Abstract
Clinical trials for allergen immunotherapy products' development and approval are conducted, aiming to monitor safety and efficacy of them. Symptom scores and the use of rescue medication are the primary clinical endpoints used in the conducted clinical trials, while Quality of Life scores and symptom-free days are measurements also used as secondary endpoints. Although the use of in vitro biomarkers might have been more practical and objective, there are yet no broadly used reliable ones accurately reflecting the clinical effects of allergen immunotherapy. On the contrary, in vivo biomarkers, such as the nasal allergy provocation test, are reliable and successfully used. The aim of this review is to describe how to adapt and use biomarkers and clinical outcomes in the everyday practice of Allergists who perform allergen immunotherapy.