FDA Rejects PTC's Vatiquinone Application for Friedreich's Ataxia, Requests Further Studies on August 20, 2025 Clinical Research Complete Response Letter drug efficacy factor IX Friedreich 's ataxia rejection United States Food and Drug Administration vatiquinone +
FDA Rejection Derails PTC Therapeutics' Rare Disease Hopeful on August 19, 2025 Clinical Trials concerns Effectiveness factor IX Failure (biologic function) Friedreich 's ataxia Rare Diseases rejection Response process United States Food and Drug Administration vatiquinone +