Is subcutaneous zilebesiran available for enrollment in a clinical trial for patients with resistant hypertension despite at least two oral antihypertensive agents, one of which must be a diuretic?

Zilebesiran is currently investigational and available only through clinical trial enrollment for resistant hypertension

Yes, subcutaneous zilebesiran is available for enrollment in clinical trials for patients with resistant hypertension, including those on at least two oral antihypertensives with a diuretic. The drug is not yet FDA-approved for routine clinical use but is being actively studied in the KARDIA trial program 1.

Current Clinical Trial Status

Zilebesiran is an RNA interference therapeutic that inhibits hepatic angiotensinogen synthesis, providing sustained blood pressure reduction for approximately 6 months after a single subcutaneous injection 1. The 2024 ESC Guidelines specifically mention this agent as an investigational therapy that has shown promise in phase 2 trials, with a single dose reducing 24-hour blood pressure over approximately 6 months 1.

KARDIA Trial Program

The most relevant trial for your patient population is KARDIA-2, which specifically evaluated zilebesiran as add-on therapy in patients with uncontrolled hypertension despite standard treatment 2:

• Study Design: Patients received run-in treatment with indapamide 2.5 mg, amlodipine 5 mg, or olmesartan 40 mg for at least 4 weeks
• Eligibility: 24-hour mean ambulatory systolic BP 130-160 mmHg despite treatment
• Intervention: Single subcutaneous dose of zilebesiran 600 mg vs placebo
• Results at 3 months:
  • With indapamide: -12.1 mmHg reduction (95% CI, -16.5 to -7.6; P < .001)
  • With amlodipine: -9.7 mmHg reduction (95% CI, -12.9 to -6.6; P < .001)
  • With olmesartan: -4.5 mmHg reduction (95% CI, -8.2 to -0.8; P = .02)

KARDIA-3 is currently enrolling to evaluate cardiovascular outcomes in a larger global population 3.

Safety Profile from Clinical Trials

The safety data from completed trials shows 2, 4:

Common adverse events (generally mild and self-resolving):

• Hyperkalemia: 5.5% vs 1.8% placebo
• Hypotension: 4.3% vs 2.1% placebo
• Acute kidney injury: 4.9% vs 1.5% placebo
• Injection site reactions: most common drug-related event

Important caveat: Most episodes were mild and resolved without medical intervention. No serious hypotension or renal impairment requiring intervention was observed in short-term studies 5, 6.

Patient Selection Considerations

Your patient would be appropriate for trial enrollment if they meet these criteria:

Inclusion factors:

• Uncontrolled BP despite ≥2 antihypertensive agents (including a diuretic)
• 24-hour ambulatory systolic BP 130-160 mmHg
• Adherent to current medication regimen

Relative contraindications based on trial exclusions:

• Serum potassium >4.5 mmol/L (increased hyperkalemia risk)
• eGFR <45 mL/min/1.73m² (increased renal adverse events)
• Pregnancy or planning pregnancy (long duration of action is problematic)
• Volume depletion states (theoretical concern with prolonged RAAS suppression) 7

Current Standard of Care While Awaiting Trial Enrollment

The 2024 ESC Guidelines provide clear recommendations for resistant hypertension management that should be implemented first 1:

Step 1: Reinforce lifestyle measures, especially sodium restriction <2.4 g/day

Step 2: Add low-dose spironolactone (25 mg daily) as the preferred fourth-line agent

Step 3: If spironolactone not tolerated or contraindicated:

• Eplerenone (alternative MRA)
• Amiloride (potassium-sparing diuretic)
• Higher-dose thiazide-like diuretic (chlorthalidone preferred over hydrochlorothiazide) 8
• Loop diuretic if eGFR <30 mL/min/1.73m²
• Bisoprolol or doxazosin

Step 4: Consider renal denervation at medium-to-high volume centers after shared decision-making 1

How to Access Clinical Trials

To enroll your patient:

1. Search ClinicalTrials.gov for "zilebesiran" and "KARDIA" to identify active sites
2. Contact trial coordinators at participating centers (150 sites across 8 countries were involved in KARDIA-2) 2
3. Ensure proper documentation of resistant hypertension with 24-hour ambulatory BP monitoring (required for trial entry)
4. Exclude pseudoresistance before referral: white coat effect, medication nonadherence, suboptimal drug regimen 9

Critical Limitations to Discuss

The modest BP reduction in KARDIA-1 (10-15 mmHg) means zilebesiran will likely require combination therapy rather than monotherapy 7, 4. This somewhat limits its advantage for adherence compared to optimized conventional therapy.

The long duration of action (6 months) is both an advantage and a risk: during volume depletion, sepsis, or unexpected pregnancy, you cannot simply discontinue the drug 7. This requires careful patient selection and counseling.

High sodium intake attenuates efficacy based on Part B of the phase 1 trial 5, so lifestyle modification remains essential even with this novel therapy.