In current studies, epigenetic regulatory drugs including DNA methyltransferase inhibitors, histone deacetylase inhibitors, histone methyltransferase inhibitors, BET inhibitors, and non-coding RNAs can affect the oncogenic signaling in the cancer cells, and the resistance induced by those belongs to the primary resistance [73, 82, 97, 99]. Here, PRDM9 is linked to cancer.