Prothena reported Phase 1 clinical data indicating a higher incidence of amyloid-related imaging abnormalities with edema (ARIA-E) linked to its PRX012 candidate, an anti-amyloid beta antibody for early Alzheimer’s disease. This increased ARIA rate clouds the drug’s competitive positioning and may impact its future development pathway. The company is assessing next steps to address safety and efficacy profiles in this difficult therapeutic area.