Multiple Sclerosis Drug May Be Linked to Melanoma

Doctors report 2 cases of the deadly skin cancer developing in patients
taking Tysabri
By Amanda Gardner
Posted 2/6/08

WEDNESDAY, Feb. 6 (HealthDay News) -- 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."

Tysabri (natalizumab), a monoclonal antibody that helps treat autoimmune
disorders such as MS and Crohn's disease, has had a clouded history. It
first received U.S. Food and Drug Administration approval in November
2004, only to be pulled from the market three months later after several
patients in clinical trials developed a rare but deadly viral infection of
the brain called progressive multifocal leukoencephalopathy.

In June 2006, the FDA allowed the drug back on the market but with strict
conditions governing its use.

Just last month, the FDA approved Tysabri to treat people with a moderate
to severe form of Crohn's disease.

But there is basic science to support Mullen's observations.

One of the participants in an earlier study of Tysabri had developed (and
subsequently died of) a metastatic melanoma that appeared as soon as he
got his first dose of the drug, Mullen said.

And in a study done before Tysabri received FDA approval, melanomas in
mice that were given the drug had an increased tendency to detach from the
primary tumor and spread.

Tysabari may have a dampening effect on the immune system that encourages
the formation of the potentially deadly skin cancer, the letter stated.

And now that Tysabri has been approved for people with Crohn's disease,
more people may be at risk, although those with no family history of
melanoma and no moles probably don't need to worry, Mullen said.

"Doctors should ask for a family history of melanoma and do a quick skin
check," he said. "Tysabri isn't the only drug in our arsenal. You could
give the patient something else if you were concerned about that."

More information

The National Multiple Sclerosis Society has more on treatments for MS.

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