The FDA has asked for an assessment of the safety of Regeneron and Sanofi’s cholesterol drug alirocumab, giving investors cause for concern.
Shares in both companies came under pressure after a filing by Sanofi revealed that the US regulator is investigating whether the PCSK9 inhibitor has potential for “neurocognitive adverse events.”
While Sanofi and Regeneron were affected most by the news, the 20-F form filed with the US Securities & Exchange Commission (SEC) suggests the FDA is concerned about the safety of the entire PCSK9 inhibitor class, which includes candidates from Amgen, Lilly, Pfizer, Roche and Alnylam.
Similar concerns have been voiced in the past about the potential for statin drugs to cause neurocognitive effects, such as memory loss, forgetfulness and confusion. While these potential side effects are mentioned on statin labelling, the FDA considers the clear benefits of the class in in preventing heart disease outweigh the risks.
“Neither company knows the circumstances under which the FDA became aware of these adverse events or whether [they] were observed with a drug candidate tested as monotherapy or in combination with a statin or other cholesterol-lowering agent,” says the statement.
The FDA wants Sanofi and Regeneron to review clinical data from trials of alirocumab, and also gauge the feasibility of putting a monitoring system in place in the ongoing registration trials of the drug.
Analysts at Credit Suisse downplayed the news, noting that the FDA has not asked for any suspension in trial enrolment or change the enrolment criteria. In fact, they note that neurocognitive effects have been reported by Amgen from trials of its evolocumab candidate.
“Regeneron and Sanofi will have over 5,000 patient years of randomised data in their phase III programme, not including the outcome studies, which is likely sufficient to make a proper safety assessment,” they write.
Alirocumab (also known as REGN727) has shown very positive activity in phase III trials reported to date, outperforming rival drug Zetia (ezetimibe) from Merck & Co as a monotherapy. Analysts have predicted that the leaders in the PCSK9 inhibitor class could achieve multibillion dollar sales at peak, despite competition from low-cost generic statins.