SETDB1-TTD-IN-1 is a potent and selective inhibitor of the SETDB1 tandem tudor domain (TTD), exhibiting high affinity with a Kd of 88 nM. This compound serves as a valuable chemical probe for investigating the role of SETDB1 in epigenetic regulation, facilitating both in vitro biochemical and cellular studies of its function in oncology and neurobiology research.