Hello DPL2014,

To answer your two questions…

1. No, the PML risk is not higher on dose extension. PML risk is reduced by 88% on dose extension according to Barts (renowned London School of Medicine) MS Blog. Please click the link http://multiple-sclerosis-research.blogspot.com/ and click the ClinicSpeak PML Risk Guide to expand it to full screen.

The second yellow line from the top is where we want to focus. For those who have a JCV titer over 1.5 the PML risk is 1 in 5,000 during months 1-12. The PML risk is 1 in 1,111 during months 12-24. The risk is 1 in 333 during months 25-36. The risk is 1-100 when the JCV titer is over 1.5 and Tysabri is taken more than 60 months on standard 4-week dosing. You will notice the progression in risk taking Tysabri every 4 weeks.

The PML risk is not 1/1,111 AFTER two years of JCV+ over 1.5 on 4-week dosing. It is 1/1,111 BEFORE two years.

So, what is the actual risk for those on dose extension? To me (please note this is only me expressing an unqualified opinion based on my review and I most certainly can be wrong!), it appears the PML risk is about 1 in 400 for those who are JCV+ and on extended dosing beyond 4 weeks as a group. Right now, a stratified more specific breakdown is not available. However, that data is being compiled and when it is presented we will know what the PML risk is stratified according to JCV titers and length of treatment.

Possibly, based on the PML risk demonstrated in the 4-week chart available at Barts website, PML risk will be lower at lower titers. However, that is only speculation w/o the facts! We really have to wait and see. Interesting also, will be the PML risk for 3, 4, 5, 6, 7+ years at various titer levels. It takes time to gather statistically meaningful data. We have no choice but to be patient.

What we have learned so far is that overall, for the whole group on extended dosing, extending time between doses reduces PML risk by a whopping 88%. Plus, I would think anyone would be healthier on dose extension because less immune suppression would mean your immune system is better able to function more normally. The trick with Tysabri is take only what you need to keep MS in check. Obviously, that varies with each individual. My guess is that many neuros will settle on 6-week dosing AFTER the first year or two of Tysabri IF the person is doing well. JMHO. But the optimum time between doses is bound to vary between PwMS.


2. You asked if PML risk decreases the longer you go between doses. That data is still being complied. JMHO, I cannot see how lengthening time between doses would not decrease PML risk. But it will be interesting to see the differences in PML risk between 5, 6, 7, or 8 weeks when the data is available. My best thoughts to you!

Hello Linda, thank you for your kind thoughts. Switching from Tysabri to Ocrevus took a lot of life away from my spouse. But switching to any other DMT would have been far worse, IMO. JMHO. If nothing else I hope those who are JCV+ and healthy on Tysabri consider long and hard before going off it. MS really sucks... its too easy to forget that on Tysabri… until you are off it.