CCR5 and chordoma: Other examples of interactions between chordoma and the immune system are the above mentioned plastic macrophages that, via the ccl5/ccr5 axis, are recruited and polarized by chordoma to enhance the proliferation, invasion and migration capabilities of chordoma (136); galectin-9 that interacts with TIM3-positive TILs and that promotes cell apoptosis (141) and the expression of CTLA-4, a promising immune checkpoint inhibitor target that it is expressed by the TILs that are infiltrating chordoma (129).