PD-L1 expression by tumor cell-lines: a predictive marker in melanoma

Abstract

Prognostic biomarkers for melanoma patients after lymph node resection are of clinical relevance and could thus enable the identification of patients who therefore would most benefit from adjuvant treatment. The aim of this work was to determine, using an in vitro model, whether immune-related biomarkers such as MHC-class I and II, melanoma associated antigens, IDO1 and PD-L1, could also be relevant to predict the risk of relapse of stage III melanoma patients after lymph node resection.

We established tumor cell lines from metastatic lymph nodes of 50 melanoma patients. The expression of investigated biomarkers was determined on untreated and IFN-γ treated melanoma cell lines using flow cytometry. Among the selected biomarkers, the IFN-γ induced expression of PD-L1 and IDO1 was associated with an increased risk of relapse (p=0.0001 and p=0.013, respectively) and was also associated with death for IDO1 (p=0.0005). In the future, this immunologic signature could permit the identification of patients at higher risk of relapse, and justifying an adjuvant treatment using immunotherapy.

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