Bayer Pharmaceuticals is terminating its Phase II study investigating riociguat in patients with pulmonary hypertension associated with idiopathic interstitial pneumonias (PH-IIP) (NCT02138825) with immediate effect, according to a company news release. The decision was based on a recommendation of an independent Data Monitoring Committee (DMC), an independent committee which monitors the safety of patients during the course of the study.

In the ongoing review of the data, the DMC observed that patients receiving riociguat were at a possible increased risk for death and other serious adverse events as compared to patients in the placebo group.

Riociguat, licensed in the US as Adempas (riociguat), is a stimulator of soluable guanylate cyclase (sGC) and is the only treatment approved in the US for use in two types of pulmonary hypertension (WHO Groups 1 and 4).

The DMC did not identify any specific cause or common feature among the patients who died except that many appeared to have more serious and advanced underlying lung disease than the study population as a whole, according to the news release. The patients in this trial will be continuously monitored for safety immediately after stopping treatment and for a period of at least four months.

PH-IIP is a serious and rare disease. According to the clinical classification system of pulmonary hypertension (PH), there are five types of PH based on the different underlying causes (Nice Classification 2013)i. While PH-IIP belongs to Group 3, the etiology and patient characteristics of this type of PH are distinct from other types of PH. Patients with PH-IIP are a high-risk patient population who suffer both from pulmonary hypertension and idiopathic interstitial pneumonias. Prognosis is poor as there are no approved treatments.ii The unmet medical need is high with an estimated mortality rate of over 20% within one year.iii

Pulmonary arterial hypertension (PAH) is classified as PH Group 1, and CTEPH is classified as PH Group 4.

The positive benefit-risk profile of riociguat in its approved indications based on a large, controlled clinical database and supported by the available postmarket pharmacovigilance information remains unchanged. Bayer is closely monitoring the safety and efficacy of riociguat on an ongoing basis. Medical monitoring of safety in other ongoing studies with riociguat in other patient populations supports the continuation of those studies.

“We understand that the need to terminate the study in PH-IIP is very disappointing for patients suffering from this disease, as well as for their doctors and healthcare providers. There is a significant unmet medical need for PH-IIP patients as there are no approved treatments, and finding an effective treatment remains a challenge,” said Dr Joerg Moeller, Member of the Bayer Pharmaceuticals Executive Committee and Head of Global Development. “Bayer remains committed to identifying new therapeutic options and to improving the lives of patients in disease areas where there is a high unmet medical need such as pulmonary hypertension.”