In keeping with dMMR in other solid tumours, most dMMR PCa demonstrate increased infiltration of CD8+ and CD4+ T cells, with increased expression of the immune checkpoint PD-L1, although notably a significant proportion of dMMR PCa (approximately 45% based on a small study of nine cases) do not demonstrate increased lymphocytic infiltration, potentially accounting for lack of response to ICB in some cases. This evidence concerns the gene CD274 and posterior cortical atrophy.