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Taking people in CanadaPhase 3

Tests zilebesiran in adults with high-risk heart disease and high blood pressure

Tests zilebesiran against placebo in adults with uncontrolled high blood pressure and heart risk.

Key facts

Who runs it
Alnylam Pharmaceuticals
Where
Brampton, Burlington, Cambridge, Chicoutimi, Edmonton, Etobicoke, Greater Sudbury, Laval, Lévis, London, Longueuil, Mirabel, Mississauga, Moncton, Montreal, Peterborough, Québec, Richmond, Rimouski, Saint-Jérôme, Sarnia, Scarborough, Sherbrooke, Sydney, Toronto, Trois-Rivières, and Windsor, CanadaSee the 27 sitesAlso in 34 other countries, 824 sites
Registry title
Zilebesiran in Patients With Hypertension Not Adequately Controlled and With Either Established Cardiovascular Disease or High Risk for Cardiovascular Disease
Status
Recruiting
Phase
Phase 3
People taking part
11,000 people, planned
Started
6 Sept 2025
Expected to end
23 Sept 2030
Type of study
Interventional, 2 groupsOne group gets a placebo (a dummy treatment), for comparison.
Treatments tested
  • Zilebesiran
  • Placebo
Record updated
12 November 2026

Who can take part

AI summary

From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.

The trial is looking for adults whose high blood pressure is not well controlled despite treatment, and who either have heart or blood vessel disease or are at high risk for it.

Age
18 years or older if you already have cardiovascular disease; 55 years or older if you are at high risk for it.
Sex
All sexes can join.
Disease stage
Treated high blood pressure that is not adequately controlled, with established cardiovascular disease (coronary, cerebrovascular or peripheral artery disease) or a high risk for cardiovascular disease.
Earlier treatment
Must be on stable treatment with at least 2 standard blood pressure medicines, and one of them must be a thiazide, thiazide-like or loop diuretic.

Main reasons for not taking part

  • Known history of secondary hypertension
  • Symptomatic orthostatic hypotension
  • Liver tests ALT or AST above 3 times the upper limit of normal
  • Total serum bilirubin above 1.5 times the upper limit of normal
  • Serum potassium above 4.8 mEq/L or eGFR below 30 mL/min/1.73m^2

The registry criteria, word for word

Show all 11 criteriaShow less

Who can take part

  • Is 18 years or older for patients with established cardiovascular disease (CVD)
  • Is 55 years or older for patients with high risk for CVD
  • Has established CVD (defined as coronary, cerebrovascular, or peripheral artery disease) or high risk for CVD
  • Has treated hypertension on stable therapy with at least 2 standard of care antihypertensive medications, one of which must be a thiazide, thiazide-like, or loop diuretic

Who cannot take part

  • Has known history of secondary hypertension
  • Has alanine aminotransferase (ALT) or aspartate aminotransferase (AST) >3×upper limit of normal (ULN)
  • Has total serum bilirubin >1.5×ULN
  • Has international normalized ratio (INR) >1.5
  • Has serum potassium >4.8 mEq/L
  • Has estimated glomerular filtration rate (eGFR) <30 mL/min/1.73m\^2
  • Has symptomatic orthostatic hypotension

Where in Canada

Also in 34 other countries, 824 sites

  • Brampton, OntarioHospital not named in the registryTaking people
  • BurlingtonHospital not named in the registryTaking people
  • CambridgeHospital not named in the registryTaking people
  • ChicoutimiHospital not named in the registryTaking people
  • EdmontonHospital not named in the registryNot yet recruiting
  • EtobicokeHospital not named in the registryTaking people
  • Greater SudburyHospital not named in the registryTaking people
  • LavalHospital not named in the registryTaking people
  • LévisHospital not named in the registryTaking people
  • London, OntarioHospital not named in the registryTaking people
  • LongueuilHospital not named in the registryTaking people
  • MirabelHospital not named in the registryTaking people
  • MississaugaHospital not named in the registryTaking people
  • MonctonHospital not named in the registryTaking people
  • MontrealHospital not named in the registryTaking people
  • PeterboroughHospital not named in the registryTaking people
  • QuébecHospital not named in the registryTaking people
  • RichmondHospital not named in the registryTaking people
  • RimouskiHospital not named in the registryTaking people
  • Saint-JérômeHospital not named in the registryTaking people
  • SarniaHospital not named in the registryTaking people
  • ScarboroughHospital not named in the registryTaking people
  • SherbrookeHospital not named in the registryTaking people
  • SydneyHospital not named in the registryTaking people
  • TorontoHospital not named in the registryNot yet recruiting
  • Trois-RivièresHospital not named in the registryTaking people
  • WindsorHospital not named in the registryTaking people

About the trial

What the trial wants to find out

The purpose of this study is to evaluate whether zilebesiran versus placebo reduces the risk of cardiovascular (CV) death, nonfatal myocardial infarction (MI), nonfatal stroke, or heart failure (HF) events. This is an event-driven study that will continue until the targeted number of positively adjudicated primary endpoint clinical outcome events (COEs) have been reached.

The 2 groups in the trial

  • Zilebesiran 300 mgTreatment being tested

    Participants will be administered 300 mg zilebesiran subcutaneously (SC) once every 6 months as add-on therapy to their standard of care antihypertensive medications.

    Treatment: Zilebesiran

  • PlaceboPlacebo, for comparison

    Participants will be administered placebo SC once every 6 months as add-on therapy to their standard of care antihypertensive medications.

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record → Contacts and Locations

Print a page for my doctor

Data and sources

Registry record
Listed on ClinicalTrials.gov and on the EU's official list of trials (CTIS).
Official title
ZENITH: A Phase 3 Global, Randomized, Double-blind, Placebo-controlled Study to Evaluate the Efficacy and Safety of Zilebesiran in Addition to Standard of Care in Reducing Major Adverse Cardiovascular Events in Adult Patients With Hypertension Not Adequately Controlled and With Either Established Cardiovascular Disease or High Risk for Cardiovascular Disease
Plain-language title
Tests zilebesiran in adults with high-risk heart disease and high blood pressureGenerated from the registry record. The registry title is the official one.
AI summary
From the trial's eligibility criteria. Read by machine on 12 November 2026.
Record updated
12 November 2026