The trial will assess the clinical effects of riociguat in patients with pulmonary arterial hypertension (PAH) who show an insufficient response to treatment with phosphodiesterase-5 inhibitors (PDE-5i) either as monotherapy or in combination with an endothelin receptor antagonist (ERA).
About 60 PAH patients pre-treated with either sildenafil or tadalafil for at least three months, and who show an insufficient clinical response to PDE-5 inhibitor therapy will be treated with riociguat for 24 weeks after a wash-out phase in the RESPITE trial.
Bayer HealthCare member of the Executive Committee and head of Global Development Joerg Moeller said a large proportion of PAH patients treated with PDE-5 inhibitors does not reach or maintain specific treatment goals.
"The exact scientific reason for this insufficient response to treatment is still unknown. However, riociguat potentially has an advantage over PDE-5 inhibitors as the soluble guanylate cyclase (sGC) stimulator works independently from endogenous nitric oxide (NO) levels," Moeller said.
"The RESPITE study may provide the first clinical evidence on the potential clinical benefits of switching these PAH patients to riociguat."
In the major Phase III clinical trial PATENT-1, riociguat was shown to be the first oral treatment with robust efficacy across multiple clinically relevant endpoints in patients with PAH, either as a monotherapy or in combination with ERA or prostacyclin analogue (PCA) therapies.
The company said that until now no other oral drugs, including PDE-5 inhibitors, have been able to show this.
Till date, there is no clinical data available to inform physicians if replacement of PDE-5 inhibitors with riociguat is safe and if it is related with clinically relevant improvements in patients who are not at treatment goal with PDE-5 inhibitors.
The company said that outcome variables being evaluated in the RESPITE trial include changes in 6MWD, cardiac index, Quality of Life, WHO FC, clinical worsening, and other disease-related parameters as well as nitric oxide biomarkers.
The results of RESPITE trial are intended to be used as the basis for further investigations.
Image: Bayer HealthCare’s research site at Berlin, Germany. Photo: courtesy of Bayer AG.