Background: Expression level of PD-L1 mRNA as determined by next generation sequencing (NGS) is becoming more routinely available in cancer profiling. We explored the relevance of PD-L1 mRNA expression as detected by RNA sequencing in providing information relevant to clinical practice and compared lung cancer with colorectal cancer in activating interferon pathway. Methods: RNA was extracted from 160 non-small cell lung cancers and 53 colorectal cancers (CRC) as well as from 103 samples of various types cancers that were also analyzed for PD-L1 expression by IHC. The RNA sequencing was performed using a targeted panel of 1408 genes. IHC for PD-L1 staining was performed with the FDA-cleared diagnostic assay using the 22C3 antibody. Results: Based on comparing the number of PD-L1 IHC positive tumor cells and CD274 mRNA, significant correlation between the two methodology can be demonstrated as continuous variables (P < 0.0001) as well as when the IHC positivity is grouped as 0 to 1, 2 to 9, 10 to 49, and > = 50 (P < 0.0001). However, cancers with PD-L1 by IHC > 50% had distinctly higher levels of CD274 mRNA, while all other levels of IHC positivity showed significant overlap. Overall lung cancer showed significantly higher levels in STAT1 (P = 0.002), STAT3 (P < 0.0001), STAT4 (P = 0.005), PTPN2 (0.002) as compared with CRC. However, when only CRC cases that show PD-L1 overexpression were considered, there was no significant difference in the expression in any of these genes as compared lung cancer cases that also show PD-L1 overexpression. The only difference is that lung cancer cases with PD-L1 overexpression showed higher levels of IKBKE mRNA as compared with CRC cases with PD-L1 overexpression (P = 0.004). In addition, lung cancer overall showed higher levels of PD-L2 (P = 0.0002), PD-1 (P = 0.0002), CD8A (P < 0.0001), and CD19 (P = 0.0008), but CRC with PD-L1 overexpression showed no difference in the expression of any of these genes when compared to lung cancer cases with PD-L1 overexpression. Conclusions: While CRC shows overall significantly lower RNA levels of PD-L1, PD-L2, PD-1, CD19, CD8A and genes involved in interferon pathway, CRC cases with high expression of PD-L1 mRNA are similar to lung cancer high expressors of PD-L1. Furthermore, PD-L1 quantification using NGS testing can be used to select patient for immunotherapy and might provide valuable information on co-markers that may provide better insight to selecting patients for immunotherapy.