Sarepta Therapeutics faces an "arduous path” to try to get its gene therapy for Duchenne muscular dystrophy back onto the market, a senior FDA official told STAT.

Shipments will halt by close of business Tuesday evening, the company said. Sarepta had initially rejected the agency’s request, which was issued Friday.

The company refused the FDA’s request and will continue shipping its therapy, Elevidys, to Duchenne patients who can still walk. A pause on shipments to older, non-ambulatory patients remains in place.