Study of YOLT-203 in Children and Adults With Primary Hyperoxaluria Type 1 (PH1)

A Randomized, Double-blind, Placebo-controlled Study Followed by a Treatment Extension to Evaluate the Efficacy and Safety of YOLT-203 in Children and Adults With Primary Hyperoxaluria Type 1

This study will be conducted to evaluate the efficacy and safety of YOLT-203 in children and adults with Primary Hyperoxaluria Type 1.

After the initial randomized, 6-month double-blind, placebo-controlled period, participants who were initially assigned to placebo will receive a single-dose of YOLT-203 treatment whereas participants in the YOLT-203 group will receive a single-dose of placebo infusion.

For patients interested in additional information on how to participate, please follow this link: https://mytomorro.ws/ph1trial.

Inclusion Criteria

• You are 6 years old or older.
• You have been diagnosed with PH1 (primary hyperoxaluria type 1) through genetic testing.
• Urine tests show that your oxalate levels are not within certain limits (based on at least two 24-hour urine collections).
• If you take vitamin B6, your dose has been stable for at least 3 months, and you are willing to keep it the same during the study.
• You (and/or your parent or legal guardian, if you are under 18) understand the study and agree to follow all study requirements, including signing a consent form.

Exclusion Criteria

• You have signs that oxalate has affected parts of your body outside the kidneys.
• Your liver blood tests are not within certain limits.
• You have certain abnormal blood clotting results (unless controlled with medication like warfarin).
• You have HIV, or active or chronic hepatitis C.
• You are pregnant, planning to become pregnant, or breastfeeding.
• You are not willing to use birth control during the study and for 6 months after (if applicable).
• You are unable to limit alcohol intake to no more than about 2 drinks per day.
• You have had alcohol or drug abuse in the past year.
• You are unable to follow standard treatments for PH1 (such as drinking plenty of fluids, taking prescribed medications like potassium citrate, or following dietary advice).