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Pontine Glioma
June 2006
Glioma Research at Texas Children’s Cancer Center by Ching Lau, M.D., Ph.D.
The researchers at Texas Children’s Cancer Center, using the latest high throughput genomic technologies, have performed comprehensive genetic analysis of gliomas including diffuse brainstem gliomas. The initial findings indicate that high grade gliomas have much more genetic changes than low grade gliomas. In addition, a few cases of high grade glioma have similar mutations as those in adult cases, suggesting that there might be similar mechanisms underlying the formation of gliomas in children and adults. It was also noted in a limited number of cases that there was both loss of a copy of a potential oncogene and the amplification of the remaining copy of the same gene. This is possibly a novel mechanism of activation of a potential oncogene in human cancer. However, because of the limited number of diffuse brainstem glioma cases with tissue available for analysis, no definitive conclusions can be drawn regarding this particular type of brain tumor. These findings are now being submitted for publication.
An Update on Diffuse Pontine Glioma Treatment by Alison A. Bertuch, M.D., Ph.D.
Despite the numerous clinical trials performed over the past several decades, the prognosis for children with diffuse pontine glioma remains very poor and conventional radiation therapy remains the standard of care. Nevertheless, the pediatric neurooncology community remains undeterred, and has now turned to studying novel treatment approaches for diffuse pontine glioma in a variety of single institution and multi-institution clinical trials. For example, researchers at the National Cancer Institute are investigating the efficacy of PEG-Intron™, which may improve the body’s immune response to diffuse pontine gliomas. Investigators within the Children’s Oncology Group have recently studied the use of Temodar™, a drug that impairs the ability of tumor cells to repair damaged DNA, and which has shown some promise in adult brain tumors. Lastly, members of the Pediatric Brain Tumor Consortium are studying a number of agents in the treatment of diffuse pontine gliomas, including those that affect critical growth signaling pathways in tumors such as Iressa™. These are just three of several studies that are currently or have recently been open to enrollment for patients. There are more on the horizon. At any given time, one or more clinical trials for children with diffuse pontine glioma may be open, many which are available at institutions across the country. With perseverance, we hope that the future will bring us to a new standard of care that does not simply prolong survival but rather leads to long-term survivors.
December 2004
Pontine Glioma present one of the most formidable challenges to the field of pediatric oncology. These tumors arise in the region of the brain, called the brainstem, which is required for some of our most vital functions, such as breathing. Due to their highly aggressive nature, children with Pontine Glioma will have symptoms that progress rapidly in the period of time prior to their diagnosis. Symptoms may include abnormal eye movements and double vision, drooping of one side of the face, difficulty swallowing, weakness on one or both sides of the body, wobbly gait, or difficulty doing a number of activities of daily living such as getting dressed or brushing one’s teeth. In addition, a child with a Pontine glioma may experience headaches, vomiting, tiredness or lethargy, and/or a decline in their school performance.
In the United States, approximately 150-200 children are diagnosed yearly with brainstem glioma, with most being diagnosed during the first decade of life. Up to 75% of these children will have diffuse Pontine Glioma, which are highly infiltrative tumors involving a particular area of the brainstem called the pons. Tragically, these tumors carry the worst prognosis among the various subtypes of brainstem tumors; most children with diffuse Pontine Glioma will die between six months to two years from the time of diagnosis. Why is this? Because of their location in such a vital area of the brain and their infiltrative nature, diffuse Pontine Glioma are inoperable tumors. Therefore, surgery, which is essential for the cure of most brain tumors, is not an option for these children. Radiation therapy helps delay the progression of diffuse Pontine Glioma, but, unfortunately, is not curative. Lastly, despite intensive efforts over the years to identify effective drugs, all efforts have failed, as these tumors have proven highly resistant to conventional chemotherapy. Today, pediatric brain tumor researchers, like those in the Pediatric Brain Tumor Consortium and the Children’s Oncology Group, continue their quest for a cure for this deadly tumor by testing novel, state-of-the art therapies in experimental treatment trials.
Why a particular child develops a diffuse Pontine glioma is most often unknown. It is believed that these tumors arise when critical mutations incur in the DNA of a single cell in the pons, and these lead to uncontrolled and malignant cell growth. Understanding the exact genetic changes that result in diffuse Pontine glioma will no doubt aid in finding a cure, however, progress in this arena has been challenging as well. Unlike most other malignancies, because of the very critical region of the brain that is involved, and the very unique characteristics of these tumors when viewed by MRI, diffuse Pontine Glioma are biopsied infrequently. Consequently, only rarely do these tumors make their way to a research laboratory where they can be studied. Undaunted, families and pediatric brain tumor researchers are united to find a cure. The future of diffuse Pontine glioma research rests on novel treatment approaches, the gift of tumor tissue, and on cutting edge scientific approaches
Dr. Alison Bertuch
Texas Childrens Hospital