The FDA grants fast track status to drug candidates that are designed to treat serious diseases, and which may be superior to current therapies. Fast track status includes additional collaboration between Genzyme and the FDA, and will allow Genzyme to submit portions of its application for the drug alemtuzumab as they are completed, rather than when all clinical testing is complete.

It also means alemtuzumab could get approved more quickly. Drugs that receive fast track status are more likely to get a priority review, which is complete in six months instead of the usual 10 months.