In this interview, Susan O’Brien, MD, of the University of California, Irvine, CA, talks to us about the next-generation PI3Kδ inhibitor umbralisib for patients with relapsed/refractory lymphoid malignancies. Speaking from the American Society of Hematology (ASH) 2017 Annual Meeting and Exposition in Atlanta, GA, Prof. O’Brien discusses the large-scale safety data presented. She highlights the importance of this data, and compares umbralisib to idelalisib and duvelisib.