This Thursday a government panel ruled that Avastin is too risky in case of breast cancer treatment. The Food and Drug Administration commission usually follow the decisions of the advisory panel and most likely FDA will delay the approval of the drug.

The term for FDA to rule over Avastin was set to February the 23, 2008, but the panel’s decision might change that. Avastin is the most significant drug of Genentech Inc. which shares have dropped 8.4 percent this Wednesday.

If the FDA will delay Avastin’s approval for breast cancer, Genentech’s shares will stay flat for at least next year, analysts say. Avastin is already approved for colorectal and non-small cell lung cancers. The drug is based on the technology that stops blood supply to the tumors preventing them to grow.

The company is expecting Avastin to become one of the world’s most selling drugs. The panel’s decision was somehow unexpected due to also the reason of the rejection. Avastin was considered not beneficial in treatment of breast cancer because only slows the progress of the disease without extending patients lives.

This argument appears awkward and unexpected, because the drug was approved to treat other similar illnesses without providing an increase in survival.