Controversies in Allergy: The potential role of biologics as first line therapy in eosinophilic disorders.

With advances in understanding the role of eosinophils in disease pathogenesis, particularly in the airways, gastrointestinal (GI) tract, and skin, targeting eosinophils or the cytokines that lead to their production, activation, and survival has become an increasingly pursued therapeutic approach. Newly developed biologic agents target eosinophils directly, other cells interacting with or activating eosinophils, or cytokines in the Type 2 inflammatory pathway with specific antibodies. Current treatment paradigms reserve therapy with biologics for patients refractory to or intolerant of corticosteroids or immunosuppressants. Given accumulating data for safety and efficacy of these biologics, however, there is the question of whether targeted treatments should be used earlier in the treatment algorithm. In this article, we discuss the pros and cons of using biologics as first-line therapy for eosinophilic diseases of the airways, GI tract, and skin. We highlight emerging biologic agents and future directions for research, as well as a rationale for the early use of some biologics to prevent tissue damage, disease progression, and organ dysfunction in selected conditions.