Recent studies suggest that durvalumab–tremelimumab combination can provide meaningful clinical benefit in specific tumors such as the subgroup of patients with NSCLC who progressed on PD-1-directed therapy [45], but it will be essential in future studies to assess whether biomarkers of tumor-infiltrating CD8+ and CD4+ T cells at baseline are associated with an increased response to combined PD-L1 and CTLA-4 inhibition and better tolerability of this combination. The gene discussed is CD4; the disease is neoplasm.