CD274 and neoplasm: However, while PD-L1 expression and tumor mutational burden (TMB) have been identified as predictive biomarkers for outcomes with ICIs in other indications, including non-small-cell lung cancer (NSCLC) [13, 14] and metastatic triple-negative breast cancer [15], there is no clear evidence from randomized phase 3 studies that PD-L1 expression or TMB predicts outcomes with immunochemotherapy in ES-SCLC.