Elan, a biotechnology company based in Ireland, has closed its Tysabri (natalizumab) collaboration transaction with Biogen Idec, which was originally announced on February 6, 2013.

Elan has received $3.25 billion in cash and will receive double digit tiered royalty payments, on all indications, for the life of the complete Tysabri asset. For the first 12 months, Elan will receive 12% royalties on in-market sales of Tysabri, and thereafter, Elan will receive 18% royalties on in-market sales up to $2 billion and 25% royalties on in-market sales exceeding $2 billion. In 2012, in-market sales of Tysabri were $1.6 billion.

Tysabri is approved in more than 65 countries. In the U.S., Tysabri is approved as a monotherapy for relapsing forms of multiple sclerosis (MS), generally for patients who have had an inadequate response to, or are unable to tolerate, an alternative MS therapy due to the risk of progressive multifocal leukoencephalopathy (PML). Data from the phase III AFFIRM trial, which was published in the New England Journal of Medicine, showed that after two years, Tysabri treatment led to a 68% relative reduction (p<0.001) in the annualized relapse rate when compared with placebo and reduced the relative risk of disability progression by 42%-54% (p<0.001).

As a result of the termination of the collaboration, Tysabri will be marketed and distributed solely by Biogen Idec.