The following article features coverage from the Society of Immunotherapy of Cancer (SITC) 2020 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Programmed cell death ligand 1 (PD-L1) expression in extracellular vesicles (EVs) was associated with treatment response to immune checkpoint inhibition (ICI) among patients with non-small cell lung cancer (NSCLC), according to the results of a study presented at the virtual Society for Immunotherapy of Cancer 35th Anniversary Annual Meeting & Preconference Programs (SITC 2020).

EVs are double-membrane structures derived from cells that are involved in cell communication and tumor dissemination by carrying and delivering cargo. EVs can be isolated from liquid biopsies and may serve as a surrogate for tumor tissue.

“We sought to evaluate the role of PD-L1 expression in EVs as a predictive biomarker during immunotherapy in NSCLC patients,” Diego de Miguel Perez, PhD, MSc, of the University of Maryland, and presenter of the study, said.

The study included 21 patients with NSCLC who were receiving ICI. Plasma samples were collected at baseline and 8 weeks after treatment initiation. Patients were categorized as responders if their disease showed complete, partial, or stable response, and nonresponders if they developed progressive disease. Plasma EVs were isolated from plasma. PD-L1 expression was assessed in tumor biopsy specimens by immunohistochemistry and in EVs by immunoblot.


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In an analysis of paired plasma samples, PD-L1 expression by EVs was associated with treatment response. ICI nonresponders demonstrated a significant increase in EV PD-L1 expression from baseline compared with responders (P =.043). The area under the curve was 0.85 (90% CI, 0.72-0.97) with a sensitivity of 74.2% and a specificity of 73.5%. PD-L1 tissue expression, however, was not associated with response or EV PD-L1 levels.

Higher EV PD-L1 expression was associated with shorter progression-free survival (hazard ratio [HR], 5.06; P =.025) and overall survival (HR, 4.34; P =.037).

Dr Perez concluded that “EV PD-L1 is a promising candidate for guiding treatment decisions in near real time and for identifying and improving the outcome of NSCLC patients that could benefit from immunotherapy.” He added that further studies are needed to validate the role of EVs as a biomarker.

Read more of Cancer Therapy Advisor‘s coverage of the SITC 2020 meeting by visiting the conference page.

Reference

Perez DM, Russo A, Gunasekaran M, et al. Dynamic change of PD-L1 expression on extracellular vesicles predicts response to immune-checkpoint inhibitors in non-small cell lung cancer patients. Presented at: Society for Immunotherapy of Cancer 35th Anniversary Annual Meeting & Preconference Programs (SITC 2020); November 11-14, 2020. Abstract 31. J Immunother Cancer. 2020;8(Suppl 3):A656–A959.