The US FDA has granted orphan drug designation for Arrowhead Research Corporation’s experimental ARC-AAT therapy.

ARC-AAT is the company’s RNAi-based therapeutic candidate currently under evaluation as a viable treatment for Alpha-1 Antitrypsin Deficiency (AATD), a rare genetic disease that severely damages both the lungs and liver of those affected (children and adults alike).

Arrowhead is conducting part B of a Phase 1 study for ARC-AAT in patients with the PiZZ genotype of AATD.