German drugmaker Bayer garnered support from FDA staff for its submission for approval of riociguat for two forms of pulmonary hypertension, though reviewers recommended clearing the experimental drug at a lower dose than the company sought.
The FDA review document comes ahead of an agency advisory committee meeting next Tuesday, when nonagency experts are expected to weigh in on Bayer's New Drug Application for riociguat as a treatment for both chronic pulmonary thromboembolic hypertension and pulmonary arterial hypertension. This is an important drug for Bayer because, as Bloomberg reported, analysts project annual sales of $498 million by 2017.
Riociguat, which Bayer plans to market as Adempas, has a shot to become the first drug approved for chronic pulmonary thromboembolic hypertension, which is a condition that causes restricted blood flow in the arteries to the lungs for at least 6 months after a patient experiences a clot. According to the Cleveland Clinic, the condition is diagnosed in about 5,000 patients in the U.S. annually. In the separate indication of pulmonary arterial hypertension, Bayer's drug would compete with therapies such as Tracleer from Actelion ($ATLN) and, if approved, the Swiss biotech group's macitentan.
Yet both macitentan and Bayer's riociguat face regulatory scrutiny in the coming months. For riociguat, FDA reviewers noted that up to a third of patients on the 2.5-mg dose Bayer wants approved experienced more low blood pressure events. They recommended approval at 0.5 mg with incremental ascending doses of up to 1.5 mg if needed, saying that Bayer's data package lacked evidence of clinical benefit at the higher dose.
"This drug is approvable so long as its dosing algorithm is modified," Preston Dunnmon, an FDA reviewer, wrote, as quoted by Bloomberg.
The pulmonary hypertension market is perhaps more important for Actelion than for Bayer. Actelion relies on sales of Tracleer for the bulk of its revenue, and the company faces generic competition after the $1.5 billion seller loses patent exclusivity in 2015. Bayer has also been racking up a slate of new drug approvals, which has helped swell drug sales.
The FDA is expected to decide whether to approve macitentan and riociguat by this October.