This study is researching a drug called dupilumab. The study is focused on patients who have uncontrolled asthma. Asthma is a condition where the airways narrow and swell, making it difficult to breathe. Uncontrolled asthma means that patients are still having frequent symptoms while taking their current asthma medication.

The aim of the study is to see which regimen is more effective: taking dupilumab with an inhaled asthma medication or only taking a higher dose of the inhaled asthma medication. The type of asthma medication that will be used is a combination inhaled corticosteroid and long-acting beta-agonist (referred to as an ICS/LABA). Some patients may also receive an additional asthma medication called a long-acting muscarinic antagonist (referred to as a LAMA) if they are already receiving a LAMA.

The study is also looking at:

• What side effects may happen from taking dupilumab

This study is a Phase 3b in Canada Minors will not be enrolled in Denmark

Key Inclusion Criteria:

1. Diagnosis of asthma for ≥12 months, based on the Global Initiative for Asthma (GINA) 2023 guidance document
2. Existing treatment with medium dose ICS/LABA (>250 to 500 μg/day of fluticasone propionate DPI or equivalent, per GINA 2023 guidance document) for at least 3 months with a stable dose ≥1 month prior to visit 1
3. Participants requiring a maximum of 3 controllers for their asthma will be considered eligible for this study
4. Pre-bronchodilator FEV1, as defined in the protocol
5. Reversibility of at least 12% and 200 mL in FEV1 after the administration of 200 to 400 μg albuterol/salbutamol at screening OR a documented history of ≥20% reduction in the FEV1, as defined in the protocol
6. Demonstrated adherence to medium dose ICS/LABA on at least 80% of days during the run-in period
7. ACQ-5 score ≥1.5 at screening (visit 1)
8. History of ≥1 severe exacerbation(s) in the previous year before visit 1, but not in the 30 days immediately preceding visit 1
9. Biomarker criteria: Baseline blood eosinophil count ≥300 cells/μL at visit 1 (~90% of population), as defined in the protocol

Key Exclusion Criteria:

1. Diagnosis of chronic obstructive pulmonary disease (COPD) or other lung diseases which may impair lung function and interfere with treatment assessments
2. Clinical evidence of lung disease(s) other than asthma or imaging (Chest X-ray, computed tomography (CT), magnetic resonance imaging [MRI]) with significant findings within 12 months of visit 1 and up to and including the baseline visit (visit 3)
3. A participant who experiences a severe asthma exacerbation at any time from 1 month prior to the screening visit (visit 1) up to and including the baseline visit (visit 3), as defined in the protocol
4. Weight is less than 30 kilograms
5. Current smoker or cessation of smoking within 6 months prior to visit 1 or previous smoker with a smoking history ≥10 pack-years
6. Severe concomitant illness(es) that, in the Investigator's judgment, would adversely affect the participant's participation in the study, as defined in the protocol
7. Participants cannot be on systemic corticosteroids at any time from 1 month prior to the screening visit (visit 1) through the duration of the run-in period

NOTE: Other protocol-defined Inclusion/Exclusion criteria apply

All Individual Patient Data (IPD) that underlie publicly available results will be considered for sharing.

When Regeneron has :

• received marketing authorization from major health authorities (e.g., FDA, European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), etc.) for the product and indication or has globally discontinued development of the product for all indications on or after April 2020 and has no plans for future development
• made results publicly available (e.g., scientific publication, scientific conference, clinical trial registry)
• the legal authority to share the data, and
• ensured the ability to protect participant privacy

Qualified researchers can submit a proposal for access to individual patient or aggregate level data from a Regeneron-sponsored clinical trial through Vivli. Regeneron's Independent Research Request Evaluation Criteria can be found at: https://www.regeneron.com/sites/default/files/Regeneron-External-Data-Sharing-Policy-and-Independent-Research-Request-Evaluation-Criteria.pdf