1. Progression-free survival (PFS) [Approximately 6 years]
   To assess the efficacy of Durvalumab monotherapy vs Placebo in terms of PFS
2. Overall Survival (OS) [Approximately 6 years]
   To assess the efficacy of Durvalumab monotherapy vs Placebo in terms of OS

1. Overall Survival (OS) [Approximately 6 years]
   To assess the efficacy of Durvalumab & Tremelimumab combination therapy vs Placebo in terms of OS
2. Objective Response Rate (ORR) [Approximately 6 years]
3. Progression-free survival PFS [Approximately 6 years]
   To assess the efficacy of durvalumab and tremelimumab combination therapy compared to placebo in terms of PFS
4. Progression-free survival at 18 months (PFS18) [Approximately 6 years]
5. Progression-free survival at 24 months (PFS24) [Approximately 6 years]
6. Time to death or distant metastasis (TTDM) [Approximately 6 years]
7. Proportion of patients alive at 24 months (OS24) [Approximately 6 years]
8. Proportion of patients alive at and 36 months (OS36) [Approximately 6 years]
9. Time from randomization to second progression (PFS2) [Approximately 6 years]
10. To assess symptoms and health-related QoL in patients treated withdurvalumab or durvalumab and tremelimumab combination therapy compared to placebo using the EORTC QLQ-C30 v3 [Approximately 6 years]
11. To assess the PK of durvalumab and tremelimumab in blood (peak trough concentration) [Approximately 6 years]
12. Presence of anti-drug antibodies (ADA) for durvalumab and tremelimumab (confirmatory results: positive or negative) [Approximately 6 years]
13. PD-L1 expression in tumor and/or immune cells relative to response/efficacy outcomes (PFS, OS & ORR). [Approximately 6 years]
    To investigate the relationship between PDL1 expression & spatial distribution with Durva (mono) therapy & Durva+Treme (combination) therapy
14. To assess symptoms and health-related QoL in patients treated withdurvalumab or durvalumab and tremelimumab combination therapy compared to placebo using the EORTC QLQ-LC13 [Approximately 6 years]

1. Adverse Events [Approximately 6 years]

• Small Cell Lung Cancer

Drug: Durvalumab

Durvalumab IV (intravenous infusion)

Experimental: Durvalumab + Placebo
Durvalumab monotherapy: Durvalumab (1500 mg intravenous [IV]) q4w in combination with placebo saline solution (IV) q4w for up to 4 doses/cycles each, followed by durvalumab 1500 mg q4w. The first durvalumab monotherapy 1500 mg dose q4w will be 4 weeks after the final dose of durvalumab in combination with placebo saline solution.

• Drug: Durvalumab
• Other: Placebo

Experimental: Durvalumab + Tremelimumab
Durvalumab in combination with tremelimumab: Durvalumab (1500 mg IV) q4w in combination with tremelimumab (75 mg IV) q4w for up to 4 doses/cycles each, followed by durvalumab 1500 mg q4w. The first durvalumab monotherapy 1500 mg dose q4w will be 4 weeks after the final dose of durvalumab in combination with tremelimumab.

• Drug: Durvalumab
• Drug: Tremelimumab

Placebo Comparator: Placebo + Placebo
Placebo: Placebo saline solution (IV) q4w in combination with a second placebo saline solution (IV) q4w for up to 4 doses/cycles each, followed by a single placebo saline solution q4w. The first placebo saline solution monotherapy dose q4w will be 4 weeks after the final dose of the 2 placebo saline solutions in combination.

• Other: Placebo

• Senan S, Okamoto I, Lee GW, Chen Y, Niho S, Mak G, Yao W, Shire N, Jiang H, Cho BC. Design and Rationale for a Phase III, Randomized, Placebo-controlled Trial of Durvalumab With or Without Tremelimumab After Concurrent Chemoradiotherapy for Patients With Limited-stage Small-cell Lung Cancer: The ADRIATIC Study. Clin Lung Cancer. 2020 Mar;21(2):e84-e88. doi: 10.1016/j.cllc.2019.12.006. Epub 2019 Dec 28.

Inclusion Criteria:

• Histologically or cytologically documented limited-stage small cell lung cancer (stage I-III).
• Received 4 cycles of chemotherapy concurrent with radiotherapy, which must be completed within 1 to 42 days prior to randomization and the first dose of IP. Chemotherapy must contain platinum and IV etoposide. Radiotherapy must be either total 60-66 Gy over 6 weeks for the standard QD regimen or total 45 Gy over 3 weeks for hyperfractionated BD schedules.
• PCI may be delivered at the discretion of investigator and local standard of care, and must be conducted after the end of cCRT and completed between 1 to 42 days to first dose of IP.
• 4 .Have not progressed following definitive concurrent chemoradiation 5 .Life expectancy ≥ 12 weeks at Day 1. 6. ECOG 0 or 1 at enrolment.

Exclusion Criteria:

• Extensive-stage SCLC
• Active or prior documented autoimmune or inflammatory disorders
• Uncontrolled intercurrent illness, including but not limited to interstitial lung disease.
• Active infection including tuberculosis, HIV, hepatitis B and C
• Patients who received sequential chemotherapy and radiotherapy (no overlap of RT with chemotherapy)

Studies a U.S. FDA-regulated Drug Product: Yes

Studies a U.S. FDA-regulated Device Product: No

Product Manufactured in and Exported from the U.S.: Not Provided