Sandoz launches first biosimilar Tysabri in US

Biogen is facing biosimilar competition to its big-selling multiple sclerosis therapy Tysabri in the US for the first time, as Sandoz enters the market.

The launch of Sandoz's Tyruko biosimilar of Tysabri (natalizumab) comes two years after the product was approved by the FDA, and after Biogen's final patent protection for the product came to an end in the US. Some biosimilars are already on the market in Europe and other markets.

The entry of Tyruko was delayed by the need to develop a blood test for antibodies to the JC virus (JCV), which helps doctors assess the risk of a patient developing progressive multifocal leukoencephalopathy (PML), a rare side effect of natalizumab treatment.

Like Tysabri, Tyruko has to be supplied via a risk evaluation and mitigation strategy (REMS) programme that includes JCV testing. While Biogen has its own test for Tysabri, Sandoz has partnered with Labcorp on an assay that can be used with the biosimilar.

In the first nine months of the year, Biogen recorded worldwide Tysabri sales of almost $1.27 billion, down from $1.3 billion in the same period of 2024, although US sales grew by around $30 million to $720 million.

The launch adds to the pressure on Biogen's MS franchise, already exposed by competition to other products like former $4.4 billion blockbuster Tecfidera (dimethyl fumarate), which made $740 million in the first three quarters of 2025, as well as its older beta interferon products.

Tyruko was developed by Netherlands and Poland-based pharma group Polpharma Biologics, and Sandoz acquired worldwide commercial rights to it in a 2019 deal. Along with the US, it has been launched in 14 European markets.

The product is the "first and only FDA-approved natalizumab biosimilar for the treatment of relapsing forms of multiple sclerosis (MS)," said Sandoz in a statement, and is the first biosimilar of any biologic drug for MS in the US.

It has been approved for all of Tysabri's indications, which also include the treatment of Crohn's disease, a form of inflammatory bowel disease.

"For people living with multiple sclerosis, cost and access to care remain significant barriers," commented Leslie Ritter, Vice President of Healthcare Access for the National MS Society.

"The availability of a biosimilar is an important step forward in making medications more affordable," she added.

Sandoz – which was spun out from parent Novartis in 2023 – has said it expects Tyruko to be one of its key growth drivers as an independent company.