CD8A and metastatic malignant neoplasm: In the current study, based on the transcriptomic profiles from the TCGA database, a multivariable Cox regression analysis was conducted to establish a novel four‐gene signature (CD8A, CD8B, TCF7, and LEF1), which serves as a biomarker of stem‐like CD8+ T cells and predicts the immune responses and clinical outcomes of patients with metastatic cancer prior to treatment.