This is a multicentre, randomized, double-blind, parallel group, placebo-controlled, phase 2 study to designed evaluate the effect of a 300 mg dose of tralokinumab administered subcutaneously every 2 weeks on airway inflammation in adults with asthma inadequately controlled on inhaled corticosteroids (ICS) with or without other controllers. Approximately 80 subjects will be randomized. Subjects will receive tralokinumab, or placebo, administered via subcutaneous injection at the study site, over a 12 week treatment period.