MKI67 and neoplasm: This uniform increases in 4-1BB and Ki67+CD8+ T cells, was accompanied by an insignificant change in the 4-1BB+ CD4+ T cell population (Extended Data Fig. 10e,f) and no difference between responder, none-responders and flare for the latter (Supplementary Fig. 10a), supporting our hypothesis that CD8+ T cells expressing 4-1BB reflect the expansion of a tumor-specific response.