Bayer Initiates Phase IIIb Study of Riociguat for Pulmonary Arterial Hypertension

Bayer HealthCare has enrolled its first patient in a Phase IIIb pilot study of its riociguat in patients with pulmonary arterial hypertension (PAH) who demonstrate an insufficient response to treatment with PDE-5 inhibitors as a monotherapy or paired with an endothelial receptor agonist (ERA), the German pharma giant said Thursday.

The RESPITE study may provide “the first clinical evidence on the potential clinical benefits of switching these PAH patients to riociguat,” said Bayer spokesman Joerg Moeller.

The open-label, single-arm, international and multi-label study will evaluate 60 patients ages 18 to 70 previously treated with either sildenafil or tadalafil for at least three months. Among its outcome measures will be a change from baseline in patients’ six-minute walk distances over a period of 24 weeks, cardiac index, clinical worsening, nitric oxide biomarkers and quality of life.

Bayer plans to start Phase II studies of the drug later this year for other types of pulmonary hypertension, Reynaud’s disease and differential systemic sclerosis.

Riociguat is an oral soluble guanylate cyclase stimulator that targets one of the key molecular mechanisms behind PAH. It is approved for chronic thromboembolic pulmonary hypertension in the U.S., Canada, Switzerland and Japan and for PAH in the U.S. and Canada. Last month, the EU’s Committee for Orphan Medicinal Products affirmed that riociguat shows significant benefits over existing treatments, Bayer said. — Lena Freund

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