Recently the Central Brain Tumor Registry of the United States estimated that 180,000 new brain tumors were diagnosed, and that over 350,000 individuals in the United States were living with a brain tumor. Further, the incidence of primary brain tumors appears to be increasing in adults, becoming more and more a cancer of the elderly.

The majority of these are tumors that have metastasized to the brain from the lung, breast, colon, kidney or skin, making cure for the patient's primary tumor difficult, if not impossible. The most prevalent form of adult primary brain tumors is collectively referred to as glioma, and the most common and devastating type of glioma is glioblastoma multiforme (GBM).

The median survival time for most patients with high-grade gliomas and metastatic brain tumors is on the order of months. Indeed, even with the best surgical, radiological and anti-tumor drug therapies currently available, long-term survival of patients with metastatic or GBM tumors is extremely rare.

The Current Standard of Clinical Care for Cancers of the Brain
It is striking to note that overall the prognosis and survival for patients with metastatic and primary malignant brain tumors has not changed significantly in over 40 years. Brain tumors in general are difficult to treat because of the complexities associated with removing cancerous cells from a background of normal brain tissue without introducing considerable neurological damage.

Conventional therapy for malignant glioma consists of complete resection of the tumor, followed by radiation and occasionally chemotherapy. Radiation is needed because surgical resection misses small populations of cells that have migrated from the primary tumor site. The blood-brain barrier prevents use of most chemotherapeutic agents, and those that are available often have unacceptable side effects. Unfortunately, post-surgical radiation therapy and chemotherapy provide only a minor improvement in the disease course and life expectancy of patients diagnosed with malignant glioma.

Therefore, new approaches that target malignant glioma and metastatic brain tumors are desperately needed if these tumors are going to be treated adequately in the future. Ideally, any such therapy should have the ability to specifically target tumor tissue both near and distant from the tumor bed without harmful effects on normal brain tissues.