Increased EGFR Phosphorylation Correlates with Higher Programmed Death Ligand-1 Expression: Analysis of TKI-Resistant...

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Immunotherapies targeting PD-1/PD-L1 are crucial for non-small cell lung cancer (NSCLC) treatment.
• Efficacy of these immunotherapies is reduced in NSCLC patients with epidermal growth factor receptor (EGFR) mutations.
• The molecular mechanisms behind this reduced efficacy remain unclear.

Purpose of the Study:

• To investigate programmed death ligand-1 (PD-L1) protein expression in EGFR-mutated NSCLC cell lines.
• To analyze the relationship between EGFR phosphorylation and PD-L1 expression during acquired resistance to EGFR tyrosine kinase inhibitors (TKIs).

Main Methods:

• Analysis of PD-L1 protein expression via immunohistochemistry in parental and EGFR-TKI resistant NSCLC cell lines with EGFR mutations.
• Assessment of EGFR phosphorylation status, T790M mutation, MET amplification, and EGFR loss in resistant cell lines.

Main Results:

• Parental EGFR-mutant NSCLC cell lines exhibited variable PD-L1 expression (negative to positive).
• Acquired resistance to EGFR-TKIs was associated with increased EGFR phosphorylation and elevated PD-L1 expression.
• Secondary T790M mutation accompanied increased EGFR phosphorylation and PD-L1 expression.
• MET amplification or EGFR loss in resistant cells correlated with decreased EGFR phosphorylation and PD-L1 expression.

Conclusions:

• EGFR-mutant NSCLC cell lines do not inherently express high levels of PD-L1.
• EGFR phosphorylation status significantly impacts PD-L1 expression, especially in the context of acquired resistance to EGFR-TKIs.
• These findings may offer insights into improving immunotherapy response in EGFR-mutant NSCLC.