Commonly used predictive parameters for immunotherapeutic efficacy are PD-L1 expression (Powles et al., 2014), tumor mutational burden (TMB) (Snyder et al., 2014), microsatellite instability (MSI) (Dudley et al., 2016), and CD8 T cells (Ghatalia and Plimack, 2019). The gene discussed is CD8A; the disease is neoplasm.