Medical Health Encyclopedia

Immunnotoxins. Agents called immunotoxins use natural toxins to kill malignant brain cells.

Agents that employ diphtheria toxins, including TransMID-107R and DAB(389)EGF), are the first immunotoxins to show some promise. Clinical trials are investigating them for gliomas and metastatic brain cancers. Other toxins under investigation include irofulven (a mushroom toxin) and chlorotoxin (a substance derived from scorpions).

Taurolidine. Taurolidine is a unique agent that prevents tumor formation and growth in animals. An early clinical trial in patients with high-grade gliomas is under way.

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Protein-Blocking Drug. Another development is the discovery of a protein called BEHAB (Brain-Enriched Hyaluronan Binding Protein). BEHAB is produced only by invasive glioma tumor cells, not by normal brain tissue or noninvasive tumor cells. Breakdown of BEHAB releases a substance called HABD (hyaluronan-binding domain), which appears to give glioma cells the ability to invade other areas of the brain. Both BEHAB and HABD represent potential targets for new therapies.

Transplantation Procedures and High-Dose Chemotherapy

Chemotherapy destroys not only cancer cells, but also healthy cells, including special blood cells in the bone marrow called stem cells, which are immature cells from which all blood cells develop. Transplantation procedures using bone marrow or stem cells allow high-dose chemotherapy to be administered while protecting blood cells. The procedures are being tested for patients with brain tumors that are responsive to the effects of chemotherapy. A 2003 study, for example, reported long-term survival in some patients, but it is not clear if such rates are any better than other treatments. The procedure has serious, sometimes life-threatening, side effects.

Photodynamic Therapy

Photodynamic therapy employs a special agent (Photofrin) that is absorbed by the tumor and causes the cancer cells to become fluorescent when a laser is directed at them. It is being investigated in late-stage trials in combination with other treatments. A 2003 study reported encouraging results, notably with patients with recurring glioblastoma multiforme. In the study, more than half of these patients survived for at least a year.