The multiple sclerosis treatment Tysabri is finding a welcome market among patients afflicted with the illness, despite the medicine’s risks.
“This has been a learning experience for a lot of Wall Street folks, myself included,” said Mark Schoenebaum, a Bear Stearns biotech analyst, in a recent video interview courtesy of The Healthcare Channel. The lesson, he said, is that MS patients “are willing to accept measured safety risk in order to achieve high levels of efficacy.” Tysabri is about twice as effective as other available drugs, he said.
Tysabri, from Biogen Idec and Elan, was pulled from the market in 2005 after three patients in clinical trials contracted progressive multifocal leukoencephalopathy, a life-threatening brain infection. Two patients died. Two patients were also taking another Biogen drug for MS, Avonex. However, the FDA allowed Tysabri back on the market in 2006 under a program to manage its risks.
Schoenebaum said there are about 20,000 to 25,000 patients on Tysabri, despite the PML experience. He called the relaunch “solid.” But he said Biogen’s guidance on peak use of the drug at 100,000 patients by the end of 2010 might be “a little bit aggressive.”
As for a recent letter sent by the companies to doctors about Tysabri’s risk for liver toxicity, Schoenebaum told the Health Blog in an email that it would have “no effect” on the uptake of Tysabr