A major factor in the pathogenesis of asthma is the development of an allergic inflammatory response to inhaled antigens. Interleukin-4 (IL-4) plays a key role in this response. Binding and inactivating the IL-4 molecule with IL-4R may diminish the allergic asthmatic response by inhibiting activities of IL-4.

Patients are randomized to 1 of 3 treatment groups and, within each group, are stratified by baseline FEV1 cohort. Patients receive either dose level 1 of IL-4R, dose level 2 of IL-4R, or placebo, by aerosol drug delivery device, once a week for 12 weeks. There are frequent clinic visits and several follow-up visits. Physical exams and spirometry are done regularly; immunizations are administered on Day 28; and a skin tests panel is given on Day 84. Blood samples are collected at study visits during treatment and follow-up to test for immunology/serology parameters, chemistry profiles, and asthma-related DNA polymorphisms. Patients are provided with peak flow meters and must demonstrate their proper use so that a peak expiratory flow (PEF) diary and a symptoms diary can be maintained. Selected sites measure exhaled nitric oxide and collect induced sputum samples. Assessments for adverse events are conducted at 16 and 40 weeks following the first study drug treatment.

Inclusion Criteria

Patients may be eligible for this study if they:

• Are 12 to 85 years of age (consent of parent or guardian required if under 18 years).
• Have continuous asthma and are being treated with albuterol MDI only.
• Have reduced lung functions.
• Have a positive reaction to 2 substances as demonstrated with a skin test.
• Have been a nonsmoker for at least 2 years and have not smoked more than 1 pack a day for 5 years or less.
• Agree to use contraception throughout the study.
• Agree not to donate blood throughout the study.
• Are able to use correctly an aerosol drug delivery device.
• Have had an asthma attack on at least 3 of the last 7 days.

Exclusion Criteria

Patients will not be eligible for this study if they:

• Had asthma requiring hospitalization within 6 weeks of beginning study treatment.
• Had asthma requiring emergency room treatment within 12 months of beginning study treatment.
• Had a respiratory infection that affected asthma within 2 weeks of beginning study treatment.
• Had a breathing tube inserted for asthma treatment within 15 years of beginning study treatment.
• Were previously enrolled in a study of soluble IL-4 receptor.
• Have drug abuse, alcohol abuse, or a mental illness that may interfere with the study.
• Have serious medical problems (such as heart or lung problems, uncontrolled high blood pressure, are overweight to the extent that ability to breathe is affected, or have cancer other than skin cancer), diabetes, autoimmune diseases, or HIV.
• Are pregnant or breast-feeding.
• Have used certain drugs.