Lead Identification of Novel Naphthyridine Derivatives as Potent SOS1 Inhibitors.

SOS1, a guanine nucleotide exchange factor (GEF), plays a critical role in catalyzing the conversion of KRAS from its GDP- to GTP-bound form, regardless of mutation status, and represents a promising new drug target to treat all KRAS-driven tumors. Herein, we employed a scaffold hopping strategy to design, synthesize, and optimize a series of novel binary ring derivatives as SOS1 inhibitors. Among them, compound (HH0043) displayed potent activities in both biochemical and cellular assays and favorable pharmacokinetic profiles. Oral administration of HH0043 resulted in a significant tumor inhibitory effect in a subcutaneous -mutated NCI-H358 (human lung cancer cell line) xenograft mouse model, and the tumor inhibitory effect of HH0043 was superior to that of BI-3406 at the same dose (total growth inhibition, TGI: 76% vs 49%). On the basis of these results, HH0043, with a novel 1,7-naphthyridine scaffold that is distinct from currently reported SOS1 inhibitors, is nominated as the lead compound for this discovery project.