Characterization of PD-L1 expression and immune cell infiltration in nasopharyngeal cancer
Oscar Siu Hong Chan1, Marcin Kowanetz2, Wai Tong Ng1
1Department of Clinical Oncology, Pamela Youde Nethersole Eastern Hospital, 3 Lok Man Road, Chai Wan, Hong Kong.
Objectives:
Locally recurrent or metastatic nasopharyngeal cancer (NPC) remains an important challenge, with more effective and durable therapeutic options needed. Cancer immunotherapy, and in particular therapies that target the PD-L1/PD-1 immune checkpoint pathway, may provide new options to treat NPC patients. This study evaluated PD-L1 and CD8 expression levels and the respective associations with clinical and histopathological characteristics of patients with NPC.
Materials And Methods:
Diagnostic tumour biopsies were obtained before radical radiotherapy with or without chemotherapy from 161 patients with NPC. These biopsies were analysed for PD-L1 expression levels on tumour cells (TC) and tumour-infiltrating immune cells (IC), and for CD8 T-cell infiltration. Results were correlated with baseline characteristics and clinical outcomes with standard-of-care treatment regimens. Additionally, pre- and post-treatment-paired tumour samples were analysed (n=146).
Results:
75% of tumours expressed PD-L1 on IC and 24% on TC. Baseline clinical characteristics of stage, sex and age did not correlate with PD-L1 expression. Additionally, overall survival and progression-free survival of standard-of-care treatment did not correlate with baseline PD-L1 expression. CD8 levels did correlate with clinical outcomes; however, results were confounded by other baseline characteristics. After treatment, PD-L1 expression dropped a median of 1.5% on IC and a median of 2.75% on TC. Median CD8 expression dropped 1.9%.
Conclusions:
Majority of NPC biopsy samples demonstrated PD-L1 expression on ⩾1% of IC, with fewer expressing PD-L1 on TC. In contrast to previous smaller studies, no prognostic value was observed for PD-L1 expression levels in patients with NPC.
Insights
This study found that while most nasopharyngeal cancer (NPC) tumors express PD-L1, its levels did not predict patient outcomes. CD8 T-cell levels showed correlation but were confounded by other factors.
Area of Science:
- Oncology
- Immunotherapy
- Cancer Research
Background:
- Locally recurrent or metastatic nasopharyngeal cancer (NPC) presents a significant therapeutic challenge.
- Cancer immunotherapy, particularly targeting the PD-L1/PD-1 immune checkpoint pathway, offers potential treatment avenues for NPC.
- Effective and durable treatment options for NPC patients are urgently needed.
Purpose of the Study:
- To evaluate PD-L1 and CD8 expression levels in NPC.
- To assess the association of PD-L1 and CD8 expression with clinical and histopathological characteristics.
- To determine the prognostic value of PD-L1 in NPC patients.
Main Methods:
- Analysis of diagnostic tumor biopsies from 161 NPC patients before radiotherapy.
- Assessment of PD-L1 expression on tumor cells (TC) and immune cells (IC), and CD8 T-cell infiltration.
- Correlation of expression levels with baseline characteristics, clinical outcomes, and post-treatment samples.
Main Results:
- 75% of tumors expressed PD-L1 on IC, and 24% on TC.
- No correlation was found between baseline PD-L1 expression and clinical characteristics or survival outcomes.
- CD8 levels correlated with outcomes but were confounded by other factors; PD-L1 and CD8 expression decreased post-treatment.
Conclusions:
- Most NPC biopsy samples showed PD-L1 expression on immune cells (IC), with fewer on tumor cells (TC).
- Unlike some smaller studies, this research found no prognostic value for PD-L1 expression levels in NPC patients.
- Further research may be needed to clarify the role of immune markers in NPC treatment.
