Expression and correlation of PD-L1 and HER2 in oesophageal squamous cell carcinoma

Aims: In recent years, patients with programmed cell death-Ligand 1 (PD-L1)-positive oesophageal squamous cell carcinoma (OSCC) have been able to benefit from immunotherapy. However, method for improving the treatment efficacy of PD-L1-positive patients is a problem that needs further consideration. Studies on the relationship between human epidermal growth factor receptor 2 (HER2) and PD-L1 expression have recently been reported in certain cancers, but the relationship between PD-L1 and HER2 expression in OSCC is still unclear.

Methods: A total of 263 patients with OSCC were included in the study. PD-L1 protein expression and HER2 protein expression were analysed by immunohistochemistry (IHC), and fluorescence in situ hybridisation (FISH) was performed to assess HER2 gene amplification. The significance of differences between HER2 status, PD-L1 status and clinicopathological parameters was assessed. The relationship between PD-L1 status and HER2 status was examined.

Results: Of the 263 OSCC cases, the PD-L1-positive expression rates were 39.2% and 77.2% in OSCC for Tumour Proportion Score (TPS) and Combined Positive Score (CPS), respectively, and PD-L1 expression was associated with the degree of tumour differentiation. The HER2 expression was positive in 24% (63/263) of cases based on IHC and FISH. HER2 expression was not significantly associated with clinicopathological characteristics. PD-L1 TPS expression and CPS expression were significantly positively correlated with HER2 expression in OSCC.

Conclusions: PD-L1 expression was significantly positively correlated with HER2 expression in OSCC. The results provide valuable insight for the future application of HER2-targeted therapy combined with immunotherapy in OSCC.