FDA reverses course on Regenxbio's rare-disease gene therapy, backs accelerated approval path

Regenxbio (RGNX) shares jumped 16 per cent after the company said the US Food and Drug Administration had indicated that existing data for its rare-disease gene therapy could support an accelerated approval application, reversing course months after declining to approve the treatment.

The decision is the latest in a series of regulatory reversals that have raised hopes the FDA may be taking a more flexible approach to therapies for rare diseases. uniQure (QURE) said the FDA had reversed course on its gene therapy for Huntington's disease, clearing the path for an accelerated approval filing after previously calling for a new trial. Separately, Replimune (REPL) said in May that it planned to seek approval for its experimental skin cancer drug for a third time after reaching an agreement with the regulator.

Eliana Merle, an analyst at Barclays, said the shift and other recent changes in FDA stance signaled increased flexibility, adding that despite senior leadership being in flux, the agency was likely to be more friendly to industry moving forward.

The FDA's latest feedback marks a turnaround for Regenxbio, after the agency declined to approve Navsunli, its experimental treatment for Hunter syndrome, citing uncertainty over the trial design. Navsunli is being developed as a one-time gene therapy for Hunter syndrome, or MPS II, a rare inherited disorder that affects physical and cognitive development.

Sean McCutcheon, an analyst at Raymond James, said that while some wrinkles remained based on the justifications set out in the Navsunli complete response letter, the development signaled a significantly more flexible approach that portended a favorable outcome for Regenxbio and patients with Hunter syndrome.

The company said the FDA had now indicated it would not need to enroll additional patients or conduct new studies, including a previously requested placebo-controlled trial. Regenxbio plans to meet with the agency in July and expects to resubmit its application in the third quarter, with the FDA reviewing the resubmission on an expedited basis.