RecruitingGenetic interventionAAV Gene Therapy Clinical Study in Adult Classic PKU (PHEdom)This is a Phase 1/2, open-label, multiple-center, dose escalation and cohort expansion study to evaluate the safety and efficacy of NGGT002 in adult subjects with classic Phenylketonuria (PKU). NGGT002 is an rAAV8 based vector carrying a functional copy of the human PAH gene. Participants will receive a single administration of NGGT002 and will be followed for safety and efficacy for 5 years.