The U.S. Food and Drug Administration (FDA) has approved Dawnzera (donidalorsen), developed by Ionis Pharmaceuticals, as the first and only RNA-targeted prophylactic treatment for hereditary angioedema (HAE), a rare genetic disorder characterized by severe swelling attacks. Dawnzera works by targeting and degrading prekallikrein mRNA to interrupt the biochemical cascade that causes these swelling episodes. This marks Ionis' second wholly owned drug asset and the tenth approved antisense oligonucleotide therapy overall. The approval comes amid a competitive landscape including companies such as Takeda and BioCryst. The drug label includes a warning for anaphylaxis, which was not highlighted in earlier clinical study publications. Ionis' approval represents a new option for preventing painful and potentially dangerous swelling attacks in HAE patients.