The ongoing phase 3 CASPIAN study (NCT03043872) is investigating the efficacy and safety of first-line durvalumab, with or without the anti-cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) antibody tremelimumab, in combination with EP, compared with EP alone in patients with ES-SCLC [7]. Here, CTLA4 is linked to small cell lung carcinoma.