A Study to Evaluate DCR-PHXC in Children and Adults With Primary Hyperoxaluria Type 1 and Primary Hyperoxaluria Type 2

Key Inclusion Criteria: * Capable and willing to provide written informed consent or assent * Documented diagnosis of PH1 or PH2, confirmed by genotyping * Must meet the 24 hour urine oxalate excretion requirements * Less than 20% variation between the two 24-hour urinary creatinine excretion values derived from the two 24-hour urine collections in the screening period * Estimated GFR at screening ≥ 30 mL/min normalized to 1.73 m2 BSA Key Exclusion Criteria: * Renal or hepatic transplantation (prior or planned within the study period) * Currently on dialysis or anticipated requirement for dialysis during the study period * Plasma oxalate \>30 µmol/L * Documented evidence of clinical manifestations of systemic oxalosis (including pre-existing retinal, heart, or skin calcifications, or history of severe bone pain, pathological fractures, or bone deformations) * Use of an RNA interference (RNAi) drug within the last 6 months * Participation in any clinical study in which you received an investigational medicinal product (IMP) within 4 months before Screening * Liver function test (LFT) abnormalities: Alanine aminotransferase (ALT) and/or aspartate aminotransferase (AST) \>1.5 times upper limit of normal (ULN) for age and gender * Inability or unwillingness to comply with study procedures