Roche’s best-selling cancer drug, Avastin, is currently the subject of an unprecedented hearing set to take place this week. Federal regulators have scrutinized the once-promising drug after it proved to carry more risks than benefits in patients taking the medication as a treatment for breast cancer. In fact, the U.S. Food and Drug Administration granted provisional approval to Avastin for breast cancer in 2008 but have since revoked that decision. This week’s hearing marks Roche’s last-ditch efforts to appeal the FDA’s rejection its blockbuster breast cancer drug.

The decision rendered by the FDA’s appeals panel and the agency’s Commissioner, Margaret Hamburg, will undoubtedly affect the process for future conditional approval of various life-saving cancer drugs. Moreover, Roche Genentech’s opposition of the FDA’s withdrawal decision is unique in that the company is now the first to formally appeal such a decision.

A panel of independent experts selected by the FDA will vote on the issues, following the trial-like hearing in which both FDA scientists will argue their case and representatives from Roche will defend their position. Regardless of the outcome, Avastin will still remain on the market due to its previous approval for the treatment of various other cancers. It can also still be prescribed by doctors for “off-label” breast cancer treatment, even if the drug’s label is changed to indicate the loss of such an indication.

The actions associated with this week’s hearing are being closely monitored by the pharmaceutical industry, as its outcome will certainly set a precedent of policy for the approval of cancer drugs, as well as the efficacy of Roche’s aggressive lobbying efforts on Capitol Hill.