Update on Risk of PML Infection Associated with Tysabri Presented at CMSC 2024

Promising results from the Tysabri Outread: Unified Commitment to Health (TOUCH) Prescribing Program were reported at the 2024 Annual Meeting of the Consortium of Multiple Sclerosis Centers (CMSC). Researchers found that, although cases of progressive multifocal leukoencephalopathy (PML) associated with Tysabri (natalizumab; Biogen, Cambridge, MA) increased in the United States from 2009 to 2015, the incidence of PML cases remained stable from 2016 to 2023. These results match those found in other studies analyzing PML rates in other countries and suggest that updated PML risk stratification efforts initiated in 2016 are being effectively incorporated into treatment decisions by US clinicians.

Researchers analyzed US PML incidence rate data from the TOUCH Prescribing Program from 2009 through August 1, 2023. The analysis revealed that the number of people in the US treated with Tysabri (defined as receiving ≥1 dose within that calendar year) increased from 37,284 to 116,752 individuals from 2009 to 2023.

• From 2009 to 2015, cumulative PML incidence per 1000 people increased from .268 (95% CI, .129 to .493) to 2.248 (95% CI, 1.933 to 2.600).
• From 2016 to 2023, the rates remained stable (2.212 [95% CI, 1.912 to 2.546] to 2.107 [95% CI, 1.852 to 2.387])
• There has been a total of 246 confirmed cases of PML reported in people taking Tysabri, as of 2023.

Tysabri is approved as a monotherapy for relapsing forms of multiple sclerosis (MS) in adults, including clinically isolated syndrome (CIS), relapsing-remitting MS (RRMS), and secondary progressive MS (SPMS). The medication’s label contains a Boxed Warning for PML.

The authors of this study are affiliated with Biogen and Cytel, a statistical software development company.