Circulating predictive markers of immune checkpoint inhibitors in non-small cell lung cancer

Abstract

Immune checkpoint inhibitors (ICIs) alone or in combination with chemotherapy have become one of the key approaches in the treatment of patients with advanced non-small cell lung cancer (NSCLC). Evaluation of level of PD-L1 (ligand of the programmed cell death receptor 1) expression on tumor cells using immunohistochemistry is the only approved option for determining the indications of ICIs in this group of patients. However, despite high level of PD-L1 expression, up to 80 % of patients do not respond to therapy due to the presence of primary or acquired resistance, which determines the limited effectiveness of ICI. In addition, 8–17 % of PD-L1-negative patients with NSCLC are also able to respond to ICIs. The limitation of this marker is that it does not allow assessing both intratumoral and systemic immune status. It is necessary to search for additional predictive markers to improve the accuracy of the selection of candidates for immunotherapy, which will avoid costs, wasted time, and a high risk of immune-related adverse events in potentially unresponsive patients. The attention of researchers is devoted to circulating markers in peripheral blood, as a non-invasive alternative to biopsy for predicting and monitoring the response. This review focuses on the most promising immunological markers in peripheral blood as potential predictors of response to ICIs in patients with advanced NSCLC.