Conclusion
In patients with recurrent NSCLC, especially those who have received chemotherapy previously, a recent re-biopsy sample is required to determine whether PD-1/PD-L1 inhibitors should be used for treatment or not.
Methods
A total of 36 NSCLC patients for whom both the surgically resected specimens of the primary tumors and re-biopsy specimens of the recurrent tumors were available were enrolled in this study. The PD-L1 expression status and tumor-infiltrating CD8-positive T lymphocytes (CD8+TILs) count were measured in paired samples by immunohistochemistry. The concordance rate in the tumor immune microenvironment (TIME) classification based on the PD-L1 expression status and CD8+TILs count was analyzed.
Results
While the PD-L1 expression levels were similar between the surgical and re-biopsy specimens in 77.8% of cases, in 16.7% of cases, the expression levels were higher in the re-biopsy specimens. When the analysis was confined to patients who had received platinum-based chemotherapy, the percentage increased to 42.9%. The TIME classification changed in the re-biopsy specimens as compared to the surgical specimens in one-third of the patients, especially in those who had received chemotherapy previously. The TIME classification in the re-biopsy specimens more closely resembled that in the metastatic lymph nodes as compared to that in the primary tumor.