9P - Small-extracellular vesicles derived from NSCLC cells dampen the CD8+ T cell response against tumor

Background

Despite the development of immune checkpoint inhibitors therapy (ICI) in non-small cell lung cancer (NSCLC) patients, most of them eventually experience relapse. Small extracellular vesicles (sEV) are currently emerging as promising biomarkers. They are released by all cell types and can be found in all body fluids. sEV reflect the state of the tumor at distance. Here, we investigated the immunosuppressive role of sEV derived from patient’s NSCLC (NSCLC-sEV) on anti-tumoral CD8+ T cells.

Methods

NSCLC-sEV were purified from NSCLC patient-derived cell lines or from tumor resection. Their immunosuppressive effects were studied by exposing healthy or tumor-infiltrated CD8+ T cells to NSCLC-sEV, where their activation, proliferation and viability were assessed. By NGS, the microRNA cargo of NSCLC-sEV were investigated. Using bioinformatic analysis, we identified potential immunosuppressive microRNAs included into NSCLC-sEV that were tested by direct transfection in CD8+ T cells.

Results

CD8+ T cells exposed to NSCLC-sEV showed reduced expression of their activation markers CD25 and CD45, and decreased secretion of anti-tumoral TNF alpha, granzyme B, and perforin-1, suggesting that they are unable to conduct an efficient anti-tumoral response. NSCLC-sEV also upregulated the CD8+ immune checkpoint markers, such as PD-1, TIGIT, and TIM-3, and decreased the viability and proliferation of exposed CD8+ T cells. Transfection of our candidate miRNAs, miR-29c-3p and miR-181b-5p, into CD8+ T cells induced an inhibition similar to that induced by native NSCLC-sEV.

Conclusions

NSCLC-sEV can impair CD8+ T cell response against the tumor by reducing their activation, proliferation, viability and by increasing the expression of immune checkpoints on their membrane. We demonstrated that these effects could be supported by their immunosuppressive miRNA cargo. Overall, our results describe the immunosuppressive functions of NSCLC-sEV.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

D. Fradin.

Funding

Ligue contre le cancer comité 22, 41, 44; Fondation ARC.

Disclosure

All authors have declared no conflicts of interest.