To understand the synergistic mechanism of Trabectedin and PD-1 blockade in the ID8 tumor model, we evaluated the composition of tumor-associated immune cells (TIC) in peritoneal lavage of treated mice 7 days after treatment commence, focusing on antitumor effector CD4+FoxP3- and CD8+ T cells and immunosuppressive CD11b+GR-1+ MDSC and CD4+FoxP3+ regulatory T cells (Treg). This evidence concerns the gene CD4 and neoplasm.