EpCAM⁺ Extracellular Vesicle PD-L1 Dynamics as a Predictive Biomarker of Immune Checkpoint Blockade Response

Area of Science:

• Oncology
• Biomarker Discovery
• Immunotherapy

Background:

• Programmed death-ligand 1 (PD-L1) blockade enhances cancer treatment outcomes.
• Reliable biomarkers are needed to monitor patient responses to PD-L1 therapies.
• Extracellular vesicles (EVs) are emerging as potential sources for non-invasive biomarkers.

Purpose of the Study:

• To develop and validate a surface-enhanced Raman scattering (SERS)-based platform for ultrasensitive detection of PD-L1 on circulating EpCAM+ EVs.
• To investigate the correlation between dynamic changes in PD-L1 expression on EVs and clinical outcomes in cancer patients undergoing immunotherapy.
• To establish EpCAM+ EV PD-L1 as a predictive biomarker for long-term responses to immune checkpoint blockade.

Main Methods:

• Development of a SERS platform for ultrasensitive PD-L1 detection on EpCAM+ EVs.
• Validation of the platform using EVs from interferon-gamma-treated tumor cell lines.
• Application of the platform to paired pre- and post-treatment plasma samples from non-small-cell lung cancer and head and neck squamous cell carcinoma patients receiving anti-PD-(L)1 immunotherapy.

Main Results:

• The SERS platform demonstrated ultrasensitive detection of PD-L1 on EpCAM+ EVs.
• Dynamic changes in EV PD-L1 expression correlated with clinical outcomes.
• A post-treatment decrease in EpCAM+ EV PD-L1 was significantly associated with improved 5-year progression-free and overall survival.

Conclusions:

• EpCAM+ EV PD-L1 serves as a dynamic, non-invasive biomarker for monitoring immunotherapy response.
• SERS-based profiling of EVs can predict long-term responses to immune checkpoint blockade.
• This approach holds promise for personalized cancer treatment strategies.