Furthermore, secretion of CCL2 (mainly by tumor-associated astrocytes (Liu et al., 2020)) in the BTME of MB was reported as responsible for leptomeningeal metastasis (Garzia et al., 2018), thus also promoting the recruitment of other immune cells, including those derived from the bone marrow-derived macrophages (Maximov et al., 2019). This evidence concerns the gene CCL2 and neoplasm.