An evidence-based appraisal of the surrogate markers of efficacy of allergen immunotherapy.

Purpose of review: The assessment of clinical efficacy of immunotherapy in patients with respiratory allergy is highly affected by variability and lack of validated outcome measures such as symptom and medication scores. At the same time, there is a need to identify reliable predictive surrogate markers or biomarkers that may correlate with real clinical endpoints and lead to individually tailored immunotherapy treatment. Recent findings In-vivo markers, such as early and late skin reaction as well as immunological parameters such as IgE levels, IgG subclasses, mucosal IgA, lymphocyte subsets, cytokines and local and systemic inflammatory markers, have been proposed as potential surrogate markers. Summary: Given the poor reproducibility and surrogacy to clinical outcomes shown in various clinical trials, the decreased availability in daily practice and anticipated high costs, an ideal surrogate marker is still not available to allergists.