A Study of RGLS8429 in Patients With Autosomal Dominant Polycystic Kidney Disease

Key Inclusion Criteria: 1. Male or female ADPKD patients, 18 to 70 years old 2. Class 1C, 1D, or 1E Mayo Imaging Classification of ADPKD (based upon either the MRI obtained during screening, or a prior MRI obtained within 5 years of screening with documented Mayo classification) 3. eGFR between 30 to 90 mL/min/1.73 m2 4. Body mass index (BMI) 18 to 35 kg/m2 5. Must understand and consent to the study procedures explained in the ICF and be willing and able to comply with the protocol Key Exclusion Criteria: 1. Administration of tolvaptan in the 28 days before randomization 2. Subject is mentally incapacitated or has significant emotional problems 3. Any medical condition or social circumstance that, in the opinion of the Investigator, may make the subject unlikely to complete the study or comply with study procedures and requirements; or may pose a risk to the subject's safety 4. History or presence of alcoholism or drug abuse within the past 2 years prior to screening 5. Only one kidney or kidney transplant recipient 6. Participation in another clinical trial and/or exposure to any investigational drug or approved therapy for investigational use within 28 days or 5 half-lives of the investigational drug's dosing, whichever is longer, prior to dosing. The 28-day or 5-half-life windows will be calculated from the date of the last dosing in the previous study to Day 1 of the current study.