Safety and patient experiences with the natalizumab biosimilar in multiple sclerosis treatment.

INTRODUCTION

In 2023, the natalizumab biosimilar Tyruko® was approved for relapsing-remitting multiple sclerosis. Here, we assessed patient experiences and natalizumab serum concentrations in a real-world cohort of patients who switched from the originator, Tysabri®, to the biosimilar. Furthermore, we evaluated the consistency of the new John Cunningham virus (JCV) assay that comes with the biosimilar.

METHODS

Patients, aware of the switch, completed questionnaires and had natalizumab concentrations measured during treatment with both products. Questionnaires assessed impact of MS symptoms, treatment satisfaction and wearing-off symptoms. An additional questionnaire assessed perceived differences or side effects with the biosimilar. JCV results of the new ImmunoWELL assay were analyzed over time.

RESULTS

Among 83 patients, 15% reported more side effects during treatment with the biosimilar. Overall satisfaction was lower during treatment with the biosimilar compared to the originator. Other questionnaire scores and trough concentrations did not differ significantly. JCV results of the ImmunoWELL assay remained mainly consistent.

CONCLUSION

While most patients perceived the biosimilar as equivalent to the originator, overall satisfaction was lower, and some reported more side effects. As these findings differ from blinded approval trials, a nocebo effect may influence patient perceptions in real-world settings when switching from originator to biosimilar natalizumab.