CD8A and neoplasm: At the same time, PEI‐modification on detached OVs could increase the uptake of OVs by tumor cells and enhance the transfection effect of OVs in tumor cells, thus greatly improving the anti‐tumor efficacy of OVs and promoting the tumor immune microenvironment, including tumor lysis, tumor cytotoxicity and the increase in the amount of CD4+, CD8+ T cells, and DCs.