Clinical outcomes of natalizumab-associated progressive multifocal leukoencephalopathy

Vermersch P, et al. Neurology. 2011 May 17;76(20):1697-704.

An assessment of the clinical outcomes and survival in 35 patients with natalizumab-associated PML.
At the time of analysis, 25 patients (71%) had survived. Survivors were younger and had lower pre-PML disability scores and a shorter time from symptom onset to diagnosis (mean 44 vs 63 days) compared to fatal cases. In the non-fatal cases, 86% had unilobar or multilobar disease on brain MRI at diagnosis, whereas 70% of those with fatal cases had widespread disease. Among survivors with at least 6 months follow-up, disability levels were evenly distributed among mild, moderate, and severe, based on clinician-reported scores. 

"In summary, it is bad news if you develop PML on Natalizumab. If you are on Natalizumab please urge your neurologist to discuss the risk with you and to send your bloods off to see if you have previously been exposed to the virus. This information will allow you to better define your risk of developing this complication."

COI: I was the Chief Investigator on the Affirm trial in the UK and have received payments as a consultant from Biogen-Idec in relation to Natalizumab and PML.