As well as a viable treatment, the discovery could also opens the door to the development of a screening process that can identify patients for treatment strategies as well as becoming a useful diagnostic marker.
The treatment developed is based on the discovery of an unusual feature of the cells of glioblastomas - the least curable of all human cancers. The majority of the 17,500 US cases diagnosed each year are glioblastomas of which are particularly aggressive. Patients have a median survival time of nine to 12 months and a five-year survival rate of 1 to 5 five per cent.
Researchers found that glioblastoma cells have a type of receptor for interleukin 13 (IL 13), an immune regulating protein found in the body. Normal cells do not have these same receptors. The researchers developed a drug that combines a form of IL 13 with a toxin that kills cancer cells. By targeting the therapy to these receptors, the drug finds and kills the cancer cells.
Waldemar Debinski, lead researcher of the study, which took place at Wake Forest University Baptist Medical Centre, said: "We want to examine opportunities to take full advantage of the unique presence of restricted IL 13 receptors in glioblastomas as a treatment target."
"Maybe there is a better agent than IL 13 itself," he added. "Nature is great, but not perfect. Sometimes, we can make it even better for the benefit of our patients."
Debinski recently received a five-year, $1.25 million ((€950,000) grant from the National Cancer Institute to continue his studies IL 13, with the next step to re-engineer the protein so that it recognises cancer cells and completely spares normal tissues, something that cannot be achieved with normal chemotherapy.
Debinski additionally hopes to identify other agents that bind to the IL 13 receptors. If they are able to find agents smaller than IL 13, more opportunities to deliver treatment to cancer cells will arise.
Other goals are to design tests to assist in drug development, so researchers can determine which potential drugs will be most beneficial in patients, and to learn if combining radiation therapy with drug therapy will improve results. Researchers also hope to learn how to not only deliver the drugs to cancer cells, but also to direct the movement of the drug within these cells.
Debinki's findings may eventually benefit patients with other types of cancer. The researchers have observed that some other cancers have the same IL 13 receptors found in glioblastomas.
Brain tumours constitute a heterogeneous group of diseases that vary from benign, slow-growing lesions to aggressive malignancies that can cause death within a matter of months if left untreated. In addition to surgery, therapy includes irradiation, chemotherapy, or treatment with investigational approaches.
Researchers from the US and Europe are recognizing the need for new therapy that reduces toxicity and increases efficacy. Protein Kinases, as a drug target to fight cancer, promise much in terms of effectiveness and pharmaceutical efficacy.
One popular target is protein kinase inhibitors (PKI) of which many of the major drug companies are in the process of launching or have recently launched PKI drugs.
Chiron's Angiozyme, OSI's Tarceva (erlotinib), and Aventis' Flavopiridol (FP) demonstrated synergistic effects for many of these agents when combined with either chemotherapy or radiotherapy, leading to great enthusiasm regarding their ultimate contribution to cancer therapy. In order to be fully efficient, several PKI often have to be used in combinatory treatment regimes.
Worldwide, approximately 176,000 new cases of brain and other CNS tumours were diagnosed in the year 2003, with an estimated mortality of 128,000.