The FDA has granted PhaseRx Inc. orphan drug designation for PRX-OTC, an intracellular enzyme replacement therapy that can potentially treat ornithine transcarbamylase deficiency (OTCD) in children. The rare liver disease is an inherited single-gene deficiency that can lead to high levels of ammonia in the blood.

In a preclinical model of OTCD, PRX-OTC appeared to lower blood ammonia in 100% of the mice that were treated. Officials with PhaseRx intend to file an investigational new drug application for PRX-OTC in 2017.

“PRX-OTC is the first of 3 drugs in development using our Hybrid mRNA Technology, and we believe it has the potential to correct the disease in children, a population that could particularly benefit from treatment for this rare disease,” Robert W. Overell, PhD, president and chief executive officer, said in a press release.

In July 2016, PhaseRx officials announced that they had made progression with PRX-OTC. The company indicated that it plans to produce phase 2a and 2b clinical proof-of-concept data for the product in 2018.

“We are excited to name PRX-OTC as our lead drug product candidate and look forward to advancing its development for the treatment of this rare genetic disorder,” said Dr. Overell, in a press release. “We are also delighted with the results of the proof-of-concept study in our ASLD program and believe these data show that our platform is applicable to the treatment of other single-gene inherited disorders of metabolism in the liver.”