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4CPS-062 Positive impact of extending natalizumab dosage interval from every 4 weeks to every 6 weeks in multiple sclerosis patients
  1. O Serna-Romero,
  2. AM Iglesias-Bolaños,
  3. C Gastalver-Martín,
  4. I Escribano-Valenciano,
  5. C Capilla-Montes,
  6. S Buendía-Bravo,
  7. T Cruz-Cruz
  1. Hospital Universitario del Sureste, Pharmacy Department, Arganda del Rey, Spain


Background and Importance Natalizumab (NTZ) is a monoclonal antibody which targets a protein called α4β1 integrin on white blood cells involved in inflammation that has demonstrated remarkable efficacy in reducing relapse rates and disability progression in relapsing-remitting multiple sclerosis (RRMS). The main risk of treatment with NTZ is the possibility of developing progressive multifocal leukoencephalopathy, which is related to JC virus positivity and the number of NTZ infusions. This has led us to search an optimal dosing strategy.

Aim and Objectives In this study, we explore the impact of extending the dosing interval of NTZ from every four weeks to every six weeks in RRMS patients.

Material and Methods A retrospective observational study was carried out in a general hospital from January 2023 to September 2023. RRMS patients who had been receiving Natalizumab every four weeks for at least one year and subsequently switched to a six-week dosing interval were included. Clinical data were collected and analysed including relapse rates, disability progression, and adverse events.

Results 11 RRMS patients were included. None of them had new focal neurological symptoms, as evidenced by stable MRI (Magnetic Resonance Imaging) findings and absence of clinical relapses. Importantly, no cases of PML or other serious adverse events were reported during the study period. One patient reported visual worsening in the left eye but this was attributed to other factors unrelated to the dosing interval change.

Conclusion and Relevance In this study, the extension of Natalizumab dosing interval in RRMS patients demonstrated promising results, including stable disease activity and an absence of PML cases.

The absence of PML cases in our cohort is particularly encouraging, suggesting that the risk of PML may not be significantly increased with this extended dosing regimen.

This dosing strategy may offer a balance between maintaining therapeutic efficacy and minimising potential safety concerns. However, more studies are needed to confirm these findings.

Conflict of Interest No conflict of interest.

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