EGFR and small cell lung carcinoma: Similarly, Nishikawa et al. reported another case with EGFR mutation with negative PD-L1 expression treated with Nivolumab after transformation to SCLC, with limited efficacy, and it significantly downregulated PD-L1 compared with its initial expression in the same tumors, suggesting that EGFR-TKI treatment before transformation may downregulate PD-L1 [86].