Phenotypic classification of asthma based on a new Type 2‐high and Type 2‐low endotypic classification: It all began with Rackemann

Background: Asthma is now recognized as a heterogeneous collection of disease entities associated with different clinical phenotypic presentations and diverse endotypic mechanisms. Recently, a new system of nomenclature of asthma has evolved by using a type 2 (T2) high and T2-low endotypic classification that has proven useful for diagnosis and for choosing the right biologic for patients with asthma. Aim: The purpose of this report was to provide an overview of molecular endotypes, asthma phenotypes, and existing biomarkers, with a focus on the new classification system of T2 and non-T2 pathways in the historical context of the contributions of Francis M. Rackemann, M.D., that set the stage both for our current understanding of the spectrum of disease entities of asthma and for the basis for the use of emerging biologics for the treatment of these disorders. Methods: This article was based on literature review of PubMed and the author’s own research and clinical experiences. Results: Currently, the therapy for asthma is being directed to a treatment strategy based on patient-specific phenotypic characteristics and underlying endotypic mechanisms of tissue injury that focus on a T2-high and T2-low airway inflammation classification. Based on this classification, the clinician is provided with a useful treatment stratagem for choosing the right biologic for personalized care of patients with asthma. Although not perfect in its total applicability, it affords a guide in helping to choose among the currently available biologics, the most appropriate one, as well as those that inevitably will become available. Conclusion: The phenotypic classification of asthma described in this report began with the clinical observations that were made by of an astute clinician long before the supernova emergence of information related to T2-high and T2-low immune function. Rackemann’s legacy to clinical allergy practice once again illustrates that science and technology can best progress through the energizing force of clinical observation.