Durvalumab ± Tremelimumab in Combination With Platinum Based Chemotherapy in Untreated Extensive-Stage Small Cell Lung Cancer (CASPIAN)

Primary objective of this study is to assess the efficacy of durvalumab + tremelimumab + EP treatment compared with EP and the efficacy of durvalumab + EP treatment compared with EP in terms of OS. All patients will be randomized in a 1:1:1 ratio in a stratified manner according to the planned platinum-based therapy for Cycle 1 (cisplatin or carboplatin) to receive treatment with durvalumab + tremelimumab + EP (Arm 1), durvalumab + EP (Arm 2), or standard of care- EP (Arm 3). Arm 1 and Arm 2 patients receive the treatment until confirmed disease progression while Arm 3 patients receive up to 6 cycles of EP and prophylactic cranial irradiation if clinically indicated, at the Investigators' discretion.Patients who have discontinued treatment due to toxicity or symptomatic deterioration, clinical progression, or who have commenced subsequent anticancer therapy will be followed up until confirmed disease progression and for survival. Targeted population are adult patients (aged ≥18 years) with histologically or cytologically documented extensive disease (American Joint Committee on Cancer Stage (7th edition) IV SCLC \[T any, N any,M1 a/b\]), or T3-4 due to multiple lung nodules that are too extensive or have tumor/nodal volume that is too large to be encompassed in a tolerable radiation plan. Patients must have WHO/ECOG performance status of 0 or 1. Tumor assessments will be performed at Screening as baseline with follow-up at Week 6 ±1 week from the date of randomization, at Week 12 ±1 week from the date of randomization, and then every 8 weeks ±1 week until confirmed objective disease progression. An independent data monitoring committee (IDMC) comprised of independent experts will be convened to confirm the safety and tolerability of the proposed dose and schedule of durvalumab ± tremelimumab in combination with platinum based chemotherapy at two early stages of enrolment.