PARP1/BRD4-IN-3 (compound HF4) is an effective inhibitor of BRD4 and PARP1, with IC50 values of 1210 nM and 2019 nM respectively. The compound exhibits antiproliferative activity, induces apoptosis (apoptosis) and cell cycle arrest at the G0/G1 phase. Additionally, PARP1/BRD4-IN-3 causes DNA damage and reduces the expression of the Rad51 protein, demonstrating anti-tumor activity.