In a proof-of-concept study, Maneiro et al. developed a specific trastuzumab-PROTAC conjugate, which would selectively bind to HER2 receptors on tumor cells and induce endosomal internalization and the release of the PROTAC, which would then selectively target and degrade the bromodomain-containing protein 4 (BRD4—an attractive oncogenic target with a role in transcriptional dysregulation) [191]. This evidence concerns the gene BRD4 and neoplasm.