Testing JNT-517 against a placebo for phenylketonuria

Exclusion

• −Allergy to JNT-517 or any component of the investigational product
• −Positive for hepatitis B or C or human immunodeficiency virus
• −Exclusion CriteriaExclusion criteriaThe things that would prevent someone from taking part.Read more →
• −Participants will be excluded from the study if any of the following criteria are met:
• −Any acute or uncontrolled 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
• −Any history of malignancy of any organ system (other than non-melanoma skin cancer or in situ cervical cancer), treated or untreated, within the past 5 years, regardless of whether there is evidence of local recurrence or metastases
• −Any history of significant liver disease
• −Any history of cataracts or more than minimal cataracts observed during the ScreeningScreeningThe checks done before joining, to see whether a study fits.Read more → ophthalmologic examination. Minimal cataracts are defined as changes similar to lens opacities classification system III (LOCS III), lens grade C1, N1 or P1
• −Any surgical or medical conditions that may affect study drug absorption, distribution, metabolism, or excretion
• −Estimated glomerular filtration rate (eGFR) \<60 mL/min/1.73 m2 by 2021 Chronic Kidney Disease Epidemiology Collaboration formula
• −Participation in another investigational drug trial within 30 days or, if known, 5 half-lives of the investigational drug (whichever is longer). For gene therapy or editing trials, participants must have received the intervention \>6 months prior to Screening visit and with stable plasma Phe in the past 2 months prior to Screening visit.
• −Alcohol consumption within 5 days of randomizationRandomisedWhich group you go into is decided by chance, not by you or your doctor.Read more → and/or unwilling to limit to 1 alcoholic drink per day until after the 6-month study visit
• −History of drug/alcohol abuse in the last year
• −Use of any medications that are inhibitors or inducers of cytochrome P450 (CYP3A4) or inhibitors of the transporter P-glycoprotein (P-gp) within 4 weeks prior to randomization and unwilling and/or unable to avoid these medications throughout the treatment duration
• −Current, recent, or suspected active viral or bacterial infection within 2 weeks prior to and during the Screening Period
• −Unable to tolerate oral medication or have a condition that would interfere with the absorption of JNT-517
• −Any of the following laboratory values at the Screening visit: -Alanine aminotransferase or aspartate aminotransferase values \>1.5× the upper limit of normal (ULN)-Total bilirubin ˃ULN unless history of Gilbert Syndrome and then total bilirubin \>4 milligrams per deciliter (mg/dL) is exclusionary-Hemoglobin \<11.0 grams per deciliter (g/dL) \[\<110.0 grams per liter (g/L)\]-White blood cell count \>ULN-Platelets \<150 × 10\^9/Liter (L) (\<150,000/cubic millimeters \[mm\^3\]).
• −Use of any medications that are substrates of breast cancer resistance protein (BCRP), multidrug and toxin extrusion (MATE)1, or MATE2-K within 4 weeks prior to randomization and unwilling and/or unable to avoid these medications throughout the treatment duration NOTE: Participants will be permitted to continue with estrogen- or progesterone-based oral contraceptives, but must agree to use 2 other methods of contraception, where at least 1 must be highly effective, or must agree to sexual abstinence during the study.