Can nose drops treat brain cancer?

Published on Thursday, 11 November 2010 14:33

By Jamese Hilliard

Brain tumors are one of the most lethal and difficult to treat types of cancer. Treatment is complicated by the inadequate delivery of antitumor drugs to the tumor.

Recently, scientists are reporting the development and successful initial testing of a new form of treatment designed to be given as nose drops rather than injected. It shows promise as a more effective treatment for brain cancer, they say. The report appears in ACS' Molecular Pharmaceutics, a bi-monthly journal. In studies conducted by Tomotaka Shingaki and colleagues, a nasal formulation evaluated using methotrexate as a model antitumor agent. Shingaki notes that in order to treat tumors efficiently, it is necessary to transport antitumor agents across the specialized vascular system of the brain. This protective layer of cells surrounding the brain (the so-called blood-brain barrier) prevents medication in the blood from entering the brain. New evidence indicates that some drugs administered through the nose, either as nose drops or nasal spray, can bypass this barrier and travel directly into the brain.

Scientists tested methotrexate nose drops on laboratory rats with brain cancer. When compared to cancer treated with an injectable form of the drug, the nose drop drug reduced the weight of tumors by almost one-third, the scientists said.

How does this treatment differ from current methods of treatment? According to the National Cancer Institute, there are three standard therapies for the treatment of brain cancer.

Surgery

Surgery is used to diagnose and treat adult brain tumors. However, even if all the cancer that can be seen at the time of the surgery is removed, some patients may be given chemotherapy or radiation therapy after surgery to kill any cancer cells that are left.

Radiation therapy

Radiation therapy uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type of tumor and where it is in the brain.

Chemotherapy

Chemotherapy uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body. To treat brain tumors, a dissolving wafer may be used to deliver an anticancer drug directly to the brain tumor site after the tumor has been removed by surgery. The way the chemotherapy is given depends on the type of tumor and where it is in the brain.

Other types of treatment are being tested in clinical trials include

Biologic therapy or immunotherapy which uses the patient’s immune system to fight cancer. Substances made by the body or made in a laboratory are used to boost, direct, or restore the body’s natural defenses against cancer.

Some of the advantages of nasal treatment are a reduction of delivery to nontargeted sites, administration of lower doses and, in turn, reduced toxicity. Long term toxicity of this type of delivery system are unknown, though side effects of methotrexate are often observed in the kidney. Since methotrexate is toxic to nontumor normal cells, repeated use of the drug is likely to change the nasal absorption and/or disposition of the drug.

Much work remains to evaluate this promising therapy, however according to Shingaki, "The strategy to utilize the nose-brain direct transport may be applicable to a new therapeutic system not only for brain tumors but also for other central nervous system disorders such as neurodegenerative diseases”.