There are now 145 confirmed PML cases as of July 5, 2011. Please note there has now been over 165,000 years of exposure to Natalizumab. Therefore the number of PML cases has to be seen in the context of the number of MS’ers receiving the drug.
The following graph provides the risk by treatment period.
*Yousry TA, et al. N Engl J Med. 2006;354:924-933. This is the observed rate of PML in clinical trials in MS’ers who received a mean of 17.9 monthly doses of natalizumab.
The post-marketing PML rate is calculated as the number of PML cases since reintroduction in patients that have had at least 1 dose of natalizumab.
Incidence estimates by treatment period are calculated based on natalizumab exposure through June 30, 2011 and 145 confirmed PML cases as of July 5, 2011.
The incidence for each period is calculated as the number of PML cases divided by the number of patients exposed to natalizumab. For example for 25 to 36 infusions all PML cases diagnosed during this period is divided by the total number of MS’ers ever exposed to at least 25 infusions and therefore having risk of developing PML during this time.
Source: Biogen Idec, data on file.
Other posts on this blog concerning Natalizumab:
24 Jul 2011
“The expectation of Natalizumab therapy is to prevent future attacks; it does little to repair previous damage. In MS’ers with early disease suppressing on-going disease activity allows endogenous repair to occur; …
23 Jul 2011
Background: Natalizumab is a biological therapy; that is it is a protein and therefore you immune system can reject it as being foreign and make antibodies against the drug. This is what we aim to achieve with vaccines. …
21 Jul 2011
“This video blog is response to a query from one of the readers for more information on this topic and in response to an audit we performed on this subject among the MS’ers on Natalizumab at the Royal London Hospital.” …
17 Jun 2011
The observed clinical trial rate was in PwMS who had received a mean of 17.9 monthly doses of natalizumab. In comparison, the post-marketing rate is calculated as the number of PML cases since reintroduction in PwMS who …
Etc. search term “natalizumab”