Study to Evaluate the Safety and Efficacy of CAT-354

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 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 FEV 1 reversibility postbronchodilator of ≥12% and ≥200 mL or have shown such values in a previous test within the last year, or have a positive AHR test result in the last year.
• Pre-bronchodilator FEV 1 value ≥40% of individual predicted value at Visits 1 and 3 8) Uncontrolled asthma consistent with Expert Panel Report (EPR)-3. In the 2 to 4 weeks preceding screening, subjects should have a history of one or more of the following:
• Daytime asthma symptoms ≥2 days/week ii) Nighttime awakening ≥1 night/week iii) Salbutamol use ≥2 days/week.
• An ACQ score ≥1.5 at Visits 1 and 3 (the ACQ is described in Section .7.10.1).
• At least one occurrence of asthma exacerbation in the past year that required an unscheduled medical encounter.
• Women of child-bearing potential, unless surgically sterile (including tubal ligation) and/or at least 2 years postmenopausal must have a negative pregnancy test prior to the first dose of investigational product, and must agree to use - effective methods of avoiding pregnancy (including oral, injectable, transdermal, or implanted contraceptives, intrauterine device, female condom with spermicide, diaphragm with spermicide, cervical cap, use of condom by male sexual partner); or abstinence or sterile sexual partner from screening through Study Day 169. Women of childbearing potential must continue to practice birth control during the study and for at least 2 months after completing the study.
• Men, unless surgically sterile, must likewise practice 2 effective methods of birth control (condom with spermicide) and must use such precautions from Study Day 1 through Study Day 169.
• Otherwise healthy by medical history and physical examination for that age group.
• A chest x-ray or 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 Study 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 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, as determined by medical history and/or subject's verbal report.
• 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 ≤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.