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Updated: Apr 16, 2026
Multiplexed Immunofluorescence Analysis and Quantification of Intratumoral PD-1+ Tim-3+ CD8+ T Cells
Published on: February 8, 2018
Characterization of PD-L1 Expression and Associated T-cell Infiltrates in Metastatic Melanoma Samples from Variable
Harriet M Kluger1, Christopher R Zito2, Meaghan L Barr3
1Department of Medicine, Yale University School of Medicine, New Haven, Connecticut. harriet.kluger@yale.edu.
Purpose:
Programmed death ligand-1 (PD-L1) tumor expression represents a mechanism of immune escape for melanoma cells. Drugs blocking PD-L1 or its receptor have shown unprecedented activity in melanoma, and our purpose was to characterize tumor PD-L1 expression and associated T-cell infiltration in metastatic melanomas.
Experimental Design:
We used a tissue microarray (TMA) consisting of two cores from 95 metastatic melanomas characterized for clinical stage, outcome, and anatomic site of disease. We assessed PD-L1 expression and tumor-infiltrating lymphocyte (TIL) content (total T cells and CD4/CD8 subsets) by quantitative immunofluorescence.
Results:
High PD-L1 expression was associated with improved survival (P = 0.02) and higher T-cell content (P = 0.0005). Higher T-cell content (total and CD8 cells) was independently associated with improved overall survival; PD-L1 expression was not independently prognostic. High TIL content in extracerebral metastases was associated with increased time to developing brain metastases (P = 0.03). Cerebral and dermal metastases had slightly lower PD-L1 expression than other sites, not statistically significant. Cerebral metastases had less T cells (P = 0.01).
Conclusions:
T-cell-infiltrated melanomas, particularly those with high CD8 T-cell content, are more likely to be associated with PD-L1 expression in tumor cells, an improved prognosis, and increased time to development of brain metastases. Studies of T-cell content and subsets should be incorporated into trials of PD-1/PD-L1 inhibitors to determine their predictive value. Furthermore, additional studies of anatomic sites with less PD-L1 expression and T-cell infiltrate are needed to determine if discordant responses to PD-1/PD-L1 inhibitors are seen at those sites.
Insights
High programmed death ligand-1 (PD-L1) expression in melanoma correlates with increased T-cell infiltration and better survival. This suggests T-cell content may predict response to PD-1/PD-L1 inhibitors.
Area of Science:
- Oncology
- Immunology
- Pathology
Background:
- Programmed death ligand-1 (PD-L1) expression is a key immune evasion strategy in melanoma.
- Therapies targeting PD-L1 or its receptor demonstrate significant efficacy in melanoma treatment.
- Understanding PD-L1 expression and T-cell infiltration is crucial for optimizing immunotherapy.
Purpose of the Study:
- To investigate the relationship between tumor PD-L1 expression and T-cell infiltration in metastatic melanoma.
- To assess the prognostic significance of PD-L1 expression and T-cell infiltration in melanoma patients.
Main Methods:
- Utilized a tissue microarray (TMA) from 95 metastatic melanoma patients.
- Assessed PD-L1 expression and tumor-infiltrating lymphocyte (TIL) content (total, CD4, CD8) via quantitative immunofluorescence.
- Correlated findings with clinical stage, outcome, and disease site.
Main Results:
- High PD-L1 expression was linked to improved survival (P=0.02) and greater T-cell infiltration (P=0.0005).
- Elevated T-cell content (total and CD8) independently predicted improved overall survival.
- High TIL content in extracerebral metastases correlated with a longer time to brain metastasis development (P=0.03).
Conclusions:
- Melanomas with high T-cell infiltration, especially CD8+ cells, show higher PD-L1 expression, better prognosis, and delayed brain metastasis.
- Incorporating T-cell subset analysis into trials of PD-1/PD-L1 inhibitors may reveal predictive value.
- Further research is needed to explore discordant responses at sites with lower PD-L1 and T-cell infiltration.
