Abstract 5947: Discovery of ACE-47228211, a highly potent and selective SOS1 inhibitor

Abstract Dysregulation of receptor tyrosine kinase (RTKs) and KRAS signaling is the most frequent causes of cancer development and progression. SOS1 is one of the major guanine nucleotide exchange factors (GEFs) that facilitates the conversion of the inactive GDP-bound KRAS “off” state to the activated GTP-bound KRAS “on” state. SOS1 is therefore required for dysregulated RTKs, and wildtype and mutant KRAS proteins to drive cancer cells. In addition, SOS1 plays a crucial role in modulating the reactivation of the RAS/MAPK signaling upon the treatment of RAS/MEK/ERK inhibitors. Thus, blocking SOS1 and KRAS protein-protein interactions could be an effective strategy for targeting KRAS-MAPK driven cancers. Here, we report the discovery of a highly potent and orally bioavailable small molecule SOS1 inhibitor, ACE-47228211. This molecule has a unique novel scaffold. It exhibits an IC50 of 8. 5 nM in the SOS1-KrasG12D (GDP) exchange assay and 5. 0 nM in cellular ERK phosphorylation assay in H1957 cells. ACE-47228211 at 3 mg/kg (BID) demonstrated significant tumor growth inhibition in MiaPaca-2 KRAS G12C tumor model than MRTX0920 at 50 mg/kg (BID). When combined with Sotorasib (5 mg/kg QD), a Kras G12C inhibitor, ACE-47228211 at 3 mg/kg exhibited synergistic effect similar to MRTX0920 at 50 mg/kg. Further, ACE-47228211 demonstrated synergistic effects with EGFR and FGFR2 inhibitors in RTK mutant tumor models. ACE-47228211 has excellent ADME and physical properties with low risks of hERG, CYP inhibition and drug-drug interactions. The evaluation of ACE-47228211 in a safety panel of 87 targets and a kinase panel of 500 targets shows that this molecule has favorable selectivity and safety profiles. The molecule is currently in IND enabling stage of development. Citation Format: Junmei Wang, Wenqian Li, Sanjeev Kumar, Weitao Pan, Zhiming Wen, Tinggui Yin, Genshi Zhao, Kuo-Long Yu. Discovery of ACE-47228211, a highly potent and selective SOS1 inhibitor abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 5947.