In the IMPower133 study in ES-SCLC patients treated with first-line atezolizumab-PE derived benefit regardless of PD-L1 expression or blood TMB (bTMB), although patients with a bTMB ≥ 16 muts/Mb had a longer OS in the atezolizumab group compared to those with a bTMB < 16 muts/Mb [24]. This evidence concerns the gene CD274 and small cell lung carcinoma.