Conclusion
There are high PD-L1 expression and infrequent driver mutations in LELCs compared with conventional NSCLCs. The high expression of PD-L1 in EBV and inflammation associated LELC may provide a rationale for immunotherapy in this subtype of lung cancer.
Methods
Sixty-six patients with pulmonary LELCs were investigated. Paraffin-embedded tumor sections were stained with PD-L1 antibody. Tumors with moderate-to-strong membrane staining in ≥5% of tumor cells were positive for PD-L1 overexpression. The presence of driver mutations in the genes for epidermal growth factor receptor (EGFR), KRAS, and BRAF were examined by direct sequencing. Anaplastic lymphoma kinase (ALK) and ROS1 levels were determined by immunohistochemistry. Correlations of PD-L1 expression and driver mutations with clinicopathologic parameters were analyzed.
Results
The overall frequency of PD-L1 overexpression and EGFR mutation was 75.8% and 12.1%, respectively. No KRAS, BRAF, ALK or ROS1 aberrations could be detected. PD-L1 expression was not associated with driver mutations. Multivariate analysis revealed that smoking and advanced stage were independent risk factors for poor overall survival, whereas PD-L1 positivity was not significantly associated with patient outcome.