Biotech Values

[jbog]

FOLLOW-UP OF TYSABRI PATIENTS WITH PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY

Status update on the two patients who most recently developed PML after receiving Tysabri, marketed by Biogen Idec (BIIB, Market Perform): One, a German patient, is close to a coma and being fed through tubes, though he is breathing on his own. The other patient, a 37-year-old Swede, is in a rehabilitation center near Stockholm and suffering only from mild weakness on one side of his body.

The presenting physician, Dr. Ralf Gold, said the 52-year-old German patient continued to receive Tysabri two months after the presence of the JC virus, which causes PML, was detected in his system. He was diagnosed later than the Swedish patient and thus had a higher level of virus in his brain.

Both patients were subjected to plasmapheresis. Initially, the German patient responded well and showed significantly improved cognitive parameters within a week; however, he subsequently developed a condition known as immune reconstitution inflammatory syndrome, or IRIS. This occurs when the immune system, in eliminating an infection, produces an excessive inflammatory response that can worsen symptoms.

It is now most likely the patient will be permanently brain damaged, according to Dr. Gold. The only question is by how much. He was started on a course of corticosteroids on Friday, the standard treatment for IRIS.

In our view, the appearance of IRIS is likely to renew a certain level of caution. Furthermore, there may be some negative fallout if the German patient dies. Previously, it was stated that PML could be treated if caught early and that plasmapharesis could potentially represent a solution; the fates of these PML patients will be watched carefully to see whether plasmapharesis might, instead, exacerbate the problem under certain conditions.