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Questions and Answers on Tysabri
(natalizumab)
Regarding Lifting of the Clinical Hold
1) Why is FDA lifting the clinical hold?
We received detailed information on the extensive re-examination
that Biogen and Elan undertook on all patients who had received
natalizumab in clinical studies under an IND. No additional cases of
PML were identified. The better understanding of the actual
occurrence of PML in these patients permitted better estimation of
the potential risk of PML occurring in the future. In addition,
Biogen has proposed a resumption of natalizumab administration under
an IND study with very specific plans for close monitoring of
patients.
2) Will Tysabri be available to all patients?
Biogen has proposed to FDA only to resume administration of
natalizumab to patients who had previously been receiving the drug
within an IND study at the time of the suspension of use in February
2005. Those patients would need to discuss with their Study
physician the potential risks and potential benefits of resuming
treatment with natalizumab, and will be able to make a decision
after that discussion. Biogen has not proposed to administer the
drug to anyone who had not previously been receiving it under an IND
study. Biogen has submitted an application to FDA to resume
marketing the drug for more widespread use. That application has a
due date for a decision by FDA in late March 2006.
3) What happens to the other holds on similar products and what
is our process for lifting these holds?
The lifting of the clinical hold on natalizumab may lead to requests
from other product sponsors to begin or resume clinical studies for
molecules that act in a similar manner. FDA will consider each of
those proposals as they are received. An important aspect to
consider is whether the potential risk of a specific product is
reasonable in the setting of a specific disease, type of patient,
and other currently available therapies for that type of patient.
4) Is there still a significant safety concern with the product,
and if so, why did we lift this hold?
FDA remains very concerned about the potential for PML associated
with natalizumab use. However, the currently available information
are not adequate to clearly define the level of risk or the exact
circumstances when this risk occurs. Furthermore, the existing
efficacy data with natalizumab indicate this is a very effective
product and multiple sclerosis is a devastating neurologic disease.
Therefore, if a study is done in a manner that provides as much
safety monitoring as feasible, it is reasonable to resume studying
this product under IND to obtain more safety-related information
that may permit us to begin to better understand how large or small
the true risks associated with natalizumab are.
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Date created: February 15, 2006 |
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