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Evaluating tezepelumab for severe asthma in children aged 5 to under 12

A Multicentre, Randomised, Double-Blind, Parallel-Group Placebo-Controlled, Phase 3, Efficacy and Safety Study of Tezepelumab in 5 to < 12 Year Old Children With Severe Uncontrolled Asthma (HORIZON)

Phase 3 Interventional AstraZeneca · NCT06023589

This study is testing if a new asthma treatment called tezepelumab can help children aged 5 to under 12 who have severe asthma feel better and breathe easier.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment231 (estimated)
Ages5 Years to 11 Years
SexAll
SponsorAstraZeneca Industry-sponsored
Drugs / interventionstezepelumab
Locations143 sites (Montgomery, Alabama and 142 other locations)
Trial IDNCT06023589 on ClinicalTrials.gov

What this trial studies

This phase-3 clinical trial investigates the efficacy and safety of tezepelumab, a monoclonal antibody, in children aged 5 to less than 12 years with severe uncontrolled asthma. Participants will undergo a screening period followed by a 52-week double-blind treatment phase where they will receive either tezepelumab or a placebo via subcutaneous injections. After the treatment phase, there will be a 12-week follow-up period, with an optional extension for those who qualify to continue receiving tezepelumab. The study aims to provide insights into the effectiveness of this treatment in managing severe asthma in pediatric patients.

Who should consider this trial

Good fit: Ideal candidates are children aged 5 to less than 12 years with a documented diagnosis of severe asthma and currently on medium to high-dose inhaled corticosteroids.

Not a fit: Patients who do not have a diagnosis of severe asthma or are not currently on appropriate asthma medications may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could significantly improve asthma control and quality of life for children suffering from severe asthma.

How similar studies have performed: Previous studies have shown promise with monoclonal antibody treatments for asthma, indicating potential for success with this approach.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

1. Written informed consent from (ICF) at least one parent/caregiver (as per local guidelines) and accompanying informed assent from the participant (where the participant is able to provide assent) prior to admission to the study.
2. Participants must be 5 to \< 12 years of age, at the time of signing the assent form (as applicable per local guidelines) and their caregivers signing the ICF and at Visit 3.
3. Documented physician diagnosis of severe asthma confirmed and evaluated for at least 6 months prior to Visit 1.
4. Documented physician-prescribed treatment with a total daily dose of either medium or high dose, for at least 3 months with stable dose ≥ 1 month prior to Visit 1.
5. Documented treatment with at least one additional maintenance asthma controller medication is required according to local guidelines and standard of care; (long-acting beta agonist, leukotriene receptor antagonist, long-acting muscarinic antagonist) for at least 3 months with stable dose ≥ 1 month prior to Visit 1.
6. Supportive evidence of asthma as documented by one of the following:

   1. Post-BD (albuterol/salbutamol) responsiveness of FEV1 ≥ 10% during Screening (15 to 30 min after administration of 4 puffs of albuterol/salbutamol with a maximum of 12 puffs of reliever medication only if tolerated by the participant) at either Visit 1 or Visit 2.

      If (a) is not achieved at Visit 1 or Visit 2, historical documentation by any of the below prior to Visit 1:
   2. Post-BD responsiveness of FEV1 ≥ 10%.
   3. Positive methacholine challenge defined as provocative concentration (PC20) of ≤ 16 mg/mL.
   4. PEF average daily diurnal variability \> 13% over a 2-week period.
   5. Variability of FEV1 ≥ 12% between any two clinical visits.
   6. Positive exercise challenge test (defined as a fall in FEV1 of \> 12%).
   7. FeNO ≥ 20 ppb despite confirmed ICS maintenance therapy.
7. History of at least 2 severe asthma exacerbation events OR 1 severe asthma exacerbation event resulting in hospitalisation within 12 months prior to Visit 1.
8. Pre-BD FEV1 \>50% and ≤ 95%PN OR FEV1/forced vital capacity (FVC) ratio ≤ 0.85 at either Visit 1 or Visit 2.
9. Evidence of uncontrolled asthma, with at least 1 of the below criteria:

   1. ACQ-IA score ≥ 1.5 at least once during Screening/Run-in, including Visit 3 (prior to Randomisation) for participants ≥ 6 years old at Screening.
   2. Use of reliever medication, other than as a preventive for exercise induced bronchospasm, on 3 or more days per week for at least 1 week during the Screening/Run-in period.
   3. Sleep awakening due to asthma symptoms requiring use of reliever medication at least once during the Screening/Run-in period.
   4. Asthma symptoms 3 or more days per week in at least 1 week during the Screening/Run-in period.
10. Body weight ≥ 16 kg at Visit 1 (Screening) and Visit 3 (Randomisation).

Exclusion Criteria:

1. History of vocal cord dysfunction, cystic fibrosis, primary ciliary dyskinesia, or chronic rhinosinusitis with nasal polyposis.
2. History of any clinically significant disease or disorder other than asthma which, in the opinion of the investigator, may either put the participant at risk because of participation in the study, or influence the results or the participant's ability to participate in the study.
3. History of a clinically significant deterioration in asthma or asthma exacerbation including those requiring use of systemic corticosteroids or increase in the maintenance dose of oral corticosteroids within 30 days prior to Visit 1.
4. Change in ICS dose within 1 month prior to Visit 1.
5. History of a life-threatening asthma exacerbation resulting in a hypoxic seizure or requiring intubation.

Where this trial is running

Montgomery, Alabama and 142 other locations

+93 more sites — see ClinicalTrials.gov for the full list.

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions AsthmaUncontrolled AsthmaSevere Uncontrolled AsthmaHuman monoclonal antibody cytokine
Last reviewed 2026-06-10 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.