VTv Therapeutics (VTVT) said the US Food and Drug Administration granted orphan drug designation to HPPD, its investigational oral treatment for sickle cell disease.

Preclinical studies conducted at Augusta University in a mouse model showed HPPD was well tolerated, increased fetal hemoglobin, and reduced oxidative stress and red blood cell sickling, vTv said Wednesday in a statement.

The treatment increased fetal hemoglobin in a time- and dose-dependent manner, with effects comparable to or exceeding those of hydroxyurea, the company said.

HPPD's safety and efficacy have not been established, and there is no guarantee it will receive regulatory approval or become commercially available, vTv said.

The company's shares rose 2.2% in after-hours trading.