KDM1A and neoplasm: DNMTi 5-azacytidine in combination with other types of cancer drugs, such as romidepsin, gemcitabine, venetoclax, LSD1 inhibitor, temozolomide, and isocitrate dehydrogenase-1 (IDH1) inhibitor, increases the treatment effect, indicating that the key molecules regulating ERVs are expected to become tumor treatment targets and may even be used in combination with existing anticancer drugs (Fig. 1).