Riociguat for chronic thromboembolic pulmonary hypertension and pulmonary arterial hypertension: a phase II study

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Abstract
We assessed the therapeutic potential of riociguat, a novel soluble guanylate cyclase stimulator, in adults with chronic thromboembolic pulmonary hypertension (CTEPH; n = 42) or pulmonary arterial hypertension (PAH; n = 33) in World Health Organization (WHO) functional class II/III.In this 12-week, multicentre, open-label, uncontrolled phase II study, patients received oral riociguat 1.0–2.5 mgt.i.d.titrated according to systemic systolic blood pressure (SBP). Primary end-points were safety and tolerability; pharmacodynamic changes were secondary end-points.Riociguat was generally well tolerated. Asymptomatic hypotension (SBP −5from baseline (709 dyn·s·cm−5; p<0.0001). 42 (56%) patients were considered to have experienced drug-related adverse events (AEs; 96% mild or moderate). Dyspepsia, headache and hypotension were the most frequent AEs. Study discontinuation because of AEs was 4%.These preliminary data show that riociguat has a favourable safety profile and improves exercise capacity, symptoms and pulmonary haemodynamics in CTEPH and PAH. Randomised controlled trials are underway.