Safety and Efficacy Study of NGGT002 in PKU Adult Subjects

Inclusion Criteria: * Voluntarily sign informed consent form; * Male and female subjects with diagnosis of PKU caused by confirmed phenylalanine hydroxylase(PAH) mutation according to the "Clinical Practice Guidelines for Phenylketonuria, 2020 Edition"; * Age ≥ 18 years; * Blood phenylalanine (Phe) concentration ≥ 600 μmol/L at least once within 2 years prior to screening, with one measurement confirmed within six months of enrollment; * Subjects are able to maintain their baseline diet throughout the study (regardless of dietary phenylalanine restriction), and willingness to follow the instruction of investigators to manage the diet for the duration of the trial; * Subjects are required to obtain approval from the investigator prior to the use of any concomitant medications during the study period; * Willingness and capable per Investigator opinion to comply with study procedures and requirements; * Female participants of childbearing potential must have abstained from unprotected sexual intercourse for at least 14 days prior to dosing, and must have a documented negative serum hCG test between Day -7 and Day 0. All participants must be willing to use a highly effective method of contraception for at least 12 months following NGGT002. Exclusion Criteria: * Anti-AAV8 neutralizing antibody\>1:10 * Prior gene therapy * Positive hepatitis B virus surface antigen, hepatitis C virus antibody, anti-human immunodeficiency virus antibody or treponema pallidum-specific antibody * H…