Small-molecule RAS/RAF Binding Inhibitors Allosterically Disrupt RAF Conformation and Exert Efficacy Against a Broad Spectrum of RAS-driven Cancers

Abstract With the advent of approved subtype-specific RAS inhibitors targeting KRASG12C mutation, the development of RAS inhibitors effective regardless of RAS mutation status is the next major challenge to address clinically prevalent RAS mutations and further overcome RAS-driven acquired resistance to currently available drugs. Here our multi-module drug screening for compounds capable of RAS/RAF-binding inhibition, and subsequent structural study discovered small-molecule compounds which covalently bind to a unique site in the regulatory domain of RAF, and disrupt RAF conformation allosterically, thereby preventing RAS/RAF-interaction and downstream signals. The compounds exhibit anti-tumor efficacy to multiple cancer types with broad-spectrum RAS mutations including clinically predominant G12D and G12V KRAS, NRAS and HRAS in pre-clinical models. Furthermore, the compounds effectively suppress tumor growth of BRAFV600E-melanoma with acquired resistance to RAF kinase inhibitor. Collectively, our study provides effectiveness for designing RAF-targeting drugs, and potentially therapeutic RAS/RAF-signaling inhibitors with novel mechanism to overcome broad-range RAS-driven cancers.