Study of Efficacy and Safety of Tonlamarsen in Participants With Acute Severe Hypertension Recently Discharged From the Hospital

Key Inclusion Criteria: * Age 18 or older, body weight ≥ 50 kg * Recently discharged from the hospital to home within the past 3 days during which evaluation and/or treatment of acute severe hypertension (documented systolic blood pressure \>180 mmHg and/or diastolic \>110 mmHg) occurred, as measured by a healthcare provider within the 24 hours preceding hospitalization or during the initial 24 hours of hospitalization * At Screening and Randomization visit, average systolic blood pressure \> 145 mmHg * Presence of established cardiovascular or renal comorbidities Key Exclusion Criteria: * Has known history of secondary hypertension * Any malignancy requiring treatment within 5 years * Has abnormal thyroid function with clinical significance * Recent hospitalization for stroke, type 1 myocardial infarction or coronary revascularization within 3 months prior to the first on-study visit * History of and/or obvious clinical signs or symptoms of cirrhosis or other significant liver disease * Alanine aminotransferase or aspartate aminotransferase \>2 x upper limit of normal * Most recent hospitalization was for non-cardiovascular or non-renal conditions