CD274 and non-small cell lung carcinoma: Although SCLC harbors a high mutation rate (tumor mutational burden/TMB, a biomarker of sensitivity to immunotherapy in SCLC) [60], the pooled prevalence of PD-L1 expression stands at 26.0%, and 22.0% respectively, after excluding the potential outlier studies, which remains lower compared to NSCLC [61].