Targeted degradation of GSPT1 and NEK7 by a molecular glue prodrug for treatment of HCC

Abstract Targeted Protein Degradation (TPD) technology, in the form of CRBN-modulating molecular glues, offers numerous unprecedented therapeutic benefits as evidenced by the success of approved high-value immunomodulatory imide drugs (IMiDs) such as lenalidomide and pomalidomide. Building upon these successes, we employed a small CRBN-focused library of molecular glues in a phenotypic screen against hepatocellular carcinoma (HCC) cell lines. While the original library was primarily designed to target SALL4, we identified additional CRBN substrates, including GSPT1, NEK7, and CK1 α , whose degradation potently induced cell death in HCC cell lines. Subsequent lead optimization efforts yielded a compound, ABS-752, which demonstrated superior in vitro and in vivo activity through the potent degradation of GSPT1. Notably, ABS-752 does not form ternary complexes with CRBN and the neosubstrates. Further investigations revealed that ABS-752 is a prodrug activated by the monoamine oxidase, VAP-1, to an aldehyde intermediate and subsequently to the active molecule, ABT-002. VAP-1, which is overexpressed in cirrhotic liver, was identified as the primary monoamine oxidase responsible for the conversion of ABS-752. ABS-752 is currently in clinical trials for the treatment of HCC.