DDX5 (p68) and UbE2T as emerging superior cancer therapeutic targets: dual molecular glue target degradation by FL118 for conquering difficult-to-treat cancers

Growing evidence has revealed that DEAD-box RNA helicase 5 (DDX5, also known as p68) and ubiquitin-conjugating enzyme E2T (UbE2T) are two emerging and highly promising cancer therapeutic targets. This article provides the first comprehensive review of the physical and functional relationship between these two cancer targets, further refining their therapeutic potentials in solid cancers. In addition, the consequences of simultaneously degrading DDX5 and UbE2T proteins by the small-molecule dual molecular glue degrader FL118 in difficult-to-treat advanced cancers are presented.Specifically, this article reviews: (1) the roles of DDX5 and UbE2T in diverse cancer DNA repair pathways; (2) the physical binding relationship and potential functional roles of DDX5 in topoisomerase regulation; (3) the involvement of DDX5 in EZH2- and NANOG-associated prostate cancer stem cell (PCSC)-driven neuroendocrine prostate cancer (NEPC), castration-resistant prostate cancer (CRPC), and metastatic CRPC (mCRPC); (4) the contributions of DDX5 and UbE2T to inflammatory and immune regulation within the tumor microenvironment (TME); (5) FL118 as a small-molecule dual molecular glue degrader selectively targeting both DDX5 and UbE2T; (6) the high efficacy of FL118 against multiple difficult-to-treat advanced and metastatic cancers, including advanced colorectal cancer (CRC), pancreatic ductal adenocarcinoma (PDAC), osteosarcoma, Ewing sarcoma, ovarian cancer, and glioma/glioblastoma; (7) the resistance of ABCG2-expressing cancer cells to common anticancer agents but not to FL118; (8) the favorable pharmacokinetic and toxicology profiles of FL118 in mice, rats, and dogs; (9) the distinct functions of DDX5 in normal tissues, cells, and organs versus cancer; and (10) FL118 as a drug platform enabling the development of novel analogs and derivatives.Based on this review, we conclude that DDX5 and UbE2T represent superior anticancer therapeutic targets, and that the high efficacy of FL118 against multiple difficult-to-treat cancers is attributable to its function as a bona fide small-molecule dual molecular glue degrader that physically targets and degrades both DDX5 and UbE2T. Strikingly, this activity is observed regardless of the expression status of ABC transporter proteins, ABCG2/BCRP, ABCB1/Pgp/MDR1, and/or ABCC1/MRP1 in cancer cells.