CD8A and neoplasm: Tumor-infiltrating CD8+ T cells express many inhibitory receptors, including PD- 1, B-, and T-lymphocyte attenuator, mucin domain-3 (TIM-3), lymphocyte-activation gene 3 protein (LAG-3), T-cell immunoglobulin domain, and the newly demonstrated T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT), to maintain the balance of immune response.