CASPIAN is an open-label, Phase 3 study of durvalumab (D) ± tremelimumab (T) + etoposide and either cisplatin or carboplatin (EP) for pts with 1L ES-SCLC. At the planned interim analysis (data cutoff Mar 11, 2019; 63% maturity), D + EP demonstrated a statistically significant improvement in OS compared with EP alone (HR 0.73 [95% CI 0.59–0.91]; p=0.0047). Researchers present a planned updated analysis of OS for D + EP vs EP and the first results for D + T + EP vs EP.