In addition, the introduction of checkpoint inhibitors (e.g., antibodies against PD‐L1 (programmed cell death-ligand 1), antibodies against CTLA-4 (cytotoxic T lymphocyte-associated antigen-4), small molecule IDO inhibitors (indoleamine 2,3-dioxygenase)) after phototherapy has been shown to markedly improve treatment efficacy by blocking the immunosuppressive receptors on the cell surface, thereby restoring the cytotoxic function of tumor-specific T-cells 28, 29. This evidence concerns the gene CTLA4 and neoplasm.