Perrigo Company plc / Elan Corporation plc

Multiple Sclerosis (Tysabri royalty exposure)

Disease Overview

Multiple sclerosis is an autoimmune CNS demyelinating disease. Tysabri (natalizumab, an anti-VLA-4 monoclonal antibody co-developed by Biogen and Elan) is a high-efficacy disease-modifying therapy used after JCV stratification, given the PML risk that triggered its 2005 withdrawal and 2006 re-launch under TOUCH REMS.

Competitive Landscape

Perrigo's interest in Elan was not therapeutic — it was tax structural plus a single financial asset: the Tysabri royalty stream Elan had retained when it sold its 50% Tysabri stake to Biogen in early 2013 for $3.25B + escalating royalties. At deal time (July 2013), Tysabri was a ~$1.5B/year MS franchise inside a relapsing-remitting MS market increasingly disrupted by oral DMTs (Gilenya/Novartis 2010, Aubagio/Sanofi 2012, Tecfidera/Biogen Mar 2013). The deal's primary value driver was Perrigo's tax inversion to Ireland — which Wells Fargo's David Maris and RBC's Randall Stanicky later flagged would generate a $1.9B Irish Revenue tax claim plus an $873M IRS claim (~$3B combined) over the Tysabri IP transfer. Perrigo ultimately divested the royalty in 2017 to Royalty Pharma for up to $2.85B, validating that the Tysabri stream — not Elan's neuro pipeline — was the only durable Elan asset Perrigo needed.