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Jul 02, 2008
Previous Report of Two Cases of Melanoma
(Skin Cancer) Reported in People Taking Tysabri for MS Updated with Company
Rebuttal
Originally Reported on February 7, 2008 - See Update Below, July 2,
2008
Physicians in Boston have reported two
cases of melanoma (skin cancer) that developed in women in their practice
who were administered TysabriŽ (natalizumab, Biogen Idec and Elan Pharmaceuticals)
to treat their multiple sclerosis. John T. Mullen, MD, and two colleagues
(Beth Israel Deaconess Hospital, Boston) reported the cases in the New
England Journal of Medicine (2008;358[6]:647-8). The melanomas developed
early in the course of treatment, but it cannot be confirmed from these
case reports that Tysabri caused them. However, the authors advise against
treating individuals with Tysabri when there is a personal or family
history of melanoma or in patients with atypical moles or ocular nevus
(spot at the back of the eye).
Background: Tysabri is a
laboratory-produced monoclonal antibody that is approved for patients with
relapsing forms of MS to delay the accumulation of physical disability and
reduce the frequency of clinical exacerbations. It is designed to hamper
movement of potentially damaging immune cells from the bloodstream, across
the "blood-brain barrier" into the brain and spinal cord.
Details: Dr. Mullen's team
reports that a 46-year-old woman developed a melanoma shortly after
receiving her first dose of Tysabri, and an ocular nevus developed into a
melanoma after several doses in a 45-year-old woman with a family history
of melanoma . A case of melanoma also appeared in the AFFIRM study - which
involved 942 individuals with relapsing MS, who received either Tysabri or
inactive placebo by intravenous infusions every four weeks for more than
two years - in a patient with a history of malignant melanoma.
It cannot be confirmed from these reports
that there is a causal link between Tysabri administration and the
occurrence of melanoma. However, given these occurrences, the authors
recommend that Tysabri not be administered to people with a history or
family history of melanoma.
"These reports raise concern and they underscore the importance of
carefully tracking patients on powerful medications like Tysabri,"
said Dr. John R. Richert, executive vice president of research and clinical
programs at the National MS Society. "This drug is relatively new to
the market, and as experience grows we are bound to learn more about its
benefits as well as possible adverse events," Dr. Richert added.
JULY 2, 2008 UPDATE:
In a letter to the editor published in the July 3, 2008 issue of the
New England Journal of Medicine (2008; 359[1]:99-100), Dr. Michael A.
Panzara and other representatives of Biogen Idec, Inc., pointed out that
individual case reports, such as were reported by Dr. Mullen and
colleagues, do not provide an adequate basis for proving cause and effect.
The authors reviewed safety data from several clinical trials of Tysabri
involving thousands of people and found that the incidence of melanoma was
similar in those who received Tysabri (0.07%) compared to those who
received inactive placebo (0.10%). In addition, a review by the authors of
the company's post-marketing safety surveillance data did not indicate in
increased risk of melanoma in over 21,000 treated patients (as of December
2007).
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