Effectiveness of Cat-PAD to Treat Cat Allergy in Cat Allergic Subjects

Inclusion Criteria: * Minimum 1-year documented history of rhinoconjunctivitis (Nasal symptoms: sneezing, itching, rhinorrhoea, blockage; Ocular symptoms: itching, redness, soreness, watering) on exposure to cats. \[Subjects may also have controlled asthma (GINA classification 1)\]. * Positive skin prick test to cat allergen with a wheal diameter at least 3mm larger than that produced by the negative control. * Subjects must achieve minimum qualifying symptom scores on at least one Symptom Diary Card during EEC exposure on the third and fourth day during the Baseline Challenge. Minimum qualifying symptom scores are defined as a TRSS of at least 10 out of a possible 24 and a TNSS of at least 6 out of a possible 12. Exclusion Criteria: * Subjects with asthma falling under GINA classification 2 (partly controlled) and 3 (uncontrolled). * A history of anaphylaxis to cat allergen. * Subjects with a cat specific IgE \>100 kU/L. * Subjects with an FEV1 \<80% of predicted. * Subjects with an acute phase skin response to cat allergen with a mean wheal diameter \> 50mm. * Subjects who suffer from seasonal allergic rhinoconjunctivitis, and cannot complete the clinical study outside the local pollen season or who have significant allergy to other animal dander that cannot be avoided during the study period. * Subjects who cannot tolerate baseline challenge in the EEC. * Allergen immunotherapy during the last 12 months or any history of Cat Dander immunotherapy. * Subjects for whom administration of adrenaline is contra-indicated (e.g. subjects with acute or chronic symptomatic coronary heart disease or severe hypertension). * Subjects being treated with beta-blockers. * History of immunopathological diseases. * Positive test for Hepatitis B, Hepatitis C or HIV at screening. * Have a history of severe drug allergy or anaphylactic reaction to food. * A known allergy to thioglycerol.