PDCD1 and neoplasm: With the aim of determining the optimal delivery scheme of radiation with immunotherapy targeting the PD-1/PD-L1 axis and TIGIT (T cell immunoreceptor with Ig and ITIM domains), Grapin and colleagues tested in CT26 tumor-bearing mice 3 irradiation schemes (18 × 2Gy, 3 × 8Gy, and 1×16.4Gy).