Physicians in Boston have reported two cases of melanoma (skin cancer) that
developed in women who were administered Tysabri® (natalizumab) to treat their
MS. John T. Mullen, MD, and two colleagues at Beth Israel Deaconess Hospital,
Boston reported the cases in the New England Journal of Medicine.

The melanomas developed early in the course of treatment, but it cannot be
confirmed from these 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,
which is a spot on the eye that can develop into melanoma.

Tysabri is a laboratory-produced monoclonal antibody that is approved for
individuals with relapsing forms of MS to delay the accumulation of physical
disability and reduce the frequency of clinical exacerbations. It is designed to
impede movement of potentially damaging immune cells from the bloodstream,
across the "blood-brain barrier" into the brain and spinal cord.

Dr. Mullen's team reports that a 46-year-old woman developed a melanoma shortly
after receiving her first dose of Tysabri. In a 45-year-old woman with a family
history of melanoma, an ocular nevus developed into a melanoma after several
doses. A case of melanoma also appeared in the AFFIRM study (which involved 942
individuals with relapsing MS, who received either Tysabri or placebo by IV
infusion every four weeks for more than two years) in a patient with a history
of malignant melanoma.

From these reports, a causal link between Tysabri and the occurrence of melanoma
cannot be determined. However, given these events, the authors recommend that
Tysabri not be administered to people with a history or family history of
melanoma.
"Neurologists who have patients who report a family history of melanoma or have
unusual 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 report and a
surgical oncologist at Beth Israel. The report also stated that Tysabri may have
a dampening effect on the immune system that encourages the formation of the
potentially deadly skin cancer.

"This new report warrants another dose of cautious observation for Tysabri,"
adds MSF Medical Advisor Ben Thrower, M.D. "Potential Tysabri patients should be
screened for any history of melanoma, as mentioned. One could argue that any
prior abnormal tissue growth may make Tysabri use riskier for that patient. The
thought is that maybe Tysabri interferes with tumor cell surveillance and one
would have to question whether this applies to all cancer types. In our
practice, Tysabri is only considered in patients with active MS, who have failed
both interferon and glatiramer acetate This new report indicates that Tysabri is
probably not ready for consideration as a first-line option for RRMS."




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