From Micromolar to Nanomolar: A First-in-Class B3GAT3 Inhibitor Emerges for Liver Cancer
- B3GAT3 (beta-1,3-glucuronosyltransferase) is overexpressed in hepatocellular carcinoma (HCC) and correlates with poor patient prognosis, marking it as a promising but previously untargeted anti-cancer target.
- The research team started from TMLB-C16, an in-house lead compound with micromolar-range inhibitory potency against B3GAT3.
- Using structure-guided design, they synthesized 60 novel derivatives built on a 6-methoxyquinoline-4-carboxamide scaffold, systematically probing structure-activity relationships (SAR).
- This optimization campaign identified TMLB-G9, a candidate whose potency improved dramatically, moving from the micromolar starting point to nanomolar activity.
- TMLB-G9 is reported as a first-in-class B3GAT3 inhibitor, offering a new chemical starting point for potential HCC drug development.
Glycosyltransferases have a reputation for being nearly undruggable — shallow, solvent-exposed active sites built to grip a UDP-sugar donor and a growing acceptor chain, not a cozy pocket for a small molecule. So any inhibitor reaching nanomolar here deserves a second look. 60 analogs to go from micromolar to nanomolar on one scaffold is a lean, efficient campaign — a couple of hot spots optimized, not a fishing expedition. The 6-methoxyquinoline-4-carboxamide is flat and stackable, which reads like it's wedging into a groove near the sugar-binding cleft rather than mimicking the full UDP-GlcA donor. My real worry is the B3GAT family — B3GAT1/2/3 share a fold, and no selectivity data has been shown yet. First-in-class glycosyltransferase inhibitors are still rare in oncology, so this is a genuine new tool, but 'first-in-class' this early just means untested against the paralogs that matter.