New drug CCT3833 elicits significant preclinical therapeutic efficacy in KRAS-mutant colorectal, lung and pancreatic tumor xenografts…CCT3833 inhibits KRAS-mutant cancer cell growth...CCT3833 is active against a panel of KRAS-mutant PDAC, CRC and NSCLC cell lines...CT3833 has been evaluated in a phase I clinical trial (NCT02437227) and we report here that it significantly prolongs progression-free survival of a patient with a G12VKRAS spindle cell sarcoma.