5PSQ-049 Cost saving impact and safety evaluation of biosimilar natalizumab in patients with multiple sclerosis

<h3>Background and Importance</h3> The use of biosimilar drugs enhances access to biological therapies for more patients, but there is a lack of real-world safety data. Recently, biosimilar natalizumab (BN) has been approved for the treatment of relapsing-remitting multiple sclerosis in our country. <h3>Aim and Objectives</h3> To evaluate the safety of BN in real clinical practice and the cost saving impact after its inclusion in the hospital guide formulary. <h3>Material and Methods</h3> A retrospective, observational study including all patients with relapsing-remitting multiple sclerosis treated with BN between April and September 2024 was carried out. The following variables were collected: sex, age, new treatment/switching, cycles received of BN, days on BN, baseline anti-JC antibodies, treatment-related adverse effects (AEs), treatment discontinuation and reasons for discontinuation. For the cost saving impact calculation, we considered the doses of BN administered during the study period. We also estimated the cost saved per patient during a year of treatment with BN. <h3>Results</h3> A total of 34 patients were included (mean age 39±8.9 years (27–63), 26 women (76.47%)). Thirty-three patients (97.1%) switched to the biosimilar, while one patient (2.9%) initiated treatment. The mean duration of treatment with the biosimilar was 157±15.8 days. The mean number of cycles received of BN was 4.7±1.52. Eight patients had baseline anti-JC antibodies (23.5%). AEs related to BN included herpes infection (1; 2.9%), although it had been presented previously. Treatment was discontinued in 4 patients due to reasons unrelated to AEs: pregnancy (1; 2.9%), melanoma diagnosis (1; 2.9%), and risk of progressive multifocal leukoencephalopathy (2; 5.88%). Throughout the period of the study, the cost savings from switching to the biosimilar amounted to €27,128.5, resulting in an estimated annual cost saving of €1,927.5 per patient. <h3>Conclusion and Relevance</h3> In our study, BN exhibits an adequate safety profile, resulting in significant economic savings that contribute to the sustainability of the National Health System. Safety and effectiveness studies in the long-term are warranted. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest