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Promise and Progress - One Physician's Quest for a Treatment for the Worst Kind of Pediatric Brain Tumor

Faces of Childhood Cancer

One Physician's Quest for a Treatment for the Worst Kind of Pediatric Brain Tumor

Date: June 1, 2004

One of the more difficult aspects of Ken Cohen’s job as director of pediatric neuro-oncology is telling parents that their child has a brain stem glioma. Cells from these cancerous tumors invade a portion of the brain called the pons. “Surgery isn’t an option because you can’t live without your pons,” says Cohen. “Parents come to me with what looks like a perfectly healthy child, and within six months they’re gone,” he says. “We just haven’t come close to getting a handle on these tumors.”

With the explosion of genetic discoveries and resulting new therapeutics in recent years, one would think researchers could come up with something to benefit these young patients. A testament to this is the telephone calls Cohen receives from parents all over the country whose children have been diagnosed with brain stem gliomas. “They call us because we’re Johns Hopkins, and surely we must have something that works. I have to tell them we don’t,” he says.

While there have been plenty of new drugs to hit the market, which one to try often comes down to a pie-in-the-sky approach. A chart hangs on the wall of his office displaying a long list of drugs and the various mechanisms by which they might work on this tumor—might being the key word. “We would like to select a drug based on rational research results.” Cohen says. “But, while there has been a lot of research on these tumors, it has been difficult to create a laboratory model. The cells die too easily in culture, and even when laboratory and animal models are successful, too often they don’t work in humans.” Added to these hurdles is the brain’s own physiology, the blood-brain barrier, which works against medicine. This biological phenomenon is typically a useful protective property that shields the brain from toxins and other invaders, but in cancer, it is a detriment, potentially preventing certain anticancer drugs from getting to the tumor cells.

Now, however, for the first time in years, Cohen is excited about a new therapy he’s developed and is now making available to Kimmel Cancer Center patients. The key element in his new therapy is, of all things, the poison arsenic. “Arsenic has been used successfully for many years to treat certain types of leukemia. It may directly poison abnormal glial cells of the brain, the same cells affected by brain stem gliomas, as well as working in combination with radiation therapy.” says Cohen. Cohen is hopeful that this new therapy may work against this relentless tumor.

Patients will receive a combined therapy of intravenous treatments and daily radiation treatments. Radiation therapy has had limited success against these tumors. “We think the arsenic will get the hypoxic, or oxygen-deficient, areas of the tumor, areas where radiation therapy does not work as well,” says Cohen.

His outlook is one of guarded optimism. This new therapy is backed by some good science, but he also realizes that this has been a resistant tumor where nothing he has tried before has worked particularly well. He says, “I hope this is the one that allows me to tell the parents that call me, Yes, I think we have something that will help your child.”

For more information on the arsenic trial in pediatric brain stem gliomas, contact Leslie Aronson, R.N., at 410-955-7349.