In CLL patients receiving ibrutinib therapy for 2 to 4 years, naïve T cells remain within healthy donor range, PD-1 expression is consistently reduced on chronically activated CD8 T cells, and production of IFNγ and TNFα by antigen-specific CD8 T cells is enhanced following stimulation with CMV or EBV peptides, suggesting that long-term treatment of ibrutinib may reverse the exhausted T cell phenotype (Parry et al., 2019; Solman et al., 2021). The gene discussed is IFNG; the disease is B-cell chronic lymphocytic leukemia.