A drug currently used to treat colon cancer in people successfully treated a type of brain tumor, called a glioma, in a dog named "Petey". After removing the tumor, Dr. Simon Platt administered the drug to the brain where it prevented the tumor from returning. The next step is to conduct a larger study that includes more dogs. If successful, the drug may be used in clinical studies of humans to treat glioblastomas, a similar form of brain cancer that affects roughly 13,000 people annually and for which there is currently no cure.