Efficacy and safety of sepiapterin versus sapropterin in patients with phenylketonuria: Results from the Phase 3, randomized, crossover, open-label, active-controlled AMPLIPHY trial

Abstract

Aim AMPLIPHY is the first Phase 3 study comparing sepiapterin versus sapropterin in children and adults with phenylketonuria (PKU). Methods AMPLIPHY was an international, Phase 3, two-part, open-label study in participants with PKU aged ≥2 years. Participants responsive to sepiapterin (60 mg/kg/day) in Part 1 (≥20% reduction in blood phenylalanine [Phe]) entered Part 2, a crossover treatment period, and were randomized 1:1 to alternative treatment sequences of sepiapterin (60 mg/kg/day, licensed dosage) and sapropterin (20 mg/kg/day, maximum licensed dosage) for 4 weeks each, with a 14-day washout between treatments. The primary endpoint was mean change in blood Phe from baseline to Weeks 3–..