The majority of patients with advanced systemic mastocytosis (AdvSM) exhibit D816V mutations of the KIT gene, which presents a promising therapeutic target. Here, Daniel DeAngelo, MD, PhD, of Dana-Farber Cancer Institute, Boston, MA, discusses the clinical trial of avapritinib (previously BLU-285; NCT02561988), a potent and highly selective inhibitor of D816V mutant KIT. Dr DeAngelo highlights the dosing, toxicity, response and complete remission rates observed. This video was recorded at the American Society of Hematology (ASH) 2017 Annual Meeting and Exposition in Atlanta, GA.