Threshold Pharmaceuticals Inc., of Redwood City, Calif., initiated a clinical trial of TH-302 in combination with bevacizumab (Avastin, Roche AG) in patients with recurrent high-grade astrocytoma including glioblastoma. TH-302 is a novel small-molecule hypoxia-targeted prodrug that is selectively activated by the low oxygen conditions believed to be induced in tumors by antiangiogenic therapies such as bevacizumab.