A Phase 1/Phase 2 Open-label Study to Evaluate the Safety, Tolerability, and Efficacy of a Single Intravenous Administration of SAR444836 in Adult Participants With Phenylketonuria

Inclusion Criteria:

• Adult males, and females of non-childbearing potential, 18-65 years of age at thetime of informed consent.

• Participants must have uncontrolled classical PKU due to PAH deficiency (despitePhe-restricted dietary management or Palynziq) in the judgement of the Investigator.

• Two historical plasma Phe values ≥ 600 μmol/L in the preceding 12 months while onPhe restricted diet therapy. Two plasma Phe values ≥ 600 μmol/L drawn at least 72hours apart during the screening period while on Phe restricted diet therapy in theabsence of an acute illness.

• Participant has the ability and willingness to maintain their present diet for theduration of the Post-treatment Follow-up Phase (through Week 96), unless otherwisedirected as per protocol

• Body mass index (BMI) ≤ 35 kg/m2

• Willingness to use effective methods of contraception.

• Capable of giving signed informed consent which includes compliance with therequirements and restrictions listed in the informed consent form (ICF) and in thisprotocol.

Exclusion Criteria:

• Presence of neutralizing antibodies against the AAV SNY001 capsid

• Abnormal liver function laboratory testing evidenced by alanine aminotransferase (ALT)>1.5X upper limit normal (ULN), aspartate transaminase (AST)>1.5X ULN, alkalinephosphatase >1.5X ULN, Total and direct bilirubin >1.5X ULN (bilirubin levels abovethe laboratory's normal range are acceptable in individuals with a documentedhistory or laboratory evidence of Gilbert's Disease)

• Any significant underlying liver disease or any of the following documenteddiagnoses, indicative of significant underlying liver disease:

• Portal hypertension; or

• Splenomegaly; or

• Hepatic encephalopathy

• Serum albumin measurement below the lower limit of normal of the laboratory ORAST-to-Platelet Ratio Index > 1.0

• Serum creatinine >1.5X ULN

• Hemoglobin A1c >6.5% or fasting glucose >126 mg/dL

• Screening laboratory testing demonstrating any of the following:

• HIV; or

• active or prior hepatitis B virus (HBV) infection defined as positive test forhepatitis B surface antigen (HBsAg) or positive test for hepatitis B coreantibody (total HBcAb) or detectable HBV DNA; or

• active hepatitis C virus (HCV) infection defined as positive test for hepatitisC antibody followed by detectable HCV RNA or if a participant is presentlyreceiving (or has received within 6 months prior to screening) anti-viraltherapy for hepatitis C

• Clinically significant, active bacterial, viral, fungal, or parasitic infection (based on Investigator's judgement)

The above information is not intended to contain all considerations relevant to a potential participation in a clinical trial.