Angiogenesis inhibitors

A solid tumor cannot grow beyond a few millimeters, or spread, without its own blood supply, so cancer cells send out chemical signals — chiefly a protein called VEGF — that prompt nearby blood vessels to sprout new branches toward the tumor. Angiogenesis inhibitors interrupt this process at different points: some are monoclonal antibodies (such as bevacizumab) that bind VEGF itself so it cannot activate its receptor; others are small molecules (such as sunitinib or sorafenib) that block the receptor or the signaling proteins downstream of it. Starved of new vessels, the tumor grows more slowly. The NCI notes that these drugs tend to halt expansion rather than destroy the cancer, which is why treatment is usually long-term and frequently paired with chemotherapy or other drugs. Side effects reflect the role blood-vessel signaling also plays in healthy tissue: bleeding, blood clots, high blood pressure, impaired wound healing, and protein in the urine have been reported.