Therapies targeting immune checkpoints, in particular programmed death 1 (PD-1) and its ligand programmed death ligand 1 (PD-L1), are major new strategies for the treatment of several malignancies including mestatatic non-small cell lung cancer (NSCLC). The identification of predictive biomarkers of response is required, considering efficacy, cost and potential adverse events. Expression of PD-L1 by immunohistochemistry has been associated with higher response rate and overall survival in several clinical trials evaluating anti-PD-1 and anti-PD-L1 monoclonal antibodies. Thus, PD-L1 immunohistochemical companion assays could be required for treatment with some of these therapies in NSCLC. However, heterogeneity in methodologies of PD-L1 assays in terms of primary antibodies and scoring algorithms, and tumor heterogenity for PD-L1 expression are important issues to be considered. More studies are required to compare the different assays, ensure their harmonization and standardization and identify the optimal conditions for testing. PD-L1 expression is likely an imperfect predictive biomarker for patient selection and association with other markers of the tumor immune microenvironment will be probably necessary in the future.
Keywords: Biomarqueur prédictif; Cancer immunotherapy; Carcinome pulmonaire non à petites cellules; Immunothérapies anti-tumorales; Non-small cell lung cancer; PD-L1; Predictive biomarker.
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