Jan Burger, MD, PhD, University of Texas MD Anderson Cancer Center, Houston, TX, explains the origins of chronic lymphocytic leukemia (CLL) in the lymph nodes and how the leukemia cells interact with the microenvironment. The pathways that activate leukemia cells can be targeted by drugs. For example, Bruton tyrosine kinase (BTK) inhibitors, ibrutinib and acalabrutinib. Prof. Burger also describes two of his projects. The first explores how to measure and quantify new treatment effects on CLL proliferation. The other investigates the long-lasting effects of ibrutinib to see whether it increased activation-induced cytidine deaminase (AID) expression. In the CLL cell lines, ibrutinib decreased cell proliferation and AID enzyme expression. This interview took place during the European Research Initiative on CLL (ERIC) International Virtual Meeting 2020.