RM-055 is a novel catalytic RAS(ON) inhibitor that mimics endogenous GAP activity by accelerating GTP hydrolysis and converting active RAS(ON) to inactive RAS(OFF). Through formation of a non-covalent complex with cyclophilin A (CYPA), RM-055 efficiently suppresses oncogenic RAS signaling and demonstrates potent, durable antitumor activity in multiple G12-mutant cancer models.