Arrowhead Pharmaceuticals secured U.S. regulatory approval for plozasiran (Redemplo) to treat familial chylomicronemia syndrome, and immediately positioned the drug at a markedly lower list price than the existing Ionis product. The approval converts Arrowhead into a commercial-stage RNAi company and sets up direct market competition with Ionis, reshaping pricing dynamics in a niche rare-disease category. Arrowhead framed the lower price as a commercial differentiator while highlighting claimed safety and dosing advantages. Industry sources say the move could pressure competitors on pricing and payer negotiations for ultra-rare indications. Manufacturers and payers will watch how rebates, distribution and formulary placement evolve as the product launches. For drug developers, the case underscores how regulatory wins can be paired with aggressive pricing to accelerate uptake — and how RNAi entrants may force incumbents into defensive legal and commercial plays. Payers and specialty pharmacies will likely scrutinize economics and outcomes data closely during initial rollout.