Medical Health Encyclopedia

Tumor Vaccines. Tumor vaccines are also being created, in which tumor cells are removed from the patient and inactivated; when they are transferred back to the patient, they are harmless but can elicit a powerful immunologic response against the tumor. For example, a vaccine that combines tumor proteins with the patient's nerve cells is being tested in astrocytomas.

Cell Growth and Angiogenesis Inhibitors

Much research is focusing on drugs that block small molecules involved with the growth of blood vessels that feed the tumor (a process called angiogenesis). Such agents, when effective, would starve tumors of vital nutrients and oxygen.Angiogenesis is particularly important in the growth of glioblastomas, the most malignant brain tumors. Of particular promise are agents that inhibit enzymes called tyrosine kinase, farnesyl protein transferase, and matrix metalloproteinase, which play critical roles in angiogenesis.

Farnesyl Protein Transferase Inhibitors. Farnesyl protein transferase inhibitors, such as tipifarnib, also called R115777 (Zarnestra) and lonafarnib (Sarasar), are drugs in a new class that block a mutated gene called the Ras gene, which is responsible for about 30% of cancers. Lonafarnib is in early trials in combination with temozolomide. Tipifarnib is also currently in early trials and may prove be effective as radiosensitizer.

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Tyrosine Kinase Inhibitors. Drugs that target growth factors receptors such as tyrosine kinase, interfere with the pathway leading to angiogenesis. Some tyrosine kinase inhibitors, including erlotinib (Tarceva), imatinib (Gleevac), gefitinib (Iressa), and others are being investigated in early trials for brain tumor treatment. Side effects include rash, diarrhea, nausea and vomiting. Some of these drugs may reduce white blood cell count or cause liver damage. Researchers are trying to identify biomarkers that could help predict which patients would best respond to tyrosine kinase inhibitor therapy.