A Study of MEMP1972A in Patients With Allergic Asthma Inadequately Controlled on Inhaled Steroids And A Second Controller (COSTA)

Inclusion Criteria: * Adult patients, 18 to 75 years of age inclusive * Body weight \>/= 40 kg * Physician's diagnosis of asthma for at least 12 months * Evidence of documented bronchodilator reversibility as defined by protocol * Prebronchodilator FEV1 \>/= 40% and \</= 80% predicted at Visit 1 * Required daily use of ICS and a second controller for a minimum of 3 consecutive months prior to Visit 1 * History of at least one protocol-defined asthma exacerbation in the 18 months prior to Visit 1 * Inadequately controlled asthma despite compliance with asthma controller therapy Exclusion Criteria: * Asthma exacerbation requiring systemic steroids in the 30 days prior to Visit 1 * Pre-existing active lung disease other than asthma * Any infection * Clinically significant medical disease that is uncontrolled despite treatment or is likely to require a change in therapy during study or is of unknown etiology * Known immunodeficiency, including but not limited to HIV infection, regardless of treatment status * Current substance abuse * Former smoker with \>10 pack-year history or current smoker; former smokers must have stopped smoking more than 12 months prior to Visit 1 * History of anaphylaxis * Pregnant and lactating women