The response to ICIs is influenced by several factors, which can be monitored using various biomarkers, including degree of CD8 + T cell infiltration, tumor mutation burden, mismatch repair, and the expression of critical immune checkpoints (PD-1, PD-L1, CTLA-4, LAG-3, TIM3, and TIGIT). The gene discussed is CTLA4; the disease is neoplasm.