Tumor-Infiltrating Lymphocytes in Melanoma Prognosis

Tumour-infiltrating lymphocytes (TILs) represent a key facet of the host immune response within the melanoma microenvironment. Their density, localisation and phenotypic composition furnish important prognostic information beyond conventional staging. High levels of cytotoxic T cells within the tumour parenchyma have consistently been linked to prolonged relapse-free and overall survival, while regulatory subsets may temper antitumour immunity. Spatial patterns of infiltration—whether lymphocytes are excluded to the stroma, diffusely present or aggregated in organised tertiary lymphoid structures—further refine risk stratification. Advances in digital pathology, gene-expression profiling and automated image analysis have standardised TIL assessment, transforming a once qualitative evaluation into a reproducible biomarker. In parallel, TIL quantification is emerging as a predictor of response to immune checkpoint inhibitors, guiding therapeutic decision making and identifying patients most likely to derive durable benefit from immunotherapy. Collectively, TIL evaluation in melanoma illustrates how immune contexture integrates with tumour biology to inform prognosis and tailor treatment.

Research from Nature Portfolio

Recent studies have employed multiplex immunohistochemistry to map the immune landscape of metastatic melanoma, distinguishing intratumoral and stromal lymphocyte subsets alongside checkpoint ligand expression. This approach has defined tumour immune context into categories reflecting degrees of immune escape and provided a framework to interpret responses to checkpoint blockade. In parallel, an open-source algorithm for automated TIL scoring on routine haematoxylin and eosin sections has been validated across multiple cohorts. Higher algorithm-derived TIL scores were independently associated with improved disease-specific survival, underscoring the potential for standardised, widely accessible prognostic metrics.

Tumor-Infiltrating Lymphocytes in Melanoma Prognosis publication trend

The graph below shows the total number of articles in tumor-infiltrating lymphocytes in melanoma prognosis across all publications each year (not limited to Nature Index journals).

Technical terms

Tumour-infiltrating lymphocytes (TILs): Immune cells, primarily T cells, present within the tumour microenvironment that reflect host antitumour immunity.

Electronic TIL score (eTILs): A digital pathology-derived percentage measurement of lymphocyte density within tumour areas, used as a continuous and categorical prognostic indicator.

Immune checkpoint inhibition (ICI): Therapeutic blockade of inhibitory receptors (such as PD-1 or CTLA-4) on T cells to enhance antitumour immune responses.

Tertiary lymphoid structures (TLS): Ectopic lymphoid aggregates forming within tumours that resemble secondary lymphoid organs and are generally associated with favourable prognosis.

References

1. Deep learning-based scoring of tumour-infiltrating lymphocytes is prognostic in primary melanoma and predictive to PD-1 checkpoint inhibition in melanoma metastases. EBioMedicine (2023).
2. Tumor-infiltrating lymphocytes in melanoma: from prognostic assessment to therapeutic applications. Frontiers in Immunology (2024).
3. Defining Melanoma Immune Biomarkers—Desert, Excluded, and Inflamed Subtypes—Using a Gene Expression Classifier Reflecting Intratumoral Immune Response and Stromal Patterns. Biomolecules (2024).
4. Baseline tumor-infiltrating lymphocyte patterns and response to immune checkpoint inhibition in metastatic cutaneous melanoma. European Journal of Cancer (2024).
5. Multiplex immunohistochemistry accurately defines the immune context of metastatic melanoma. Scientific Reports (2018).
6. An open source automated tumor infiltrating lymphocyte algorithm for prognosis in melanoma. Nature Communications (2019).