Study to Evaluate the Safety and Efficacy of CAT-354

This is a Phase 2a, randomized, double-blind, placebo-controlled, parallel-arm study to evaluate the efficacy and safety of 3 subcutaneous (SC) treatment regimens of CAT-354 in adult subjects with uncontrolled, moderate-to-severe, persistent asthma.

Study MI-CP199, a Phase 2a, randomized, double-blind, placebo-controlled, parallel-arm, multicenter study will evaluate the effect of 3 SC treatment regimens of CAT-354 on asthma control in adults with uncontrolled, moderate-to-severe, persistent asthma.

Eligibility Criteria:
Inclusion Criteria:

* Male or female subjects
* Age 18 to 65 years at the time of Screening
* Subjects must have a body mass index (BMI) between 18 and 40 kilogram per square meter (kg/m\^2)
* Written informed consent obtained from the subject prior to performing any protocol related procedures, including Screening evaluations
* Physician-diagnosed moderate-to-severe, persistent asthma requiring treatment with appropriate asthma controller medication
* Shows forced expiratory volume in 1 second (FEV1) reversibility postbronchodilator of greater than or equal to (\>=)12 percent and \>=200 milliliter (mL) or have shown such values in a previous test within the last year, or have a positive airway hyperresponsiveness (AHR) test result in the last year
* Pre-bronchodilator FEV 1 value \>=40 percent of individual predicted value at Visits 1 and 3
* Uncontrolled asthma consistent with Expert Panel Report (EPR)-3. In the 2 to 4 weeks preceding Screening, subjects should have a history of 1 or more of the following: Daytime asthma symptoms \>=2 days/week, Nighttime awakening \>=1 night/week, Salbutamol use \>=2 days/week
* An Asthma control questionnaire (ACQ) score \>=1.5 at Visits 1 and 3
* At least 1 occurrence of asthma exacerbation in the past year that required an unscheduled medical encounter
* Men, unless surgically sterile, must likewise practice 2 effective methods of birth control (condom with spermicide) and must use such precautions from Day 1 through Study Day 169
* Otherwise healthy by medical history and physical examination for that age group
* A chest x-ray or computed tomography (CT) scan within the previous 12 months with no findings suggestive of acute or chronic respiratory pathology other than asthma
* Ability and willingness to complete the follow-up period until Day 169 as required by the protocol.

Exclusion Criteria:

* Known history of allergy or reaction to any component of the investigational product formulation
* Acute illness other than asthma at the start of the study
* History of an active infection within 4 weeks prior to Screening, or evidence of clinically significant active infection, including ongoing chronic infection
* History of ingestion of untreated water in a location known to be infected with parasites, resulting in acute or chronic diarrhea; or a diagnosis of parasitic infection within 6 months prior to Screening
* Use of immunosuppressive medication (except oral prednisone up to 10 milligram/day (mg/day) and inhaled and topical corticosteroids) within 30 days before randomization into the study
* Receipt of immunoglobulin or blood products within 30 days before randomization into the study
* Receipt of any investigational drug therapy or use of any biologicals including omalizumab within 6 months before the first dose of investigational product in this study or within 5 half-lives of an investigational agent or biologic, whichever is longer
* History of any known immunodeficiency disorder
* A positive hepatitis B surface antigen, or hepatitis C virus antibody
* A positive human immunodeficiency virus test or is taking antiretroviral medications, as determined by medical history and/or subject's verbal report
* A live or attenuated vaccination received within 4 weeks prior to Screening
* Previous medical history, or evidence, of an intercurrent illness that may compromise the safety of the subject in the study
* History of clinically significant abnormality on electrocardiogram (ECG) in the opinion of the investigator
* Lactation (women)
* History of treatment for alcohol or drug abuse within the past year
* History suggestive of chronic obstructive pulmonary disease (COPD) and of cigarette smoking \>=10 pack-years
* Evidence of any systemic disease on physical examination
* History of cancer, apart from basal cell carcinoma or in situ carcinoma of the cervix treated with apparent success with curative therapy less than or equal to (\<=)1 year prior to Study Day 1 or other malignancies treated with apparent success with curative therapy \<=5 years prior to entry
* Known exposure to inhaled occupational agents or fumes
* Any condition (eg, cystic fibrosis \[CF\] or COPD) that, in the opinion of the investigator, would interfere with evaluation of the investigational product or interpretation of study results
* Individuals who are legally institutionalized
* Employees of the clinical study site or any other individuals involved with the conduct of the study, or family members of such individuals.