On August 24, 2023, the U.S. Food and Drug Administration (FDA) announced the approval of Tyruko® (natalizumab-sztn), the first biosimilar product approved for the treatment of relapsing forms of multiple sclerosis (MS). MS is an autoimmune disease that damages myelin, the protective layer on nerve fibers. Loss of this layer disrupts the conduction of signals between the brain and the rest of the body, leading to symptoms such as tingling, numbness, pain, fatigue, memory problems, changes in vision and movement difficulties. The most common disease course for patients with MS is relapsing-remitting disease, characterized by episodes of worsening function followed by periods of recovery. As their disease progresses, these patients may have more limited remission periods, leading to increased disability.
Tyruko® is a biosimilar product of Tysabri® (natalizumab) injection, which was approved in 2004. Both products are approved to treat the first occurrence of MS symptoms, relapsing-remitting disease and active secondary progressive disease (gradual worsening of disease following a relapsing-remitting course). The approval of Tyruko® will increase accessibility of this treatment option for patients with MS at a potentially lower cost. Also, like Tysabri, Tyruko has received approval to treat moderately to severely active Chron’s disease in patients who do not respond to conventional therapies.
Biosimilar products must meet rigorous FDA approval standards to ensure that there are no clinically meaningful differences in safety and efficacy when compared to the original product. Both products contain a warning informing patients and health care professionals to the risk of progressive multifocal leukoencephalopathy (PML), a viral infection of the brain that could lead to severe disability or death. Long duration of treatment and prior use of immunosuppressant medications could increase a patient’s risk of PML. Patients receiving these treatments must be enrolled in a Risk Evaluation and Mitigation Strategy (REMS) program, where prescribers evaluate patients approximately every six months after initiating and discontinuing treatment.