MA14.02 Evaluation of PD1/PDL1 Expression on Peripheral Blood Cells Subpopulations in Patients with Non-Small Cell Lung Cancer

Abstract

Currently the immune system is considered an important target of study within the therapeutic alternatives for many tumors that have developed resistance in lung cancer. Many molecules called checkpoints regulate antitumor immunity as PD-L1 it is expressed in tumor cells and is a biomarker for anti PD-L1/PD-1 therapy. PD-1/PD-L1 is expressed on exhausted activated T cells. This signaling pathway is involved in tumor evasion of the immune system. It has recently been demonstrated that the blockade of PD-1 or its ligand PD-L1 and PD-L2, restore the antitumor immune response leading to a durable tumor regression. However, the expression of PD-1/PD-L1 in T cells from peripheral blood of patients with non-small cell lung cancer has not been widely studied. We investigated the expression of PD-1 and its ligands PD-L1 and PD-L2 on peripheral blood T cells subpopulations (CD3+ CD4+ / CD8+) of patients with non-small cell lung cancer. We included 50 NSCLC patients (stage IIIB and IV) naive to treatment and 10 healthy subjects. Immunophenotyping was performed using multiparametric flow cytometry. Analyzing its prognostic significance regarding outcome analysis as well as its potential biomarker. Our results showed that the percentage of PD-1, PD-L1 and PD-L2 expression in peripheral blood cells in NSCLC patients was lower compared to healthy subjects [P<0.005] and the Mean Fluorescence Intensity (MFI) was higher in patients compared to the control group [P<0.001]; The expression of PD-1 in T-helper or CD4+ of NSCLC patients was significantly higher than in cells from control subjects [P<0.001]. Similarly, the expression of PD-1 in T cytotoxic cells or CD8+ patients was significantly higher than in controls [P<0.001]. In the clinical analysis, we found that a higher percentage of PD-1+ CD3+ cells was statistically associated with tobacco exposure [P=0.0160], and de MFI was associated with the non-adenocarcinoma histology [P=0.0001] additionally, the presence of 3 or more metastases was associated to a higher MFI of PD-1 on CD3+ CD8+ [P=0.0490]. In the overall survival (OS) analysis the percentage of CD3+/CD4+/PD-1+ ≤20.91 was associated with a higher median OS [P= 0.045]. Several studies demonstrate the importance of infiltrating PD-1+ T cells within tumors; however these results showed that the PD-1/PD-L1/PDL-2 expression in peripheral blood cells could be used also as a potential biomarkers in NSCLC patients.