Ultrasound-Controlled Remote activation of CAR T-cells for localized tumor immunotherapy Chimeric antigen receptor (CAR) T cells show potential as paradigm-shifting therapeutic agents for cancer treatment. CAR-T based immunotherapy, however, can have off-target activity against normal cells and cause life-threatening adverse reactions such as cytokine storms. To mitigate this side effect, we propose to explore high-precision focused ultrasound as a means to confine CAR T cell activation within solid tumor tissue space. In the proposed work, we will use ultrasound to deliver energy safely and noninvasively into small volumes of tissue deep inside the body. We will develop technology and protocols for ultrasound-guided remote-activation of CAR expression in T-cells, which are clinically compatible and able to convert ultrasound waves into short pulses of local heat generation. Specifically, we will engineer molecular thermo-sensors (acousto-sensors) into T-cells along with genetic transducing modules (GTMs), and use focused ultrasound to produce short pulsed heat to activated CAR therapeutic response for focal targeting on solid tumors. We will incorporate reporters to provide direct detection of therapeutic responses, and use the information to calibrate and optimize the system. Therefore, three specific aims are proposed: (1) Develop ultrasound-activatable thermo-sensors and GTMs; (2) Engineer ultrasound-activatable CAR T-cells; (3) Examine the immunotherapeutic efficacy CAR T-cells against solid tumors in vivo. Upon success, this first-of-kind research will specifically transduce remote ultrasound stimulation into genetic expression of T-cells for locally controlled immunotherapy. This approach to solid tumor immunotherapy is expected to open new opportunities to integrate engineering with medicine, and result in many successful translations from fundamental science and engineering to applications with clinical utility.