Genetic and pharmacologic evidence has shown that SHP2, a non-receptor protein tyrosine phosphatase (PTP) and scaffold protein encoded by the PTPN11 gene, is a convergent signal transduction node that integrates growth factor signals from multiple receptors to promote activation of RAS and its downstream effectors. Guided by structural insights from X-ray data, we describe a strategy aimed at the identification of a highly potent and selective allosteric SHP2 inhibitor series. Our efforts led to the discovery of RMC-4550, a potent and selective SHP2 inhibitor which exhibits a high quality, drug-like preclinical profile. RMC-4550 inhibits purified, activated full length human SHP2 with an IC50 of 1.55 nM, and has cellular IC50 of 39 nM in PC9 cells with a pERK readout. RMC-4550 has no detectable inhibitory activity up to 10 µM against the catalytic domain of SHP2, a panel of 14 additional protein phosphatases, and a panel of 468 protein kinases. RMC-4550 exhibits low to moderate cross species in vitro intrinsic clearance (3.6-24 µL/min/million cells) in hepatocytes, a high passive permeability (458 nm/s) and efflux ratio of 1. The ADME properties translate into favorable pharmacokinetic profiles in preclinical species. RMC-4550 has moderate to high bioavailability and has a half-life amenable for once daily oral administration. In the EGFR-driven KYSE-520 human esophageal cancer xenograft model, we observed a dose dependent efficacy consistent with target modulation, assessed by phospho-ERK inhibition in tumors. RMC-4550 is well tolerated at doses that achieved maximal and sustained efficacy in this model. RMC-4550 was synthesized in 5 linear (6 total) steps from the readily accessible or commercially available intermediates. The chemical structure and synthesis of RMC-4550, along with detailed structure-activity relationships will be presented. In summary, RMC-4550 exemplifies a novel class of potent allosteric inhibitors of SHP2 with an excellent drug like property profile.
Citation Format: Elena S. Koltun, Naing Aay, Andreas Buckl, Ashutosh S. Jogalekar, Gert Kiss, Abby Marquez, Kevin T. Mellem, Kasia Mordec, Mae Saldajeno-Concar, Chris M. Semko, Nidhi Tibrewal, Christos Tzitzilonis, Walter Won, Jacqueline A. Smith, Susan E. Wilson, Robert J. Nichols, Zhengping Wang, David Wilds, Mallika Singh, Adrian L. Gill. RMC-4550, an allosteric inhibitor of SHP2: Synthesis, structure, and anti-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4878.