A Study to Evaluate ALN-AGT01 RVR in Adult Patients With Mild to Moderate Hypertension Pretreated With Zilebesiran

Part A: Inclusion Criteria * Is an adult participant with a mean seated office systolic blood pressure (SBP) of at least 130 mmHg and no more than than 170 mmHg * Either not taking antihypertensive medication or on stable therapy with up to 2 antihypertensive medications Part B: Inclusion Criteria * Is an adult participant with a mean seated office SBP of at least 140 mmHg and no more than 170 mmHg * Has discontinued all prior antihypertensive medication other than a calcium channel blocker (CCB) and/or thiazide/thiazide-like diuretic (if taking) for at least 3 weeks Both Parts: Exclusion Criteria * Has known secondary hypertension or serum potassium more than 5 mmol/L * Has an estimated glomerular filtration rate (eGFR) less than 30 mL/min/1.73m\^2 Note: other protocol defined inclusion / exclusion criteria apply