Ionis Zanvastro Priority Review Voucher Grant Adds $150-350M Commercial Value; PRV Secondary Market Continues to Anchor Rare Disease Program Economics
The Rare Pediatric Disease Priority Review Voucher (PRV) granted to Ionis Pharmaceuticals (NASDAQ: IONS) alongside the Zanvastro (zilganersen) FDA approval Thursday September 3, 2026 for Alexander disease adds substantial commercial value to the launch economics. PRVs have historically sold for $150 to $350 million on the secondary market and can be transferred an unlimited number of times. Recent PRV transactions: Arrowhead Pharmaceuticals sold a PRV for $215 million cash in connection with the plozasiran FCS approval earlier in 2026; other recent PRV sales have priced in the $100-200 million range. Ionis has not yet disclosed plans for the PRV — the company can use it to accelerate FDA review of a future NDA/BLA submission (from standard 10-12 months to priority 6 months) or sell it to another drug developer. The PRV program has faced periodic legislative sunset threats and is currently authorized through December 2026; the incentive continues to drive investment into rare pediatric disease programs where the commercial market alone would not economically justify development.