CD8A and cancer: The selective pressure of the highly cytotoxic immune phenotype might, however, result in the development of specific immune evasion mechanisms in some of these tumours.61 This could explain findings such as the unexpected presence of ATM mutations in PDACs with an immune-rich microenvironment.52 As the DNA damage response protein ATM is known to drive cytokine production, leading to increased recruitment of CD8+ cytotoxic T cells,57 abrogation of this function through mutation might represent an adaptive mechanism of the cancer cells in their effort to reduce immunotoxicity.