Efficacy and Safety of SYNB1934 in Patients With PKU (SYNPHENY-3)

• Status: Not yet recruiting
• Trial end date: 2027-10-15
• Target enrollment: 0
• Participant gender: All

Summary

This is a 3-part, Phase 3 study consisting of a dose-escalating period (DEP) of up to 15 weeks (Part 1), followed by a 4-week, double-blind, placebo-controlled randomized withdrawal period (RWP) (Part 2), and an open-label extension (OLE) (Part 3) of up to 36 months.

• Phase: Phase 3
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: Synlogic

Criteria

Inclusion Criteria:

• Age ≥ 18 years

• Able and willing to voluntarily complete the informed consent process.

• Diagnosis of phenylketonuria (PKU) and failure to maintain recommended blood Phe levels on existing management (sapropterin, sepiapterin and/or Phe-restricted diet), demonstrated by 2 blood Phe concentration measurements > 360 μmol/L, at least 7 days apart, during the screening period; or a single value during screening and history of blood Phe concentration >360 μmol/L on current treatment, as determined by central or local laboratory.

• Females of childbearing potential must have a negative pregnancy test at screening and the end of DEP (in order to enter the RWP) and RWP (in order to enter the OLE) and be willing to have additional pregnancy tests during the study.

• Sexually active female patients of childbearing potential must be willing to use an acceptable method of contraception while participating in the study and for 2 weeks after the last dose.

• Stable diet including stable medical formula regimen (if used) for at least 1 month prior to screening.

• If using sapropterin or sepiapterin, must be on a stable dose for at least 3 months.

• Willing and able to continue current diet, medication and to engage in all study activities.

Exclusion Criteria:

• Currently taking Palynziq® (pegvaliase-pqpz) (within 1 month of screening).

• Acute or chronic medical, surgical, psychiatric, or social condition or laboratory abnormality that may increase patient risk associated with study participation, compromise adherence to study procedures and requirements, and, in the judgment of the investigator, would make the patient inappropriate for enrollment.

• Diagnosis of irritable bowel syndrome.

• Intolerance to or allergic reaction to E. coli Nissle or any of the ingredients in SYNB1934 formulation, or an allergy to cinnamon. Known intolerance to proton pump inhibitors and H2 blockers.

• Currently taking or plans to take any type of systemic (e.g., oral or intravenous) antibiotic within 28 days prior to the first dose of SYNB1934 through final safety assessment in RWP, including planned surgery, hospitalizations, dental procedures, or interventional studies that are expected to require antibiotics. Exception: topical antibiotics are allowed.

• Pregnant, planning to become pregnant, or breastfeeding.

• Current participation in any other investigational drug study or use of any investigational agent within 30 days or 5 half-lives (whichever is longer) prior to screening.

• Ever received gene therapy for treatment of PKU.