Regenxbio will once again ask the Food and Drug Administration to review its gene therapy Navsunli, saying Monday agency staff have reversed their view that, before considering an approval, the company might need to run a trial in which some enrollees would receive a placebo.
After discussions over an appeal to the FDA’s rejection, Regenxbio said it is now “aligned” with regulators on “the next steps needed for a potential accelerated approval” of its therapy, which is meant to treat the rare neurodegenerative disease Hunter’s syndrome. The FDA “acknowledged the existing Navsunli clinical data is sufficient” and that the company doesn’t need to expand current trials or initiate new ones.
The announcement marks the latest in a series of U-turns on FDA decisions made under former commissioner Marty Makary and his biologics review chief Vinay Prasad, whose tenures were marked by applicants’ complaints that the agency had retracted previous agreements on the data necessary for review and approval.
In February, the FDA notified Regenxbio that it had rejected the company’s approval application. It also laid out steps Regenxbio would have to take in order to resubmit.
Among the deficiencies called out by the agency was use of a “natural history” analysis that compared trial enrollees’ disease progression to people who’ve been studied in the past, as well as a “surrogate” trial endpoint reviewers found unconvincing. While those practices aren’t used in trials of drugs for common conditions like heart disease or diabetes, the FDA in the past has frequently authorized them in rare diseases because of the small number of patients affected.
Prasad, in particular, was hostile to the use of surrogate endpoints as well as trials that don’t include comparator arms in which enrollees receive placebos.
Regenxbio filed an appeal, and during talks with the FDA staff the company was urged to request what’s called a Type A meeting — the most urgent interaction between a developer and the regulator — to “review existing longer-term biomarker and clinical data,” the company said.
After that meeting, expected in July, Regenxbio will resubmit its application, which the FDA will review on an “expedited” basis.
“We are encouraged by recent signals from the new FDA leadership reinforcing a commitment to address the unique nature of rare diseases and use the accelerated approval pathway to bring transformative therapies to patients with serious, unmet medical needs," said Regenxbio CEO Curran Simpson, in a statement.
Regenxbio joins fellow gene therapy developer UniQure, cancer drugmaker Replimmune and big pharma Sanofi in receiving recent reprieves from Makary-era decisions.
"While there are still some wrinkles to smooth out with FDA based on the justifications provided in the Navsunli [rejection], we think this is a clear indication of a new approach which is significantly more flexible and portends a favorable outcome for Regenxbio and patients with Hunter Syndrome," Sean McCutcheon, an analyst at the investment firm Raymond James, wrote in a note to clients.
Regenxbio shares rose as much as 17% in Monday morning trading.
