Dr. Waller's research focus is in enhancing immune reconstitution after stem cell transplant and developing cell and small-molecule based cancer immunotherapeutics. His current research activities include pre-clinical and clinical studies focused on the role of donor immune cells in optimizing anti-tumor immunity after allogenic transplantation, enhancing functional properties of chimeric-antigen-receptor T cells, and blocking novel immune check-point pathways in cancer. His NIH-funded basic and translational research lab uses mouse models and performs immunological analyses of clinical samples from patients. He has active translational research activities and serves as a principal investigator on institutional and national cooperative group clinical trials.