The purpose of this study is to evaluate the safety and effectiveness of an investigational drug called RO4929097 at different dose levels, when added to the standard treatment for newly diagnosed glioma in patients who will be having surgery. This standard treatment consists of radiotherapy combined with temozolomide, a drug used to treat gliomas. Radiotherapy and temozolomide are the current standard treatment for these brain cancers.

RO4929097 works by inhibiting a protein called gamma-secretase. Gamma-secretase is involved in the growth of cancer cells, particularly cancer stem cells. Cancer stem cells are more resistant to radiotherapy and temozolomide than regular cancer cells. Researchers hope that RO4929097 will improve the effectiveness of these treatments by acting on cancer stem cells.

Samples of each patient's tumor will be obtained during surgery to analyze drug levels of RO4929097, to determine the effects of RO4929097 on the tumor, and to assess molecular characteristics.