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.

2 thoughts on “Clinical outcomes of natalizumab-associated progressive multifocal leukoencephalopathy”

  1. "At the time of analysis, 25 patients (71%) had survived." What was the time frame for that percent? I know that there are several progressive multifocal leukoencephalopathy treatments but that percentage seems incredibly high. I read a study published in the Journal of NeuroVirology about: "Treatment of non-AIDS progressive multifocalleukoencephalopathy with cytosine arabinoside" and their results suggests a 36% survival rate after 1 year, which they even state to be higher then expected compared to previous studies showing only 10% survival rate after a 1 year period.Here's the study:

  2. Re: "Clinical outcomes"The following is the latest figures from Biogen-Idec:As of 1st February 2012: 44 patients have died (21%. Most of the deaths have occurred within approximately 2-3 months after PML diagnosis. The median time to death was 2.1 months (range, 0.2 to 15.2 months) for 37 deaths as of December 1, 2011.163 patients are alive (79%). It is too early to draw conclusions about the outcomes of patients who develop PML while on natalizumab treatment. The median duration of follow-up in survivors was 12.2 months (0.8 – 41.3 months) for 152 survivors as of December 1, 2011.Source: Biogen Idec Data on file.

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