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Here's the problem with Tysabri, IMHO.

The reason it was yanked is because PML symptoms are so similar to MS symptoms that it is impossible without an MRI, lumbar puncture, or brain biopsy to determine if the patient is just experiencing an MS exacerbation or is experiencing PML symptoms.

To make matters more complicated, the normal thing a neuro would do if he saw a MS patient with worsening symptoms would be to put them on a course of IV solumedrol (steroids) and if the cause of the worsening symptoms was PML, then that would make the PML become even more aggressive. (and since 80 percent of people harbor the JC virus which causes PML, it does not good to try to avoid people with the JC virus when administering Tysabri.)

Tysabri was shown to reduce exacerbations by 67 percent versus 33 percent for the other treatments, but the EDSS (disability scores)of Tysabri versus a placebo were no better than those patients treated with an interferon versus a placebo (about a 12 percent reduction). Most neuros will tell you lesion load has no impact on disability.

I can see Tysabri coming back as a Crohns or RA treatment sooner than as an MS treatment. And if it comes back as an MS treatment with a warning about immunosuppressants (i.e. steroids), I think there will be problems getting it accepted widely by the MS community.

Another issue with Tysabri is the cost, it is by far the most expensive of the present treatments because it has to include the cost of the infusion, when the other treatments are self injected.

There will be a market for Tysabri. Those who have side effects from the interferons, or have developed antibodies to them so that they are useless, or perhaps those with liver problems from the interferons. There are plenty of people who refuse to take a CRAB (copaxone, rebif, avonex or betaseron), but not all those people don't take them because the other treatments have failed. They just don't want to take that strong a medication, or use alternative therapies like LDN. Those that have refused to be on a CRAB for that reason, will also probably refuse Tysabri.

I do hope Tysabri comes back to the market, I just don't think it will have as wide a market appeal as there was before the PML was discovered.

Thank you very much for this informative explanation.

I see so many people getting caught in emotional half-arguments. I know investors are at a huge loss for now, are filled with hyperbole and are indiscriminately blaming all persons and organizations for their loss. MS patients and relatives of MS sufferers are also easily drawn to the side that views the cancellation of Tysabri as unnecessary.

I hope the companies involved in Tysabri are fortified enough to continue research and will find ways to manage problems with the JC virus.

Please post again if you have any insight into possible remedies for research. Thanks again.

Yes, PML signs are similar to those of MS, but no Lumbar punctures have been done in the detailed followup testing of the patients who have taken Tysabri. In fact, probably more is now being learned about PML and its differences from MS than ever.

Tysabri on monotherapy has a sterling record. The problem is quite evidently immunosuppressant synergies, which the label already warns against.

As this article brings out, the safety profile of other drugs in accepted use is far worse than anything associated with Tysabri. I believe the drug comes back with a warning label and becomes the standard of monotherapy in a short time. Neuros will undoubtedly demand waivers from patients, but patients will want the drug. From what I've read, the EDSS scores are not a particularly great way to guage actual quality of life.