GZMB and neoplasm: MDSC-induced T cell dysregulation and inhibition of CTL responses remain a common feature in cancer pathogenesis.49 This immune dysregulation of CD8+ T cells and impaired CTL effector responses can be attributed to prevailing immunosuppressive conditions in the tumour microenvironment.50,51 In the present study, we found that ibrutinib treatment was associated with a significant enhancement of CTL activity as evident by significantly elevated levels of Granzyme B, IL-2, IFN-γ, and TNF-α production.