The primary objective of the study is to evaluate the efficacy of dupilumab on lung function in participants with Allergic Bronchopulmonary Aspergillosis (ABPA).

The secondary objectives of the study are:

• To evaluate the effects of dupilumab on exacerbations in participants with ABPA
• To evaluate the effects of dupilumab on ABPA-related exacerbations
• To evaluate the effects of dupilumab on hospitalization/emergency department (ED)/urgent care visits in participants with ABPA
• To evaluate the effects of dupilumab on asthma control in participants with ABPA
• To evaluate the effects of dupilumab on health-related quality of life (HRQoL) in participants with ABPA
• To evaluate the effects of dupilumab on serum total immunoglobulin E (IgE) and Aspergillus-specific IgE concentrations
• To evaluate the effects of dupilumab on Fractional exhaled Nitric Oxide (FeNO) levels
• To evaluate safety and tolerability of dupilumab in participants with ABPA
• To evaluate dupilumab concentrations in serum and the incidence of anti-dupilumab antibodies in participants with ABPA

Key Inclusion Criteria:

• Diagnosis of both ABPA and asthma
• On a maintenance therapy for their asthma with controller medication which must include inhaled corticosteroids (ICS) and may include 1 or more additional controller medications including a long-acting beta agonist (LABA), leukotriene receptor antagonist (LTRA), and/or long-acting muscarinic receptor antagonist (LAMA), etc for at least 12 weeks, with a stable dose and regimen with no change in the dose or frequency of administration for at least 4 weeks prior to the screening visit and between the screening and baseline/randomization visits
• For participants on OCS (oral corticosteroid): must be on a chronic stable dose (no change in the dose) of OCS of up to 10 mg/day (for participants taking daily corticosteroids) or up to 30 mg every alternate day (for participants taking alternate day corticosteroids) (prednisone/prednisolone or the equivalent) for at least 4 weeks prior to the screening visit and between the screening and the baseline/randomization visit
• Must have experienced ≥1 severe respiratory exacerbation requiring treatment with systemic corticosteroids or hospitalization or treatment in ED/urgent care within 12 months prior to the screening visit or must be receiving chronic stable low-dose OCS per above criteria

Key Exclusion Criteria:

• Weight less than 30.0 kilograms
• Current smoker or e-cigarette user, cessation of smoking or e-cigarette use within 6 months prior to randomization, or >=10 pack-years smoking history
• Post-bronchodilator FEV1 <30% predicted normal at screening
• Respiratory exacerbation requiring systemic corticosteroids within 4 weeks prior to screening and between screening and baseline visit (for patients on daily or alternate day OCS, exacerbation requiring at least double the maintenance dose of corticosteroids)
• Upper or lower respiratory tract infection within the 4 weeks prior to screening (visit 1) or between the screening and randomization visits
• Significant chronic pulmonary disease other than asthma complicated with ABPA (eg, physician-diagnosed bronchiectasis due to a condition other than ABPA; cystic fibrosis; sarcoidosis; interstitial lung disease not due to ABPA; chronic obstructive pulmonary disease [COPD] not due to ABPA; hypereosinophilic syndrome; etc), a diagnosed pulmonary or systemic disease associated with elevated peripheral eosinophil counts
• Diagnosis or suspected diagnosis of eosinophilic granulomatosis with polyangiitis (EGPA) (also called Churg-Strauss Syndrome)

NOTE: Other protocol defined inclusion / exclusion criteria applies.

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

Individual anonymized participant data will be considered for sharing once the indication has been approved by a regulatory body, if there is legal authority to share the data and there is not a reasonable likelihood of participant re-identification.

Qualified researchers may request access to anonymized patient level data or aggregate study data 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, has the legal authority to share the data, and has made the study results publicly available (eg, scientific publication, scientific conference, clinical trial registry).