Add-On Treatment With Zilebesiran for Inadequately Controlled Hypertension

Importance In prior monotherapy studies of patients with hypertension, single subcutaneous doses of zilebesiran, an investigational RNA interference therapeutic, reduced serum angiotensinogen levels and systolic blood pressure (SBP) at 3 and 6 months. Objective To evaluate the efficacy and safety of zilebesiran vs placebo when added to a standard antihypertensive medication. Design, Setting, and Participants This phase 2, randomized, prospective, double-blinded trial enrolled adults with uncontrolled hypertension from 150 sites across 8 countries between January 2022 and June 2023. The final follow-up date was December 11, 2023, and analyses were conducted on March 1, 2024. Interventions Eligible patients were initially randomized in cohorts to receive open-label run-in treatment for at least 4 weeks with indapamide 2.5 mg, amlodipine 5 mg, or olmesartan 40 mg (4:7:10 randomization), each administered once daily. Within cohorts, adherent patients with 24-hour mean ambulatory SBP of 130 mm Hg to 160 mm Hg were subsequently randomized (1:1) to additional blinded treatment to receive single subcutaneous doses of zilebesiran 600 mg or matching placebo. Main Outcomes and Measures The primary end point in each cohort was the difference between zilebesiran and placebo in change from baseline in 24-hour mean ambulatory SBP at 3 months. Results Of 1491 patients entering the run-in phase, 663 (130 receiving indapamide, 240 receiving amlodipine, and 293 receiving olmesartan) were randomized to receive zilebesiran (n = 332) or placebo (n = 331). The least-squares mean difference between zilebesiran and placebo in change from baseline to 3 months in 24-hour mean ambulatory SBP was −12.1 mm Hg (95% CI, −16.5 to −7.6; P  < .001) for indapamide, −9.7 mm Hg (95% CI, −12.9 to −6.6; P  < .001) for amlodipine, and −4.5 mm Hg (95% CI, −8.2 to −0.8; P  = .02) for olmesartan. Across cohorts, more patients who received zilebesiran than placebo experienced hyperkalemia (18 [5.5%] vs 6 [1.8%]), hypotension (14 [4.3%] vs 7 [2.1%]), and acute kidney failure (16 [4.9%] vs 5 [1.5%]) events, but most episodes were mild and resolved without medical intervention. Conclusions and Relevance In patients with uncontrolled hypertension despite treatment with indapamide, amlodipine, or olmesartan, the addition of single-dose zilebesiran resulted in significant SBP reductions compared with placebo at 3 months, with low rates of serious adverse events. Trial Registration ClinicalTrials.gov Identifier: NCT05103332