Abstract IA18: Inactivation of DNA repair to improve immune surveillance

When metastatic cancers are challenged with targeted agents almost invariably a subset of cells insensitive to the drug emerges. As a result, in most instances, targeted therapies are only transiently effective in patients. Strategies to prevent or overcome resistance are therefore essential to design the next generation of clinical trials. How can we overcome the near-certainty of disease recurrence following treatment with targeted agents? Addressing this question means considering as a target not “only” individual oncogenes but also the evolving nature of human tumors. We used colorectal cancer (CRC) as a model system to test the hypothesis that by understanding tumor’s evolution, the emergence of drug resistance can be controlled. We find that to have long-term efficacy, the use of targeted therapies must take into account the continuous evolution of cancer cells, that is to say, therapies must adapt to tumor evolution. Another approach is to unleash the ability of the immune system to recognize drug resistant cells. We tested this possibility in syngeneic mouse models of CRC sensitive to targeted therapies. Our findings indicate that inactivation of DNA repair mechanisms and manipulation of mutational loads can trigger immune surveillance and prolonged therapeutic responses. We postulate that rationally combined targeted and immuno-therapies can restrain tumor evolution, and can limit the emergence of drug resistance thus leading to long-term responses. Citation Format: Alberto Bardelli. Inactivation of DNA repair to improve immune surveillance [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr IA18.