Study in Cat-Allergic Patients With Asthma to Evaluate the Efficacy of a Single Dose of REGN1908-1909 to Reduce Bronchoconstriction Upon Cat Allergen Challenge

The primary objective is to evaluate the prophylactic efficacy of REGN1908-1909 (anti-Fel d 1) administered as a single dose on day 1 in cat-allergic asthmatic patients not living with a cat in the prevention of a Controlled Cat Allergen Challenge-induced early asthmatic response (EAR) assessed by measures of lung function (FEV1) compared to placebo-treated patients.

Secondary Efficacy Objectives:

* To evaluate the prophylactic efficacy of REGN1908-1909 administered as a single dose on day 1 in cat-allergic asthmatic patients not living with a cat, in the prevention of a Controlled Cat Allergen Challenge-induced: Allergic rhinitis and Ocular symptoms
* To evaluate the prophylactic efficacy of REGN1908-1909 administered as a single dose on day 1 in cat-allergic asthmatic patients not living with a cat to increase the exposure to cat allergen, measured as a product of minute ventilation and time, required to induce EAR in a Controlled Cat Allergen Challenge as compared to placebo patients

Secondary Safety Objective:

* To evaluate the safety and tolerability of REGN1908-1909 vs. placebo in patients with cat allergen-triggered asthma


Eligibility Criteria:
Key Inclusion Criteria:

* Documented or patient reported history (for at least 2 years) of symptomatic cat allergen-triggered asthma with rhinitis with or without conjunctivitis
* No cat exposure at home for the past year and must continue having no exposure at home during the study; cat exposure outside of the home shall be avoided for at least one week prior to any Cat Allergen Challenge and during the defined follow-up period
* Less than 10 pack-years of smoking history

Key Exclusion Criteria:

* Positive human immunodeficiency virus (HIV) test
* Positive hepatitis test (HBsAg and hepatitis C antibody)
* History of significant multiple and/or severe allergies (including latex gloves) or has had an anaphylactic reaction or significant intolerability to prescription or nonprescription drugs or food
* Participation in a prior REGN1908-1909 clinical trial
* History of severe anaphylactic or severe asthmatic reactions to cat exposure
* Active lung disease other than asthma
* Treatment with an investigational drug within 2 months or within 5 half-lives (if known), whichever is longer, prior to screening
* Persistent chronic or recurring acute infection requiring treatment with antibiotics, antivirals, or antifungals, or any untreated respiratory infections within 4 weeks prior to screening
* History of life-threatening asthma, defined as an asthma episode that required intubation and/or was associated with hypercapnia, respiratory arrest, and/or hypoxic seizures
* Treatment of asthma requiring systemic (oral or parenteral) corticosteroid treatment more than twice within 12 months or once within 3 months prior to screening or has been hospitalized or has attended the ER/Urgent Care facility for asthma more than twice in prior 12 months before screening.
* History of hypersensitivity to corticosteroids or antihistamines, or drug treatment excipient

Note: Other protocol defined Inclusion/Exclusion Criteria Apply