CHICAGO ( TheStreet) -- In 2009, the U.S. Food and Drug Administration granted accelerated approval to Genentech's drug Avastin to treat patients with advanced brain cancer that was no longer responding to prior therapy. Four years later, the benefit of Avastin as a brain cancer therapy is being called into question because the drug is not helping patients live longer. Avastin when combined with chemotherapy and radiation failed to prolong survival in patients with newly diagnosed brain cancer, also known as glioblastoma, according to findings from two large clinical trials presented at the American Society of Clinical Oncology (ASCO) annual meeting. Oncologists who treat brain cancer patients aren't likely to give up on Avastin altogether because so few drugs are effective against this type of cancer. For patients with advanced disease that is no longer responding to chemotherapy or radiation, Avastin can still delay the growth of new tumors. But Avastin's inability to demonstrate a survival benefit means the drug isn't likely to be used in newly diagnosed brain cancer patients. "Unless we can identify a group of patients that clearly benefits from early use of bevacizumab, it appears that it should not be used in the first-line setting," said Dr. Mark Gilbert of the M.D. Anderson Cancer Center, referring to Avastin's scientific name. In 2011, the FDA revoked the accelerated approval of Avastin for metastatic breast cancer because confirmatory studies showed patients were not living longer but were suffering from additional side effects tied to the drug. Avastin was discovered and developed by Genentech, which was subsequently acquired by Roche. Roche reported Avastin sales of $6.3 billion in 2012. Genentech must submit data to FDA confirming the efficacy of Avastin in brain cancer to support the drug's accelerated approval in 2009. The clinical trial designed by the company to do that -- dubbed "AVAglio" and presented at ASCO on Saturday -- showed Avastin, when added to chemotherapy and radiation, reduced the risk of cancer worsening (tumor re-growth) by 36 percent compared to chemotherapy and radiation alone.