Adjuvant Chemotherapy Increases Programmed Death-Ligand 1 (PD-L1) Expression in Non-small Cell Lung Cancer Recurrence

We sought to determine the effect of chemotherapy on programmed death-ligand 1 (PD-L1) expression in non small-cell lung cancer and variability upon PD-L1 expression on initial tumor and recurrence. Our results suggest that chemotherapy might increase PD-L1 expression and demonstrate variability from primary tumor to recurrence. Background: Despite recent studies, the effect of chemotherapy on programmed death-ligand 1 (PD-L1) expression remains controversial. In this study, we investigated whether PD-L1 expression is affected by platinum-based chemotherapy. Furthermore, we evaluated correlation of PD-L1 expression with oncogenic driver alterations. Materials and Methods: We retrospectively evaluated changes in PD-L1 expression by immunohistochemical (IHC) analysis in resected specimens and in biopsies at non-small cell lung cancer recurrence in patients receiving or not adjuvant chemotherapy after surgical resection. Four IHC score groups were defined: TC0 < 1%, T >= 1% and < 5%, TC2 > 5% and < 50%, and TC3 >= 50%. Results: Thirty-six patients with adenocarcinoma were included. Twenty (56%) patients underwent adjuvant chemotherapy, and 16 (44%) patients did not receive adjuvant chemotherapy. PD-L1 expression was present in 10 (28%) of 36 initial tumor specimens. From patients receiving adjuvant chemotherapy, 7 (35%) of 20 tumor biopsies showed significant upregulation in PD-L1 expression at recurrence. In contrast, from patients with no adjuvant therapy, only 2 (12.5%) of 16 showed a change in PD-L1 expression. Six (17%) of 36 patients were PD-L1-negative in the primary tumor and turned positive at recurrence. KRAS mutation was present in 70% of patients expressing PD-L1. Conclusion: PD-L1 expression in non-small cell lung cancer can change from primary to recurrence, implicating the need for re-biopsy at recurrence. Moreover, chemotherapy might increase expression of PD-L1, supporting a combinatorial therapy with chemotherapy and anti-PD(L)1 treatment. (C) 2019 Elsevier Inc. All rights reserved.