Yesterday 12 members of the agency's Gastrointestinal Drugs Advisory Committee and the Drug Safety and Risk Management Advisory Committee voted in favour of recommending the treatment for moderate-to-severe Crohn's disease in patients who have failed or cannot tolerate available therapies. Three members were opposed to the decision while two abstained from voting. The regulator, however, does not have to follow its advisor's recommendations. It is unclear whether it will do so or not - an internal report issued by the FDA prior to yesterday's advisory meeting raised concerns over the use of Tysabri for this chronic disease. The report said that the efficacy of the drug wasn't "clearly distinguished" from current therapies in clinical trials. Two weeks ago the European regulators (EMEA) drew this very conclusion and rejected Tysabri's approval as a treatment for Crohn's disease on the grounds that there was "insufficient evidence" that the benefits outweighed the risks. NICE, the UK government's drug watchdog, had previously recommended against approving it. Massachusetts-based Biogen Idec and Irish company Elan, the firms who are jointly marketing the drug, have indicated they will appeal this decision and will be hoping that the FDA's decision doesn't go the same way. The two firms said they "will continue to work closely with the FDA in the weeks ahead with the goal of making [the treatment] available". Tysabri, a humanised monoclonal antibody (mAb) alpha-4 antagonist is already approved for relapsing forms of multiple sclerosis (MS) in the US and for elapsing-remitting MS in Europe.