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Other names | AD-85481, ALN-85481, ALN-AGT01 |
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Formula | C89H152N16NaO36P |
Molar mass | 2076.235 g·mol−1 |
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Zilebesiran (development code ALN-AGT01) is an investigational RNA interference (RNAi) therapeutic agent being developed by Roche and Alnylam Pharmaceuticals for the treatment of hypertension. [1] [2]
It is small interfering RNA that is administered subcutaneously twice annually to lower blood pressure in people already taking other antihypertensive drugs. [3] [4] [5] The drug is designed to inhibit hepatic angiotensinogen synthesis through targeted silencing of the angiotensinogen gene, offering the potential for prolonged blood pressure control with infrequent dosing. [1] [6] [7]
Zilebesiran works by targeting the hepatic production of angiotensinogen, which is the sole precursor of angiotensin peptides and plays a key role in the pathogenesis of hypertension. [1] The drug utilizes small interfering RNA (siRNA) technology to post-transcriptionally silence the angiotensinogen (AGT) gene in liver cells. [8]
The mechanism involves several steps: zilebesiran, conjugated with GalNAc (N-acetylgalactosamine), binds to the asialoglycoprotein receptor (ASGPR) on hepatocytes, enters endosomes, and releases the siRNA component which then binds to the RNA-induced silencing complex (RISC). [9] The siRNA guide strand hybridizes with AGT mRNA, leading to its degradation and ultimately reducing angiotensinogen protein synthesis. [9]
Clinical studies have shown that zilebesiran reduces serum angiotensinogen levels by more than 90%, leading to downstream reductions in the vasoconstrictor angiotensin II. [2] This approach targets the renin-angiotensin-aldosterone system at its most upstream point, potentially offering more comprehensive blockade than traditional ACE inhibitors or ARBs. [10]
The first-in-human Phase 1 study of zilebesiran was a randomized, double-blind, placebo-controlled trial conducted in 107 patients with mild-to-moderate hypertension. [1] Results published in the New England Journal of Medicine in July 2023 demonstrated that single subcutaneous doses of zilebesiran led to dose-dependent decreases in both serum angiotensinogen levels and 24-hour ambulatory blood pressure that were maintained for up to 24 weeks. [1]
The study showed that doses of 200 mg or higher achieved sustained blood pressure reductions, with the 800 mg dose producing mean reductions in 24-hour systolic blood pressure of greater than 20 mmHg at six months. [11] Patients experienced consistent and sustained lowering of both daytime and nighttime systolic blood pressure throughout the six-month observation period. [11]
The KARDIA-1 Phase 2 trial was a randomized, double-blind, placebo-controlled, multicenter global dose-ranging study designed to evaluate the efficacy and safety of zilebesiran as monotherapy in adults with mild-to-moderate hypertension. [12] The study enrolled 394 adults representing a diverse population and evaluated multiple dose levels of zilebesiran compared to placebo. [12] [13]
The KARDIA-2 study evaluated zilebesiran as an add-on therapy to standard of care antihypertensive medications. [10] Results announced in March 2024 demonstrated clinically significant blood pressure reductions when zilebesiran was added to existing antihypertensive regimens. [10] [14]
The KARDIA-3 Phase 2 study is a randomized, double-blind, placebo-controlled, multicenter study designed to evaluate the efficacy and safety of zilebesiran used as an add-on therapy in adult patients with high cardiovascular risk. [15] [10] [16] Enrollment was completed in 2025, with the study evaluating zilebesiran in combination with at least two antihypertensives in patients with uncontrolled hypertension. [16]
In September 2025, Roche and Alnylam advanced zilebesiran into a global phase III cardiovascular outcomes trial for people with uncontrolled hypertension. [17]
Clinical trials have demonstrated that zilebesiran provides dose-dependent and sustained blood pressure reductions lasting up to 24 weeks after a single subcutaneous injection. [1] The KARDIA clinical program has enrolled more than 600 patients across Phase 2 trials, demonstrating clinically significant blood pressure reductions with encouraging safety profiles both as monotherapy and as add-on therapy. [18]
The drug achieves tonic blood pressure control with consistent and durable blood pressure reduction throughout a 24-hour period, sustained for months after a single dose. [19] This prolonged duration of action represents a potential paradigm shift in hypertension management, offering the possibility of infrequent dosing schedules compared to daily oral medications. [20]
Clinical trials have reported that zilebesiran has a satisfactory safety profile and is well tolerated by patients. [2] The most commonly observed adverse events were mild injection-site reactions at the subcutaneous injection site. [1] No serious adverse events directly attributable to zilebesiran have been reported in published studies. [1]
The safety profile appears favorable across the dose ranges studied, with higher doses showing proportionally greater efficacy without significant increases in adverse events. [18] The infrequent dosing schedule may also contribute to improved patient tolerability and adherence compared to daily oral antihypertensive medications. [20]
Zilebesiran utilizes Alnylam's Enhanced Stabilization Chemistry Plus (ESC+) GalNAc-conjugate technology, which enables targeted delivery to liver cells and enhanced stability of the siRNA molecule. [10] The GalNAc conjugation allows for specific uptake by hepatocytes through the asialoglycoprotein receptor, ensuring targeted delivery to the site of angiotensinogen synthesis. [9]
This technology platform represents an advancement in RNAi therapeutics, providing prolonged duration of action that distinguishes zilebesiran from traditional small molecule drugs targeting the renin-angiotensin-aldosterone system. [21]
As of September 2025, zilebesiran remains an investigational drug that has not received approval from regulatory agencies. [16] The compound has completed through Phase 2 clinical development as part of the KARDIA clinical program, with plans for Phase 3 studies based on the positive results from earlier trials. [16]