THE CHALLENGES OF USING PD-L1 AS A PREDICTIVE BIOMARKER AND THE THERAPEUTIC APPROACH IN NON-SMALL CELL LUNG CANCER IMMUNOTHERAPY

Lung cancer has gained worldwide a top place in the incidence and mortality related to malignancy. Out of the two different types of pulmonary neoplasms, the histological subtypes included in non-small cell category have received a particular interest because of the various therapeutic targets identified. In the recent years, due to its promising results, the development of immunotherapy is considered a major discovery and has become one of the main therapeutic options along with chemotherapy, radiotherapy and surgery. In order to determine the selection of patients who can obtain beneficial approach from immune checkpoint inhibitors treatment, programmed death-ligand 1 (PD-L1) expression evidenced by immunohistochemistry (IHC) testing has been implemented as a complementary or as a mandatory diagnostic tool in patients with advanced non-small cell lung cancer (NSCLC). The developing studies in this field were concentrated upon the importance of the expression of PD-L1 as a predictive biomarker for treatment response and patients selection validated into clinical daily practice. The aim of this review is to enlighten the factors which influence PD-L1 expression and the utility as biomarker in immunotherapy.