Exploratory Study of XL765 or XL147 in Subjects With Recurrent Glioblastoma Who Are Candidates for Surgical Resection

The purpose of this study is to measure what effect the study drug XL765 or the study drug
XL147 has on tumor tissue in subjects with recurrent glioblastoma (GB) who are candidates
for surgical resection. XL765 and XL147, the two investigational agents examined in this
study, are potent inhibitors of PI3 Kinase (PI3K). In preclinical studies, inactivation of
PI3K has been shown to inhibit growth and induce apoptosis (programmed cell death) in tumor
cells.