LY345899 is a Folate analog and a potent inbhibitor of methylene tetrahydrofolate dehydrogenase1 (MTHFD1; DC301) and methylene tetrahydrofolate dehydrogenase2 (MTHFD2) with IC50 values of 96 nM and 663 nM, respectively. It significantly suppresses tumor growth and reduces tumor weight in CRC patient-derived xenograft models.