This is a first-in-human, phase 1, open-label, multicenter clinical trial designed to evaluate safety, tolerability, pharmacokinetics, biomarkers, pharmacodynamics and preliminary activity of orally administered KST-6051. The trial seeks to enroll adults with advanced or metastatic KRAS mutant solid tumors including but not limited to pancreatic ductal adenocarcinoma, colorectal cancer, and non-small cell lung cancer whose cancers have progressed after prior therapy or in whom standard therapy was not tolerated. The trial includes a dose escalation phase in which higher doses of KST-6051 will be given in subsequent groups of participants. Participants can stay in the trial as long as they benefit from the treatment and can tolerate it.