Bayer halts midstage riociguat study after serious safety concerns

Bayer Cross

Bayer has terminated its Phase II study of riociguat in patients with pulmonary hypertension associated with idiopathic interstitial pneumonias (PH-IIP) with “immediate effect.”

The decision, prompted by the recommendation of an independent safety Data Monitoring Committee (DMC), came after it observed that patients taking Bayer’s med were “at a possible increased risk for death and other serious adverse events,” as compared to patients in the placebo group.

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 a statement from Bayer.

It added that the patients in this trial will be “continuously monitored for safety” immediately after stopping treatment and for a period of at least four months.

Bayer said that it 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," the German drugmaker explained in its release.

Riociguat has been licensed in the U.S. as Adempas since 2013 to treat two forms of pulmonary hypertension: chronic thromboembolic pulmonary hypertension after surgery or patients who cannot undergo surgery, and in patients with PH of unknown causes.

It works as a stimulator of soluble guanylate cyclase, and Bayer was hoping to add to its license with this third indication. In total, there are five types of pulmonary hypertension based on the different underlying causes.

"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," said Dr. Joerg Moeller, member of the Bayer pharmaceuticals executive committee, in the release. "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. 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."

- see the release