First-in-Human, Multiple Part Clinical Study of JNT-517 in Healthy Participants and in Participants With Phenylketonuria

Key Inclusion Criteria:

Parts A, B, C, and F:

• Males and females 18 to 55 years of age.
• Medically healthy with no clinically significant medical history.
• Body mass index (BMI) of 18-40 kg/m2 and total body weight >50 kg (110 lbs).
• Non-smoker for at least 2 weeks prior to dosing and willing to abstain during the study.

Part D and E:

• Males and females 18 to 65 years of age, inclusive.
• Diagnosis of PKU with a confirmed genotype.
• At least 2 plasma Phe levels >600 μM over the past 12 months.
• BMI of 18-40 kg/m2.

All Parts:

• Females of childbearing potential must agree to use 2 highly effective contraceptive methods.
• Capable of giving signed informed consent and able to comply with study procedures.

Key Exclusion Criteria:

All Parts:

• Any acute or chronic medical condition that would prevent the participant from complying with the procedures or place the participant at risk if they participate in the study.
• Positive for hepatitis B or C or human immunodeficiency virus.
• Any history of malignancy in the last 5 years, excluding non-melanoma skin cancer.
• Any history of liver disease.
• Any surgical or medical conditions that may affect study drug absorption, distribution, metabolism, or excretion.
• Participation in another investigational drug trial within 30 days or, if known, 5 half-lives of the investigational drug (whichever is longer).
• History of drug/alcohol abuse in the last year.
• Current, recent, or suspected infection within 4 weeks of Screening of SARS-CoV-2/COVID-19.
• Received a vaccine for SARS-CoV-2/COVID-19 within 14 days of Screening.
• Unable to tolerate oral medication.
• Allergy to JNT-517 or any component of the investigational product.
• Received >50 mL of blood or plasma within 30 days of Screening or >500 mL of blood or plasma within 60 days of Screening.