Discovery of Elironrasib (RMC-6291), a Potent and Orally Bioavailable, RAS(ON) G12C-Selective, Covalent Tricomplex Inhibitor for the Treatment of Patients with RAS G12C-Addicted Cancers

The discovery of elironrasib (RMC-6291) represents a
significant
breakthrough in targeting the previously deemed undruggable GTP-bound,
active KRASG12C. To target the active state of RAS (RAS(ON))
directly, we have employed an innovative tri-complex inhibitor (TCI)
modality involving formation of a complex with an inhibitor, the intracellular
chaperone protein CypA, and the target protein KRASG12C in its GTP-bound form. The resulting tri-complex inhibits oncogenic
signaling, inducing tumor regressions across various preclinical models
of KRASG12C mutant human cancers. Here we report structure-guided
medicinal chemistry efforts that led to the discovery of elironrasib,
a potent, orally bioavailable, RAS(ON) G12C-selective, covalent, tri-complex
inhibitor. The investigational agent elironrasib is currently undergoing
phase 1 clinical trials (NCT05462717, NCT06128551, NCT06162221), with
preliminary data indicating clinical activity in patients who had
progressed on first-generation inactive state-selective KRASG12C inhibitors.