FDA rejects Biogen's subcutaneous Tysabri in multiple sclerosis

Biogen CEO Michel Vounatsos
Biogen CEO Michel Vounatsos (Biogen)

The FDA has rejected Biogen’s request for approval of a subcutaneous formulation of Tysabri. Biogen suffered the setback shortly after receiving approval for the multiple sclerosis drug in the EU.

Intravenous Tysabri racked up another year of blockbuster sales in 2020. As Tysabri emerged from its early safety problems to become a big seller, Biogen ran clinical trials of a subcutaneous formulation of the drug designed to be more convenient for patients. Biogen completed the second of the two studies in 2014 but only filed for FDA approval of the formulation last year.

Now, the FDA has extended the wait for a subcutaneous version of Tysabri. The agency hit Biogen with a complete response letter that states it is unable to approve the formulation on the strength of the application submitted in June.

Biogen is yet to share details of why the FDA rejected the drug or what it will take to get the dossier ready for resubmission, saying only that it is evaluating the letter and will determine the next steps in the U.S. in the future. The European Commission approved the subcutaneous formulation last month, and Biogen still plans to seek authorization in other countries. 

The U.S. is a critical market for Tysabri, though. Last year, Biogen recorded more sales of intravenous Tysabri in the U.S.—$1.1 billion—than in the rest of the world combined. Biogen has continued to bring in blockbuster sales as competition for the market has intensified but could face the additional challenge of off-patent rivals in the years to come.

Tysabri is protected by U.S. methods of treatment patents that are due to expire in 2023 and 2027. Sandoz is among the companies to express an interest in developing a biosimilar copy of the multiple sclerosis drug, picking up the rights to commercialize Polpharma Biologics’ version in 2019. Biogen CEO Michel Vounatsos set out the need for a subcutaneous version days before the FDA rejection.

“When we look at the prescriber’s landscape for Tysabri, which is a tremendous success, it's extremely limited. And is it because of the infusion centers? Is it because of the risk of PML? Probably both. Here we are combining the opportunity of accessing high efficacy with the subcutaneous dosing. So, we should be in a position to enlarge the use and the targeting for Tysabri,” Vounatsos said on a first-quarter results conference call with investors.