TOP1 and cancer: Schlafen 11 (SLFN11) is an emerging factor in cancer chemotherapy as it sensitizes cancer cells to a broad range of DNA-damaging anticancer agents causing replication stress, such as topoisomerase I (TOP1) inhibitors (camptothecin, indenoisoquinolines), TOP2 inhibitors (etoposide, doxorubicin), ribonucleotides inhibitors (hydroxyurea), antimetabolites (gemcitabine, cytosine arabinoside) and platinum-derivatives (cisplatin, carboplatin) [19–22].