PTC299 + exemestane

PTC299 + exemestane is a combination drug consisting of **PTC299**, a potent small molecule inhibitor of dihydroorotate dehydrogenase (DHODH), and **exemestane**, a steroidal aromatase inhibitor. PTC299 acts by inhibiting DHODH, leading to suppression of de novo pyrimidine nucleotide synthesis, which in turn inhibits vascular endothelial growth factor A (VEGFA) mRNA translation and decreases cell proliferation, particularly in hematologic and some solid tumors. Exemestane blocks the aromatase enzyme responsible for estrogen biosynthesis, resulting in decreased estrogen production and is primarily used for hormone-sensitive breast cancer. This combination targets two distinct biological pathways—nucleotide synthesis and estrogen signaling—for synergistic anti-tumor effects, and has been evaluated in clinical trials for the treatment of metastatic breast cancer[1][2][3].