In the whole study population (n = 1553, data available for the four trials), the addition of a PD-1/PD-L1 ICI to platinum-etoposide chemotherapy in patients with ES SCLC was associated with a statistically significant increase in ORR [odds ratio (OR) 1.28, 95% CI 1.04–1.57, p = 0.02] (Figure 3). This evidence concerns the gene CD274 and small cell lung carcinoma.