Targeted Drug Therapy
Targeted drug therapy uses drugs that take advantage of the differences between cancer cells and normal cells.
By targeting the differences that allow tumor cells to grow rapidly, this new class of drugs can slow or block the growth of tumors by interfering with molecules or cellular processes that are unique to tumors.
Targeted drug therapy is increasingly used to treat brain tumors. Typically, it is used alongside a combination of surgery, chemotherapy, and radiation therapy, particularly for patients with recurrent tumors.
Unlike standard chemotherapy drugs, which typically target dividing cells and cannot distinguish between healthy or cancerous cells, targeted drug therapy interferes with specific molecular pathways that are altered in cancer cells. This means that these drugs usually do not have the same side effects as those seen with chemotherapy.
While research is ongoing to identify suitable targets for specific cancers, there are several basic strategies for developing a targeted drug therapy. Targeted drug therapies that are currently approved for brain tumors include the following:
Angiogenesis is the growth of new blood vessels, a critical step during the growth of aggressive brain tumors. Brain tumors must have a suitable blood supply to deliver the necessary oxygen and nutrients that tumor cells need for continued growth. Angiogenesis inhibitors (or anti-angiogenic drugs) can slow tumor growth by interfering with blood vessel formation and growth.
For example, bevacizumab (also called Avastin) is an anti-angiogenic drug that slows tumor growth, and is currently approved for use in recurrent glioblastoma.
Signal transduction is the process through which cells respond to cues in the environment. For example, certain molecules can bind to proteins on the surface of a cell, causing a chain reaction of biochemical events (through a signaling pathway) that can affect whether a cell grows and divides. By interfering with components of specific signaling pathways, signal transduction inhibitors can block cellular processes that are critical for tumor growth and survival.
For example, Everolimus (also called Afinitor) is a signal transduction inhibitor that blocks mTOR, a protein involved in cell growth, proliferation, and survival. This drug is currently approved for use in adults and children with subependymal giant cell astrocytoma, specifically those with a diagnosis of tuberous sclerosis and a tumor(s) that is inoperable.
Additional strategies for targeted drug therapies have been successful in treating other cancers, and ongoing research is being done to identify and test targeted drug therapies for brain tumors.