New Details on Suspension of MS Drug Tysabri
3 Patients in Clinical Trials Developed Rare Disease; 2 Died
Doctors' Advice for Patients
Tysabri is given by injection every four weeks. That would mean that
patients who took the drug only while it was on the market got a maximum of one
to three doses, Koralnik tells WebMD.
"We would think they are not at any risk of developing PML now if they
haven't manifested any overt neurological disease different from their
baseline," he says.
Patients should talk to the doctors and have their blood screened, says
Annette Langer-Gould, MD, of Stanford University medical school's neurology
department. Langer-Gould, who also serves in Stanford's department of health
research and policy, contributed to a journal report on one of the confirmed
'Very Rare' Disease
PML is "very rare," even in people with weakened immune systems,
People with MS are not believed to be at higher risk for PML, and the
disease is not thought to be contagious, says the FDA's web site.
The patient who survived the confirmed case of PML temporarily had a
worsening of his symptoms about three months after stopping Tysabri. What may
have happened, says Koralnik, is that the patient's white blood cells were able
to get back into the brain at that point to fight the virus.
"It's clear that Tysabri and other medications of this class are
extremely promising to treat a variety of crippling conditions for which there
is no cure," says Koralnik. "But we have to learn, move forward, and
understand better ... the exact mechanisms to the reactivation of this virus, how
to prevent it in the future, and how to monitor for such reactivation."