The US Food and Drug Administration (FDA) has granted priority review of Bayer HealthCare's New Drug Application (NDA) riociguat (BAY 63-2521) which is an oral agent being investigated as a new approach to treating different types of pulmonary hypertension.

The FDA grants priority review to medicines that offer major advances in care or that provide a treatment where no adequate therapy exists. Under the Prescription Drug User Fee Act (PDUFA), the FDA aims to complete its review within eight months from the submission of the NDA, rather than the standard 12-month review cycle.

At the beginning of February, Bayer HealthCare submitted riociguat, the first drug to demonstrate efficacy in two distinct forms of pulmonary hypertension (inoperable chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension (PAH)) for regulatory approval in the United States and in the European Union.

“In the pivotal phase III studies, riociguat was shown to be the first drug therapy to demonstrate robust efficacy in two potentially fatal pulmonary hypertension indications,” said Dr Kemal Malik, member of the Bayer HealthCare Executive Committee and Head of Global Development. “To date, no approved pharmacological therapy exists for CTEPH and as a result there is an urgent unmet medical need for patients who are unable to undergo surgery. We hope that we will soon be in a position to provide patients and doctors with a new treatment option.”

The submission is supported by data from the two randomized, double-blind, placebo-controlled pivotal, global phase III studies, namely CHEST-1 and PATENT-1. Results of both studies were presented at the 2012 annual meeting of the American College of Chest Physicians (ACCP) in Atlanta, USA. Both phase III studies with riociguat met their primary endpoint, a change in exercise capacity, after 12- or 16 weeks respectively. Riociguat was generally well tolerated, with a good safety profile.

Bayer HealthCare announced positive data from the interim analysis of the on-going CHEST-2 trial with riociguat, the open-label long-term extension of the pivotal phase III study CHEST-1, at the 5th World Symposium of Pulmonary Hypertension (WSPH) in Nice, France. The results of the CHEST-2 trial support the positive data of the pivotal CHEST-1 trial, showing long-term safety and sustained clinical benefits in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH).

Riociguat was discovered by Bayer and is the first member of a novel class of compounds, the stimulators of soluble guanylate cyclase (sGC).

Pulmonary hypertension (PH) is a severe, progressive and life-threatening disorder in which the pressure in the pulmonary arteries is significantly increased and which can lead to heart failure and death. Patients with PH develop a markedly decreased exercise tolerance and reduced quality of life. The most common symptoms of PH include shortness of breath, fatigue, dizziness and fainting, all of which are worsened by exertion. As the symptoms of PH are non-specific, diagnosis can be delayed by as much as two years. Early diagnosis is essential as a delay in treatment initiation can have a negative impact on survival. Continuous treatment monitoring is then vital to ensure that patients are receiving optimal care for their particular type and stage of disease.

According to the clinical classification of PH (Dana Point), there are five different types of PH based on underlying causes which are: pulmonary arterial hypertension (PAH), pulmonary hypertension owing to left heart disease (e.g. PH-LVD), pulmonary hypertension owing to lung disease and/or hypoxemia (e.g. PH-COPD or PH-ILD), chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary hypertension with unclear multifactorial mechanisms. Currently available pharmacological treatments are only approved to treat one of the five types of PH, pulmonary arterial hypertension. As a result, there is a strong need for more research to improve understanding of how all five types of PH can be treated effectively.

Bayer Healthcare, a subgroup of Bayer AG is a global enterprise with core competencies in the fields of health care, agriculture and high-tech materials.