Ferrara et al. found that high circulating levels of a specific CD8+ T cell subset with a senescent immune phenotype (SIP, lacking expression of CD28 and expressing CD57 and KLRG1) prior to therapy associated with worse clinical response (p = 0.002), and reduced PFS (p < 0.0001) and OS (p = 0.007) in patients with stage III-IV NSCLC (n = 83) receiving anti-PD-(L)1 [73]. The gene discussed is CD8A; the disease is non-small cell lung carcinoma.