Evaluating the Efficacy of Ragweed-SPIRE Following Exposure to Ragweed Allergen in an Environmental Exposure Chamber

Inclusion Criteria: * Male or female, aged 18-65 years. * Reliable history consistent with moderate to severe rhinoconjunctivitis on exposure to ragweed for at least the previous two seasons. * Minimum qualifying rhinoconjunctivitis symptom scores * Ragweed-specific Immunoglobulin E (IgE) \> 0.70 kU/L. Exclusion Criteria: * Subjects with a history of ragweed pollen induced asthma * A history of anaphylaxis to ragweed allergen. * FEV1 \< 80 % of predicted. * Subjects who cannot tolerate Baseline Challenge in the EEC. * Subjects for whom administration of epinephrine is contraindicated (e.g. subjects with acute or chronic symptomatic coronary heart disease or severe hypertension). * History of immunopathological diseases (e.g. multiple sclerosis) that in the opinion of the Investigator or the Sponsor could interfere with the results obtained from the study. * A history of severe drug allergy, severe angioedema or anaphylactic reaction to food. * A history of any significant disease or disorder (e.g. cardiovascular, pulmonary, gastrointestinal, liver, renal, neurological, musculoskeletal, endocrine, metabolic, neoplastic/malignant, psychiatric, major physical impairment)