Removal of extracellular kynurenine in the TME by administration of bacterial kynureninase linked to polyethylene glycol (for prolonged systemic retention) increases the frequency of effector CD8+ T cells in the tumor (but not in the periphery), reduces tumor growth, increases survival in a CD8+ cell-dependent manner and potentiates checkpoint inhibition therapy (106). This evidence concerns the gene KYNU and neoplasm.