The administration of a subset of human immune cells cultured in the laboratory and known as T lymphocytes that have been engineered to express a chimeric molecule that recognizes tumor cells has shown remarkable antitumor effects in patients with blood tumors. Although there is much promise in these therapies, there is still a need for improvement in safety and efficacy. This project is important to patients because it examines a considerable challenge with these therapies, e.g. their toxicities. The way toxicities are being addressed in this project is unique and holds the promise of alleviating many severe side effects experienced by patients. Additionally, controlling toxicities will be extremely important to the success of treating patients with solid tumors when normal tissues may be targeted. So, there are many advantages to the “safety switch” approach that we propose in this application to alleviate side effects.