The purpose of this study is to compare the safety and efficacy of two doses of AP 12009 and standard chemotherapy in adult patients with recurrent high-grade glioma (anaplastic astrocytoma [AA], WHO grade III; or glioblastoma [GBM], WHO grade IV). AP 12009 is a phosphorothioate antisense oligodeoxynucleotide specific for the mRNA of human transforming growth factor-beta2 (TGF-beta2). The growth factor TGF-beta plays a key role in malignant progression of various tumors by inducing proliferation, invasion, metastasis, angiogenesis and escape from immunosurveillance. It has been shown that in a number of tumor types the degree of TGF-beta production strongly correlates with tumor grade and stage. In patients with high-grade glioma, the TGF-beta2 overexpression is associated with disease stage, clinical prognosis and the immunodeficient state of the patients.