selectivity and favorable safety/tolerability profile of MK-5475 seen in this study of adult participants with PAH lays the foundation for further clinical development.