PDCD1 and melanoma: In a recent report, RNA single-cell analysis of melanoma metastatic lesions led to the identification of TCF7+CD8+ T cells as a predictor of response to immunotherapy (anti-CTLA-4, anti-PD-1, or their combination), while higher expression of exhausted CD8+ T cell (LAG-3+ and TIM-3+) has been associated with ICI failure [111].