After earlier clinical studies showed promising reductions in blood phenylalanine, the program advanced into a global Phase 3 study in adults with PKU.
What Is Repinatrabit?
Repinatrabit, originally known by the development code JNT-517, is an investigational oral small-molecule treatment being studied for people with PKU.
Unlike therapies that replace or enhance phenylalanine hydroxylase activity, repinatrabit is designed to work through a different pathway.
The treatment inhibits SLC6A19, a protein involved in the reabsorption of neutral amino acids in the kidney. By reducing the amount of phenylalanine reabsorbed back into the bloodstream, researchers are studying whether more phenylalanine can instead be removed through the urine and blood phenylalanine levels can be lowered.
Repinatrabit is being studied as a different strategy: increasing the removal of phenylalanine through the kidneys.
Because it is an oral small molecule and acts through a pathway outside the defective PAH enzyme itself, researchers are interested in whether it may eventually provide another treatment option for a broad range of people with PKU.
From Early Research to Phase 3
The repinatrabit program began with a first-in-human Phase 1/2 study evaluating safety, tolerability, pharmacokinetics and early treatment effects in healthy volunteers and adults with PKU.
Results from the earlier program showed reductions in blood phenylalanine in adults with PKU and supported further development of the treatment.
Otsuka initiated the global Phase 3 program in late 2025. The current pivotal study, JNT517-301, is evaluating the safety and efficacy of repinatrabit in adults with PKU.
The sponsor plans to enroll approximately 120 participants internationally. The study compares repinatrabit with placebo during an initial blinded treatment period before participants move into a longer period of active treatment.
Recruitment status, eligibility requirements, participating locations and timelines can change. Anyone considering participation should use the official study sources below for current information.
That has now changed. ClinicalTrials.gov currently lists M.A.G.I.C. Clinic in Calgary, Alberta as a recruiting Canadian study site, with Dr. Aneal Khan listed as principal investigator.
Health Canada's Canadian Clinical Trial Search Portal also now contains the JNT517-301 study record.
The Research Program Is Broader Than One Study
Repinatrabit is being evaluated through several related clinical studies.
The original JNT517-101 Phase 1/2 study has been completed. A Phase 2 study in adolescents, JNT517-201, has also been completed.
A separate long-term study, JNT517-501, is evaluating longer-term safety and efficacy in both pediatric and adult participants. Current sponsor information lists that study as recruiting.
It is still investigational, so the Phase 3 program is important for determining how effectively and safely the treatment lowers phenylalanine over a longer period and across a larger group of participants.
For Canadian adults interested in research participation, the presence of a Calgary site means there is currently an opportunity to explore participation without necessarily travelling outside Canada.
Finding a study does not mean that someone will qualify. Final eligibility is determined by the study team.
At the time, CanPKU+ had independently confirmed recruitment at M.A.G.I.C. Clinic even though the Calgary location was not yet visible in ClinicalTrials.gov.
The official registry has since been updated to include the Calgary site. Moving this information into a dated Research Article allows us to preserve that research history while directing people to official sources for information that will continue to change.
Learn More and Check Current Study Information
Recruitment status and study details can change. Use these sources for the latest information.
View JNT517-301 on ClinicalTrials.gov Current recruitment, eligibility and study locations View the Otsuka JNT517-301 Study Page Study information maintained by the sponsor View the Health Canada Trial Record Canadian Clinical Trial Search Portal M.A.G.I.C. Clinic Clinical Trials Current Calgary research opportunitiesAbout this article: CanPKU+ provides plain-language research information to help our community understand emerging therapies and research relevant to PKU.
