Design, Synthesis,\nand Activity Evaluation of BRD4\nPROTAC Based on Alkenyl Oxindole-DCAF11 Pair

Proteolytic targeting chimera (PROTAC) represent an advanced\nstrategy\nfor targeting undruggable proteins, and the molecular warheads targeting\nE3 ligases play a crucial role. Recently, we explored an alkenyl oxindole\nwarhead targeting the E3 ligase DCAF11 and sought to validate its\npotential. In this study, we synthesized a range of BRD4 PROTACs (<b>8a</b>–<b>8o</b>, <b>14a–14f</b>, <b>22a–22m</b>) with modified alkenyl oxindole warheads and\ndeveloped a high-throughput screening system based on high-content\nimaging. We identified <b>L134</b> (<b>22a</b>) as a potent\nBRD4 degrader, achieving BRD4 degradation (<i>D</i><sub>max</sub> > 98%, DC<sub>50</sub> = 7.36 nM) and demonstrating\nantitumor\nactivity. Mechanically, BRD4 degradation by <b>L134</b> was\nmediated through the ubiquitin-proteasome system in a DCAF11-dependent\nmanner. Therefore, this study provides a rapid screening method for\neffective PROTACs and highlights the PROTAC <b>L134</b> based\non alkenyl oxindole-DCAF11 pair as a promising candidate for treating\nBRD4-driven cancers.