Radiation-inducible immunotherapy for cancer: senescent tumor cells as a cancer vaccine.

Radiotherapy offers an effective treatment for advanced cancer but local and distant failures remain a significant challenge. Here, we treated melanoma and pancreatic carcinoma in syngeneic mice with ionizing radiation (IR) combined with the poly(ADP-ribose) polymerase inhibitor (PARPi) veliparib to inhibit DNA repair and promote accelerated senescence. Based on prior work implicating cytotoxic T lymphocytes (CTLs) as key mediators of radiation effects, we discovered that senescent tumor cells induced by radiation and veliparib express immunostimulatory cytokines to activate CTLs that mediate an effective antitumor response.