Horizon Therapeutics plc announced results of a retrospective analysis of the pivotal Phase 2/3 N-MOmentum clinical trial, indicating UPLIZNA may provide durable efficacy and a favorable safety profile for African Americans with NMOSD. These data were presented during the 15th World Congress on Controversies in Neurology (CONy Virtual), Sept. 23-26, 2021. UPLIZNA is the first and only FDA-approved anti-CD19 B-cell depleting humanized monoclonal antibody for the treatment of adult patients with anti-aquaporin-4 (AQP4) antibody positive NMOSD. N-MOmentum consisted of a 28-week randomized controlled period (RCP), in which study participants received UPLIZNA or placebo, followed by an optional open-label period (OLP) during which all participants received UPLIZNA for at least two years. This analysis represents the experience of 20 African Americans who participated in the RCP (15 received UPLIZNA, five received placebo) and the OLP (20 received UPLIZNA). Among African American participants who received UPLIZNA during the RCP and/or OLP, three of 19 had attacks 18, 29 and 104 days after their first UPLIZNA dose. Annualized attack rate (AAR) for African Americans was 0.06 compared with 0.09 in the overall group with any UPLIZNA exposure. Median AAR in the African American group in the two years before enrollment was 1.38. In African American participants, UPLIZNA produced rapid and sustained B-cell depletion, consistent with other N-MOmentum trial participants. During the RCP, African American participants in the UPLIZNA group developed fewer infections (26.7%) than those in the placebo group (60%), although one participant in the treatment arm developed cytopenia that resolved in four weeks. NMOSD is a unifying term for neuromyelitis optica (NMO) and related syndromes. NMOSD is a rare, severe, relapsing, neuroinflammatory autoimmune disease that attacks the optic nerve and spinal cord, as well as the brain and brain stem. Approximately 80% of all patients with NMOSD test positive for anti-AQP4 antibodies. AQP4-IgG bind primarily to astrocytes in the central nervous system and trigger an escalating immune response that results in lesion formation and astrocyte death. Anti-AQP4 autoantibodies are produced by plasmablasts and plasma cells. These B cell populations are central to NMOSD disease pathogenesis, and a large proportion of these cells express CD19. Depletion of these CD19+ B cells is thought to remove an important contributor to inflammation, lesion formation and astrocyte damage. Clinically, this damage presents as an NMOSD attack, which can involve the optic nerve, spinal cord and brain. Loss of vision, paralysis, loss of sensation, bladder and bowel dysfunction, nerve pain, and respiratory failure can all be manifestations of the disease.6 Each NMOSD attack can lead to further cumulative damage and disability. NMOSD occurs more commonly in women and may be more common in individuals of African and Asian descent.