MGMT and central nervous system cancer: Future efforts can be devoted to investigating the infiltration of M2 macrophages and the source of these cells based on gliomas of other molecular classifications (such as IDH mutation, promoter methylation of MGMT, chromosomal deletion of 1p/19q, B-RAF fusion, and point mutation), which can provide guidelines for more rational and precise utilization of our CCA-M1EVs in the treatment of GBM.