Anti-TSLP (AMG 157) Plus Antigen-Specific Immunotherapy for Induction of Tolerance in Individuals With Cat Allergy

This study will implement the concept referred to as "allergen-plus," which aims to enhance the disease-modifying mechanisms of allergen-specific immunotherapy by combining it with other anti-inflammatory or immune-modulating agents. Thymic stromal lymphopoietin (TSLP) is a cytokine which appears to be instrumental in both initiating and maintaining allergic sensitivity to antigens, and Immune Tolerance Network (ITN) investigators hypothesize that blocking TSLP during the administration of cat immunotherapy will induce durable immune changes that lead to tolerance. CATNIP will be conducted at multiple sites in the US and enroll cat-allergic adults who will be randomized to four possible treatment groups: immunotherapy plus MEDI9929/AMG 157, immunotherapy plus placebo, placebo plus MEDI9929/AMG 157, or two corresponding placebos. This study is specifically enrolling cat allergic individuals who do not live with cats in order to limit exposure to the allergen outside of the study. Treatment will be given for about one year, followed by one year off therapy.