The landscape of PD-L1 expression and somatic mutations in hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver, and becoming the third-leading cause of cancer-related mortality worldwide. Despite the immune checkpoint inhibitors and molecular targeted therapies have shown preferable efficacy in HCC, large number of HCC patients do not respond effectively to anti-PD-1 reagents. Besides, the accumulation of genetic mutations in cancer cells may lead to the therapy resistant. Hence, there are clinical gaps between genetic and transcriptomic biomarkers for the HCC treatment. Methods: To investigate the genetic mapping of liver cancer, targeted deep sequencing (TDS) and bioinformatics analysis were performed on hepatocellular carcinoma (HCC) tumor tissues and matched blood samples. Furthermore, copy number variants (CNVs) and Tumor mutation burden (TMB) were calculated. Immunohistochemistry was applied to determine the PD-L1 expression in HCC tumor tissues. Clinical characteristic, PD-L1 expression, and the TMB were analyzed in 32 HCC patients. Results: This study indicated that the PD-L1 positive patients exhibited a lower TMB compared to the PD-L1 negative group, and PD-L1 positive patients were more likely to suffer from aggressive clinicopathologic features than PD-L1 negative patients. We also verified the top 30 mutated genes, including TP53, CTNNB1, KMT2D, AXIN1, ALK, and NOTCH1, in our dataset. Our results indicated that PD-L1 positive patients possessed more tumors with vascular invasion and advanced CCLC stage. Moreover, PD-L1 positive patients exhibited a lower TMB compared to the PD-L1 negative group. Conclusions: These findings could improve our understanding of the effects of immune checkpoint therapies on prognosis, and could facilitate the monitoring of somatic mutations in HCC.