Tysabri Observational Cohort Study - Multiple Sclerosis (MS) Registries

This is an observational cohort study utilising all available data from the Tysabri TOUCH
(TYSABRI Outreach: Unified Commitment to Health) prescribing programme (US) supplemented with
data from European Union (EU) multiple sclerosis (MS) registries to estimate the risk of PML
and other serious opportunistic infections (OIs) among patients on Tysabri who have switched
from newer DMTs (including fingolimod, dimethyl fumarate and teriflunomide) and the
established DMTs (interferon beta and glatiramer acetate).

This study will provide cumulative data from its two components separately: a retrospective
component (data captured prior to 1 January 2016) and a prospective component (data captured,
and patients followed up, from 1 January 2016 through 31 December 2023; total prospective
study duration of 8 years). All patients who switched to Tysabri from another DMT through 31
December 2020 will be included. The study will continue to follow-up patients until 31
December 2023 to allow for a minimal follow-up of 3 years.

Key Inclusion Criteria:

- All TOUCH and available EU MS registry patients who have switched from DMTs (including
fingolimod, dimethyl fumarate, teriflunomide, interferon beta and glatiramer acetate)
and have one or more infusion(s) of Tysabri.

Key Exclusion Criteria:

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply