At present, these mechanisms are thought to include DNA damage repair, such as source chromosome recombination repair, O6-methylguanine-DNA-methyltransferase (MGMT) repair; ectopic expression of multi-drug resistance related proteins (MRPs); abnormal apoptosis pathways; the presence of tumor stem cells; and changes in tumor immune microenvironment, like increased protective autophagy and non-folding protein reactions7,8. Here, MGMT is linked to neoplasm.