The U.S. Food and Drug Administration granted Prevail Therapeutics Inc.'s gene therapy PR006 an orphan drug designation to treat frontotemporal dementia patients with a GRN gene mutation.

The progressive brain disorder can affect behavior, language and movement. It is one of the most common causes of dementia in people under the age of 65 and affects about 50,000 to 60,000 patients in the U.S. About 5% to 10% of these patients have a GRN mutation.

PR006 is one of the New York-based company's gene therapies based on adeno-associated viruses, which it uses to modify genes in cells to cure diseases. Viruses used in this process are harmless as most people carry them already. Lonza Group Ltd. and Prevail have been collaborating since 2018 in developing Prevail's gene therapy programs based on adeno-associated viruses, including PR006 for treating various neurodegenerative disorders.

The regulator's orphan drug designation encourages companies to develop cures for rare diseases by offering tax reductions, fee exemptions and a license to be the sole sellers of approved treatments for seven years.

In a Dec. 16 press release, Prevail's founder and CEO, Asa Abeliovich, said the company plans to bring PR006 "into the clinic" in the first half of 2020.

There are no approved therapies to treat frontotemporal dementia.

Prevail Therapeutics' stock was up 14.42% to $17.54 in after-hours trading Dec. 16.