Clinical Significance of PD-L1+ Exosomes in Plasma of Head and Neck Cancer Patients

Levels of PD-L1 carried by exosomes correlated with patients’ disease activity, the UICC stage and the lymph node status (P = 0.0008–0.013). In contrast, plasma levels of sPD-L1 or exosome PD-1 levels did not correlate with any clinicopathologic parameters. CD69 expression levels were inhibited (P < 0.03) by coincubation with PD-L1high but not by PD-L1low exosomes. Blocking of PD-L1+ exosome signaling to PD-1+ T cells attenuated immune suppression.

PD-L1 levels on exosomes, but not levels of sPD-L1, associated with disease progression in HNSCC patients. Circulating PD-L1+ exosomes emerge as useful metrics of disease and immune activity in HNSCC patients.