Exclusive | FDA Gives Third Rare-Disease Drug Another Shot, Regenxbio Says

RGNX plans to refile its gene therapy application for a fatal brain disease after the FDA removed a key clinical trial obstacle. The agency dropped its demand that the company include a placebo arm in its study, clearing the path for Regenxbio to resubmit without requiring some patients with the rare condition to go untreated.

The original application stalled over the FDA's insistence on a placebo-controlled trial design—a requirement the company and patient advocates argued was unethical for a fatal disease with no existing treatment. The agency's reversal marks a significant shift in the regulatory pathway for the therapy.

Regenxbio did not disclose a timeline for the refiling, but the removal of the placebo requirement eliminates what had been the primary regulatory hurdle. The gene therapy targets a rare, fatal brain disease, though the company has not provided updated enrollment or efficacy data in this announcement.

The decision signals potential regulatory flexibility for rare-disease gene therapies where equipoise concerns make traditional placebo trials problematic.