Controversies in Allergy: Choosing a Biologic for Patients with Severe Asthma.

The availability of a range of new biological treatments targeting type-2 inflammation has provided new opportunities for patients with more severe asthma. Treatment has a bigger effect on exacerbations than day-to-day symptoms, and efficacy increases with increasing intensity of type-2 airway inflammation as reflected by the blood eosinophil count and fractional exhaled nitric oxide. The similarity of the clinical effects and target populations coupled with the absence of direct head-to-head comparative data makes it difficult to choose the right biologic for a given patient. In this review, we summarize the key efficacy data from phase 3 trials; discuss indirect comparisons; review clinical and laboratory variables that may be associated with a differential response to treatment; outline practical considerations that might be important to individual patients; and suggest an algorithm for choosing the most appropriate biologic to start with and the first choice to switch to.