In addition to TMB, the composition of the tumor immune microenvironment (TIME) is another determinant of the response to immunotherapy, such as immunosuppressive cells (regulatory T cells and myeloid-derived suppressor cells) and cytokines (PGE2, IDO1, TGF-β, IL-10, etc.)(Liu and Cao, 2016). Here, IDO1 is linked to neoplasm.