Discovery of Potent and Orally Bioavailable Diaminoquinazoline-Derived mRNA Decapping Scavenger (DcpS) Enzyme Inhibitors for Treatment of Solid Tumors.

Decapping Scavenger (DcpS) enzyme, a pyrophosphatase involved in mRNA regulation via mRNA cap degradation, has been identified as a promising oncology target in fragile histidine triad (FHIT) deficient cancers such as AML and GBM but remains underexplored in broader solid tumor indications. We have discovered a novel DcpS inhibitor, compound 17, which has a differentiated binding mode relative to known inhibitors, engaging the second nucleotide-binding domain of the mRNA cap substrate. Compound 17 possesses superior levels of potency in NSCLC A549 cell line relative to known inhibitors and demonstrates excellent selectivity against DcpS-insensitive cell lines, high levels of bioavailability in preclinical species, and mitigated hERG liabilities. Finally, compound 17 demonstrates oral dose-dependent efficacy in two solid tumor xenograft models, A253 and EBC-1, highlighting the promise of DcpS as a novel target in FHIT low/deficient solid tumors.