Development of DCL1191 as a Potent, Selective and Orally Bioavailable Inhibitor for Autophagy-Associated Transcription Factor EB (TFEB).

Transcription factor EB (TFEB) is a promising target for autophagy regulation and cancer therapy, yet it has long been regarded as an undruggable protein. Starting from eltrombopag, an FDA-approved agent that exhibits both thrombopoietin receptor (Tpo-R) agonistic activity and TFEB inhibitory potency, we performed systematic structure-activity relationship optimization and identified DCL1191 as a potent, selective, and orally bioavailable TFEB inhibitor. DCL1191 binds TFEB with a Kd of 80.5 nM and disrupts the TFEB-DNA interaction with an IC50 of 60.5 nM. Computational modeling combined with site-directed mutagenesis elucidated its precise binding mode. DCL1191 exhibits diminished activity toward Tpo-R and MITF. Mechanistically, DCL1191 effectively represses the transcription of TFEB target genes and blocks intracellular autophagic flux. In autophagy-hyperactivated U87 glioblastoma cells, DCL1191 substantially sensitizes tumor cells to temozolomide chemotherapy. Pharmacokinetic evaluation in rats further demonstrated that DCL1191 possesses an i.v. half-life of 16.33 h and satisfactory oral bioavailability of 18.77%.