A panel of federal advisers on May 6 lent support to the ChemoCentryx bid for approval of avacopan for a rare and serious autoimmune condition. But they also flagged concerns about both the evidence supporting claims of a benefit for this experimental drug and its safety.
At a meeting of the Food and Drug Administration’s Arthritis Advisory Committee, panelists voted 10-8 on a question of whether the risk-benefit profile of avacopan is adequate to support approval.
ChemoCentryx is seeking approval of avacopan for antineutrophil cytoplasmic autoantibody (ANCA)–associated vasculitis in the subtypes of granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).
Regardless of their vote on this approval question, the panelists shared an interest in avacopan’s potential to reduce glucocorticoid use among some patients with ANCA-associated vasculitis, also called AAV. Mara L. Becker, MD, MSCE, the chair of the FDA’s panel, was among the panelists who said they reluctantly voted no.
Dr. Mara Becker
“It pains me because I really want more steroid-sparing” medicines, said Dr. Becker of Duke University, Durham, N.C., who cited a need to gather more data on avacopan.
Margrit Wiesendanger, MD, PhD, of the Icahn School of Medicine at Mount Sinai, New York, who was among the panelists voting yes, spoke of a need for caution if the FDA approves avacopan.
“Judicious use of this new medication will be warranted and perhaps additional guidance could be given to rheumatologists to help them decide for whom this medication is best,” she said.
Panelists had spoken earlier of avacopan as a possible alternative medicine for people with AAV who have conditions that make glucocorticoids riskier for them, such as those who have diabetes.
Close votes on safety profile, efficacy
The panel also voted 10-8 on a question about whether the safety profile of avacopan is adequate to support approval of avacopan for the treatment of adult patients with AAV.
In addition, the panel voted 9-9 on a question about whether efficacy data support approval of avacopan for the treatment of adult patients with AAV.
The FDA considers the recommendations of its advisory panels, but is not bound by them.
The FDA staff clearly expressed the view that ChemoCentryx fell short with the evidence presented for avacopan approval. Shares of San Carlos, Calif.–based ChemoCentryx dropped sharply from a May 3 closing price of $48.82 to a May 4 closing price of $26.63 after the FDA released the staff’s review of avacopan.
In a briefing prepared for the meeting, FDA staff detailed concerns about the evidence ChemoCentryx is using to seek approval. While acknowledging a need for new treatments for AAV as a rare condition, FDA staff honed in on what they described flaws in the testing of this experimental medicine, which is a small-molecule antagonist of the receptor of C5a, an end product of the complement cascade that acts as a potent neutrophil chemoattractant and agonist.
The FDA usually requires two phase 3 studies for approval of a new medicine but will do so with a single trial in cases of exceptional need, the agency staff said. But in these cases, the bar rises for the evidence provided from that single trial.