IFNG and cancer: As our observations clearly provide evidence of IFNγ defects in tumor-specific CTLs, and its negative influence on the cytotoxic and effector responses, further studies should be conducted with larger sample sizes and in different cancer types to decipher the prevalence of IFNγ-deficient tumor-specific CTLs and their relevance to tumor progression and treatment outcome, and the development of novel cancer immunotherapies.