A dangerous potential complication of allo-HSCT is thrombotic microangiopathy (TMA). Jeffrey Laurence, MD, Weill Cornell Medical College, Greenwich, CT, discusses a study (NCT02604420) investigating the level of Masp-2, a key part of lectin-dependent complement activation, following allo-HSCT in adults and its correlation with the development of TMA, which may have implications for anti-complement therapy. This interview took place at the American Society of Hematology (ASH) 2019 Annual Meeting and Exposition in Orlando, FL.