The nasal allergen challenge (NAC) model can be a useful diagnostic technique for allergic rhinitis. In addition to clinical usage, NACs can be utilised as primary and secondary endpoints in studies assessing allergen immunotherapy (AIT) products for allergic rhinitis treatment. This study will go over the technical elements of the NAC model and offer an overview of current studies that have used NACs to evaluate existing and new AIT therapies. Over the last two years, both titrated and single-dose nasal challenge procedures have been employed to test immunotherapies targeting grass, birch, house dust mite, and cat allergens. Early effectiveness and dose-finding experiments revealed that AIT therapy with standardised extracts or modified forms of entire allergen improved allergy symptoms and nasal tolerance to allergens. In addition, NACs were utilised in two proof-of-concept trials to demonstrate the effectiveness of intralymphatic immunotherapy with two concurrent allergens and subcutaneous immunotherapy with Fel d 1-specific IgG-blocking antibodies.

Nasal challenges, in addition to current medications, are effective in assessing AIT medicines in the early phases of clinical development. However, due to the wide range of challenge methodologies and symptom evaluations available, particular care must be taken in the protocol design in order to match the study results to previous NAC publications.