Bayer said that the phase 4 REPLACE trial evaluating Adempas (riociguat) in intermediate-risk adult patients with pulmonary arterial hypertension (PAH) has met its primary endpoint.

The German company said that 41% of PAH patients transitioning to Adempas therapy after inadequate response to  phosphodiesterase-5 inhibitors (PDE5 inhibitors) achieved the composite primary endpoint, which is a clinical improvement in the absence of clinical worsening, compared with 20% in the PDE5i group.

According to Bayer, the composite primary endpoint of the late-stage trial was clinical improvement at week 24 in the absence of clinical worsening that is death from any cause, hospitalisation for worsening PAH, or disease progression.

Riociguat, which was licensed in the US as Adempas, is said to be a stimulator of soluble guanylate cyclase (sGC). To date, it is the only treatment approved in the US with indications in two types of pulmonary hypertension.

The German pharma major said that the safety results of the drug are consistent with its known safety profile.

REPLACE, which expands to Riociguat rEplacing PDE-5i Therapy evaLuated Against Continued PDE-5i thErapy, was a global, multicentre, double-arm, randomised, controlled, trial.

The phase 4 trial was held in 81 sites across 22 countries for 24 weeks to evaluate the clinical impacts of transitioning to Adempas from PDE5i therapy. This was assessed across 226 patients with PAH who showed an inadequate clinical response to stable treatment with PDE5i inhibitors such as sildenafil or tadalafil as monotherapy or in combination with an endothelin receptor antagonist (ERA).

Bayer US medical affairs senior medical director Sameer Bansilal said: “In clinical practice, a considerable proportion of intermediate-risk patients with pulmonary arterial hypertension do not reach or maintain specific treatment goals when treated with a PDE5i-based regimen.