Dr. Sarah Injac
Emerging Research Grant
Baylor College of Medicine
Dr. Sarah Injac’s Research
Dr. Sarah Injac, is a welcome addition to the Emerging Research Grant recipients. Her work at Baylor College of Medicine offers hope to children with Medulloblastoma, the most common malignant brain tumor of childhood with approximately 500 cases diagnosed in the United States each year. Overall it accounts for approximately 20% of all pediatric brain tumors. While it is most often diagnosed as an isolated mass, medulloblastoma is an aggressive tumor, and a substantial minority patients have disease that has already spread at diagnosis. The current standard therapy for medulloblastoma consists of a combination of surgery, radiation and chemotherapy. This combined approach results in cure rates of approximately 75%. For patients who fail to respond to initial therapy or have disease that recurs following treatment, however, the outcomes remain dismal. There are currently no effective second line therapies for relapsed or refractory disease. In addition, many long-term survivors of childhood medulloblastoma face significant treatment-related side effects. Long studies of these patients have shown high rates of learning issues with associated academic failure and unemployment, as well as hormonal problems, and an increased risk for secondary cancers. New therapies, therefore, remain urgently needed.
Despite major advances in recent years in our understanding of the biology of medulloblastoma, we have yet to significantly change our approach to treating these devastating tumors. This is in part because new drugs require extensive testing to determine dosing and side effects and still frequently fail to show significant benefit when used in patients. With this in mind, we developed an approach in which we use available molecular information to identify drugs already in clinical use that have the potential to be repurposed for the treatment of medulloblastoma. Because these medications are already in use, they have the potential to be rapidly translated into clinical use.
As we recently reported, using this approach we were able to identify a family of heart medications with a long history of clinical use, the cardiac glycosides, from among over 1,300 candidate drugs as potential treatments for medulloblastoma. We were then able to show that one of these medications, digoxin, significantly prolonged survival in mouse models of high risk medulloblastoma. One limitation of drug testing in mouse models, however, is that mice and humans process drugs at different rates which can complicate translation to patients. In our current study, due to the generous support of the Pediatric Cancer Research Foundation, we will use a continuous infusion of digoxin to mirror as closely as possible the way digoxin is dosed in human heart patients. If we are able to show an improvement in survival under these conditions, it will serve as the final step to developing a clinical trial of digoxin in the treatment of medulloblastoma.