AstraZeneca and its global biologics research and development arm, MedImmune, announced that the US Food and Drug Administration (FDA) has granted Orphan Drug Designation for the investigational anti-CD19 monoclonal antibody, MEDI-551, for the treatment of patients with neuromyelitis optica (NMO) as well as neuromyelitis optica spectrum disorders (NMOSD). Developed by MedImmune, MEDI-551 is currently in Phase IIb clinical development for NMO.