MRI activity and extended interval of Natalizumab dosing regimen: a multicentre Italian study

Stefania Federica De Mercanti, Alessio Signori, Cinzia Cordioli, Elisabetta Signoriello, Giacomo Lus, Simona Bonavita, Gianmarco Abbadessa, Luigi Lavorgna, Giorgia Teresa Maniscalco, Erica Curti, Lorena Lorefice, Eleonora Cocco, Viviana Nociti, Massimiliano Mirabella, Damiano Baroncini, Giorgia Mataluni, Doriana Landi, Martina Petruzzo, Roberta Lanzillo, Ilaria GandogliaAlice Laroni, Rita Frangiamore, Arianna Sartori, Paola Cavalla, Gianfranco Costantini, Ruggero Capra, Maria Pia Sormani, Marinella Clerico

Research output: Contribution to journalArticlepeer-review


Background: To minimize the risk of Progressive Multifocal Leukoencephalopathy and rebound in JCV-positive multiple sclerosis (MS) patients after 24 natalizumab doses, it has been proposed to extend the administrations interval. The objective is to evaluate the EID efficacy on MRI activity compared with the standard interval dosing (SID). Methods: Observational, multicentre, retrospective cohort study, starting from the 24th natalizumab infusion to the loss of follow-up or 2 years after baseline. Three hundred and sixteen patients were enrolled. The median dose interval (MDI) following the 24th infusion was 5 weeks, with a bimodal distribution (modes at 4 and 6 weeks). Patients were grouped into 2 categories according to the mean number of weeks between doses: < 5 weeks, SID; ≥ 5 weeks, EID. Results: One hundred and eighty-seven patients were in the SID group (MDI = 4.5 weeks) and 129 in the EID group (MDI 6.1 weeks). The risk to develop active lesions on MRI is similar in SID and EID groups during the 6 and 12 months after the 24th natalizumab infusion, respectively 4.27% (95% CI:0.84–7.70) vs 4.71% (95% CI:0.16–9.25%) [p = 0.89] and 8.50% (95% CI:4.05–12.95) vs 6.55% (95% CI:2.11–11.00%) [p = 0.56]. The EID regimen does not appear to increase the occurrence of MRI activity during follow-up. Conclusion: There is no evidence of the reduced efficacy of natalizumab in an EID setting regarding the MRI activity. This observation supports the need for a bigger randomized study to assess the need to change the standard of the natalizumab dosing schedule, to better manage JCV-positive patients.

Original languageEnglish
Article number117385
JournalJournal of the Neurological Sciences
Publication statusPublished - May 15 2021


  • Efficacy
  • Extended dose
  • Magnetic resonance imaging
  • Multiple sclerosis
  • Natalizumab

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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