Preoperative chemoradiotherapy induces multiple pathways related to anti-tumour immunity in rectal cancer.

Background: Rectal cancer treated with preoperative radiotherapy (RT) provides an interesting model to study changes induced on cancer cell immuno-phenotype that could be exploited by immunotherapy interventions to improve prognosis.

Materials And Methods: We assessed the expression of HLA-class-I, β2-microglobulin, TAP1, PD-L1 and STING/IFNβ in preoperative biopsies and respective post-RT surgical specimens from patients with rectal cancer (n = 27). The effect of radiation was further investigated in colorectal adenocarcinoma cell lines HT-29 and Caco-2.