Efficacy and Safety of Riociguat in Incipient Pulmonary Vascular Disease as an Indicator for Early PAH

This is a randomized, double-blind, placebo-controlled, multicenter, multinational study investigating the effect of riociguat (MK-4836) in patients with early pulmonary vascular disease.

Chronic pulmonary arterial hypertension (PAH) is associated with impaired exercise capacity, quality of life and right ventricular function characterized by an increase of pulmonary vascular resistance (PVR) and pulmonary arterial pressure, leading to right heart insufficiency. Riociguat tratment is approved for both PAH and chronic thromboembolic pulmonary hypertension (CTEPH). Data on early treatment of patients with mildly elevated pulmonary arterial pressures is still scarce but there is evindence that such patients may benefit from early targeted therapy. For instance, in a trial on systemic sclerosis (SSc)-patients with mildly elevated mean pulmonary artery pressure (mPAP) and/or exercise pulmonary hypertension, without significant left heart or lung disease, ambrisentan, an endothelin receptor antagonist resulted in an improvement of PVR as secondary endpoint, which may be of prognostic relevance in this patient cohort and requires further research. Besides its prognostic significance among patients with SSc-APAH, PVR may be an indicator of early pulmonary vascular disease and previous studies proved the positive effects of riociguat on right heart size and PVR (secondary endpoint in phase III studies). Thus, PVR was chosen as primary endpoint of this study aiming to investigate the effect of riociguat (MK-4836) on PVR, clinical parameters, safety and tolerability in patients with early pulmonary vascular disease. Eligible subjects will be randomized in a 1:1 ratio to receive either riociguat or placebo. Medical examinations include medical history, physical examination, electrocardiogram, blood gas analyses, lung function tests, laboratory testing (including NT-proBNP), echocardiography at rest, and right heart catheterization. The prospective period of data collection comprises a 24-week treatment phase diveded into an 8-week titration phase followed by a 16-week main study phase as well as a safety follow-up of 30±14 days.