What is new about Rio?

This issue of the European Respiratory Journal includes the results of three different studies of riociguat, a soluble guanylate cyclase stimulator, for the treatment of pulmonary hypertension [1–3]. As the first drug in a novel class for the treatment of pulmonary hypertension, riociguat has raised hopes of an expanded drug armamentarium against the still incurable diseases of pulmonary arterial hypertension (PAH) and surgically inaccessible (or persistent post-operative) chronic thromboembolic pulmonary hypertension (CTEPH). Two of these studies are long-term extension studies from pivotal phase III trials: CHEST-1 (Chronic Thromboembolic Pulmonary Hypertension Soluble Guanylate Cyclase–Stimulator Trial 1) [4] and PATENT-1 (Pulmonary Arterial Hypertension Soluble Guanylate Cyclase–Stimulator Trial 1) [5]. The third study (PATENT PLUS) studied the safety and efficacy of the combination of riociguat and the phosphodiesterase (PDE)-5 inhibitor, sildenafil.