Paediatric Safety Study in Cat-PAD

* Inclusion Criteria * Male or female, aged 5-12 years. * Moderate to severe rhinoconjunctivitis on exposure to cats for at least 2 years. * Subjects may optionally also have GINA Step 1 controlled asthma. * Positive skin prick test to cat hair. * Cat dander specific IgE ≥0.35 kU/L. * Exclusion Criteria * Asthma falling under the GINA definitions "partly controlled" and "uncontrolled" or Steps 2 to 5. * FEV1 \<80% of predicted. * Clinically relevant abnormalities detected on physical examination. * History of severe drug allergy, severe angioedema or anaphylactic reaction to food.