A Study to Evaluate the Efficacy and Safety of Mitapivat in Pediatric Participants With Pyruvate Kinase Deficiency (PKD) Who Are Regularly Transfused, Followed by a 5-Year Extension Period

ACTIVATE-KidsT (AG348-C-022) is a multicenter study designed to evaluate the efficacy and safety of treatment with mitapivat compared with placebo in pediatric participants with pyruvate kinase deficiency (PK deficiency) who are regularly receiving blood transfusions. Participants will be randomized 2:1 to receive either mitapivat or matching placebo. Randomization will be stratified by age (1 to \< 6 years, 6 to \< 12 years, 12 to \< 18 years) and splenectomy status. Participants will be dosed by age and weight during a double-blind period consisting of an 8-week dose titration period followed by a 24-week fixed-dose period. Participants who complete the double-blind period will be eligible to receive mitapivat for up to 5 years in the open-label extension (OLE) period.