Riociguat for pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: Results from a phase II long-term extension study

Science and Research

BACKGROUND: Riociguat was well tolerated and improved exercise and functional capacity in patients with pulmonary arterial hypertension (PAH) and inoperable chronic thromboembolic pulmonary hypertension (CTEPH) in a 12-week Phase II trial. We present final data from the long-term extension phase of this study. METHODS: During this multicenter, open-label, uncontrolled long-term extension study, riociguat dose could be changed at the physician's discretion (range 0.5-2.5 mg three times daily). The primary outcome was long-term safety and tolerability of riociguat; secondary outcomes included 6-minute walking distance, World Health Organization functional class, survival, and clinical worsening-free survival. RESULTS: Sixty-eight patients (inoperable CTEPH, n = 41; PAH, n = 27) entered the long-term extension. Median treatment duration at the final data cut-off was 77 months. The most common adverse events were nasopharyngitis (57%) and peripheral edema (37%). Three patients (4%) experienced serious adverse events of hemoptysis: two moderate, one severe, none fatal or considered drug-related. At Month 48, 6-minute walking distance increased from baseline by 69 +/- 105 m, and World Health Organization functional class improved/stabilized/worsened versus baseline in 50/45/5% of patients. Three-year survival and clinical worsening-free survival were 91% and 49%, respectively (with patients censored if they withdrew without experiencing an event). Starting a new PAH treatment was the most frequent clinical worsening event. CONCLUSIONS: Improvements in exercise and functional capacity were maintained at 4 years in patients remaining on treatment, with no new safety signals identified. These data support riociguat as a long-term treatment option for PAH and inoperable CTEPH. TRIAL REGISTERED AT: ClinicalTrials.gov. REGISTRATION NUMBER: NCT00454558.