CD80 and head and neck squamous cell carcinoma: To confirm the validity of our hypothesis, TNBC, HNSCC and PDAC cell lines were treated with increasing doses of radiotherapy (6Gy, 9Gy, 12Gy) administered with fractionated schedule and then cocultured with B7-H3 CAR T cells at different effector to target cell (E:T) ratios.