Cohn & Wolfe has been called in to handle global pre-launch comms for the MS drug, which is currently in phase two.
Genzyme appointed C&W's healthcare team after a three-way pitch, understood to have included Weber Shandwick and Edelman.
The global account team will be drawn from Cohn & Wolfe's New York and London teams. The account will be led by global head of health Mike Kan and co-director of Cohn & Wolfe's New York health practice Lisa Talbot.
'The Alemtuzumab programme is very exciting,' said Kan. 'We have deep experience in MS, which helped us to be selected as Genzyme's comms partner.'
There are currently 100,000 people suffering from MS in the UK. The condition is usually diagnosed between the ages of 20 and 40.
Recent research conducted by the Multiple Sclerosis Society found that Scotland had the highest incidences of MS in the world. It is believed the further people live from the equator, the more likely they are to develop MS.
Symptoms of the condition can vary and include difficulties with balance and dizziness, fatigue, blurred vision and numbness.
Genzyme's products and services are focused on rare inherited disorders, kidney disease, orthopaedics, cancer, transplant and immune disease.