Four HDAC inhibitors (vorinostat, romidepsin, belinostat and panobinostat) have been approved by the FDA to treat cancer.98 In a recent systematic review, cancer patients treated with pan‐HDAC inhibitors exhibited mild cardiac side effects.106 Therefore, future work in this field is needed to delineate global cardiovascular safety of treatment with HDAC inhibitors in cancer patients. Here, HDAC9 is linked to cancer.