Prognostic role of proliferating CD8 cytotoxic Tcells in human cancers.

Purpose: Expansion of CD8 cytotoxic Tlymphocytes is a prerequisite for anti-cancer immune activity and has gained interest in the era of immune checkpoint therapy.

Methods: To understand the CD8 T cell dynamics in the tumor microenvironment, we used multiplex fluorescence immunohistochemistry to quantitate CD8 proliferation (Ki67 co-expression) in tissue microarrays from 1107 colorectal, 642 renal cell, 1066 breast, 375 ovarian, 451 pancreatic and 347 gastric cancer samples.

Results: The density and the percentage of proliferating (Ki67) CD8 T cells were both highly variable between tumor types as well as between patients with the same tumor type.