Bayer HealthCare announced data from the Phase 3 CHEST-1 trial evaluating its investigational drug riociguat in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH) or with persistent or recurrent pulmonary hypertension (PH) after surgery. 

CHEST (Chronic Thromboembolic Pulmonary Hypertension sGC-Stimulator Trial) was a trial designed to assess the efficacy and safety of oral riociguat in the treatment of patients with either inoperable chronic thromboembolic pulmonary hypertension or pulmonary hypertension (PH) which has persisted or reoccurred after pulmonary endarterectomy (PEA). CHEST was a multi-center, multi-national program with active centers in 26 countries. The program includes a randomized, double-blinded, placebo-controlled trial phase (CHEST-1) and an open label extension trial phase (CHEST-2).

In the CHEST-1 study, 261 patients were randomized and treated with either riociguat or placebo orally for 16 weeks. Riociguat was titrated, over a period of eight weeks in doses of 0.5mg increments, from 1mg up to 2.5mg, three times a day. After the titration phase, patients were followed up for another eight weeks on their last dose to complete CHEST-1. Patients from both arms then had the option of participating in the open label extension study (CHEST-2) after completing an eight-week blinded sham titration.

The CHEST-1 study met its primary endpoint by demonstrating a statistically significant improvement in the six-minute walk distance (6MWD). In the study, patients treated with riociguat showed an improvement of 46 meters (95% CI [25–67 meters] P<0.0001) vs. placebo. Riociguat also showed statistically significant improvements in select secondary endpoints, including pulmonary vascular resistance (PVR) (P<0.0001), N-terminal prohormone brain natriuretic peptide (NT-proBNP) (P<0.0001) and WHO functional class (FC) (P=0.0026).

Riociguat (BAY 63-2521) is an investigational oral soluble guanylate cyclase (sGC) stimulator.  

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