This study tests a new drug, RGLS8429, for people with Autosomal Dominant Polycystic Kidney Disease (ADPKD), a condition causing kidney cysts to grow. The study has two parts and tests different doses. The drug is given by injection under the skin, and researchers want to know if it is safe, how it works in the body, and how it affects kidneys. ADPKD patients aged 18-70 can join. Some cannot join, like those who recently used certain medicines or have alcohol/drug problems. If you join, you'll be in a double-blind test, meaning neither you nor the researchers know if you are getting the real drug or a placebo (a fake version). This helps make sure results are fair.

• Study consists of two parts with different doses and involves injections.
• Participants must be between 18-70 years old and meet specific health criteria.
• Participants cannot have used certain drugs or have a history of substance abuse.