[PD-L1 expression: An emerging biomarker in non-small cell lung cancer]

Area of Science:

• Oncology
• Immunology
• Biomarker Research

Background:

• Immune checkpoint inhibitors targeting programmed death 1 (PD-1) and programmed death ligand 1 (PD-L1) represent a significant advancement in treating various cancers, including metastatic non-small cell lung cancer (NSCLC).
• The clinical utility of these therapies necessitates the identification of reliable predictive biomarkers to guide treatment decisions, optimize efficacy, and manage costs and adverse events.

Purpose of the Study:

• To evaluate the role of programmed death ligand 1 (PD-L1) expression as a predictive biomarker for response to immune checkpoint inhibitors in non-small cell lung cancer (NSCLC).
• To highlight the challenges and future directions in standardizing PD-L1 testing methodologies for clinical application.

Main Methods:

• Review of clinical trial data associating PD-L1 expression, assessed by immunohistochemistry (IHC), with response rates and survival outcomes in patients treated with anti-PD-1 and anti-PD-L1 therapies.
• Analysis of methodological variations in PD-L1 IHC assays, including primary antibodies and scoring algorithms, and their impact on results.

Main Results:

• PD-L1 expression detected by IHC has shown correlation with improved response rates and overall survival in patients with NSCLC receiving immune checkpoint inhibitors.
• Significant heterogeneity exists in PD-L1 assay methodologies and tumor expression patterns, posing challenges for consistent patient selection.

Conclusions:

• PD-L1 expression is a promising but imperfect predictive biomarker for guiding immune checkpoint inhibitor therapy in NSCLC.
• Standardization and harmonization of PD-L1 testing assays are essential. Future strategies may involve combining PD-L1 assessment with other tumor immune microenvironment markers for more accurate patient stratification.