"Almost immediately after a 46-year-old woman with multiple sclerosis received her first dose of the drug Tysabri, a mole that had been on her shoulder for years suddenly took on a dangerous new character.

It turned out to be a melanoma that spread like wildfire. The woman now has just a few months to live.

At almost the same time, a 45-year-old woman who also has multiple sclerosis developed melanoma in her retina after receiving several doses of Tysabri. She had a family history of melanoma and also had atypical moles on her body; the mole on her retina went back at least nine years.

Although these are just two -- albeit dramatic -- examples, the authors of a letter in the Feb. 7 issue of the New England Journal of Medicine are cautioning doctors who care for MS patients to keep this potential risk in mind.

"Neurologists who have patients who report a family history of melanoma or have funny moles should send them to a dermatologist first. Don't just start them on drugs [Tysabri]," said Dr. John Thomas Mullen, co-author of the letter and a surgical oncologist with Beth Israel Deaconess Medical Center, in Boston.

"I can't say it's cause-and-effect definitively because it's just an observation, but the first patient had had that mole forever. She took the drug and almost instantaneously the lesion changed," added Mullen, who saw both patients.

"We don't know if the two are related right now," said Patricia O'Looney, vice president of biomedical research at the National Multiple Sclerosis Society. "There are so many people taking Tysabri, we should go forward with caution... One should always consult with their doctor and go over their personal family history and decide what is best."

http://www.msrc.co.uk/index.cfm?fuse...ow&pageid=1905

http://content.nejm.org/cgi/content/extract/358/6/647-a

Cherie