T cells isolated from peripheral blood by leukapheresis can be genetically engineered in vitro to express modified TCRs that can be directed against specific tumor antigens, such as melanoma differentiation antigens and cancer/testis antigens (126); however, the downside of this TCR gene therapy remains its evasion by tumor cells, which can downregulate their major histocompatibility complex (MHC) expression (127). Here, HLA-C is linked to neoplasm.