title: High-Risk PML Patients Switching from Natalizumab to Alemtuzumab: an Observational Study.
abstract: BACKGROUND
  The choice of therapy in patients withdrawing from natalizumab treatment is still an open question and neurologists need strategies to manage this group of patients. The aim of this study is to evaluate if alemtuzumab is able to control the disease when used in patient who have stopped natalizumab.
  
  
  METHODS
  16 patients stopped natalizumab treatment after a median number of 20 infusions (range 12-114); all the patients were responders to natalizumab (neither clinical nor radiological activity during natalizumab therapy) and the reason for stopping was the risk of PML for all of them. Patients were switched to alemtuzumab after a median wash-out period of 70 days (range 41-99 days); patients underwent brain MRI every three months during natalizumab treatment and then just before starting alemtuzumab in order to exclude signs suggestive of PML; then, contrast-enhanced brain MRI was planned 6 and 12 months after alemtuzumab infusion.
  
  
  RESULTS
  At present, 8 out of 16 patients have a follow-up >6 months and 2 out of 8 reached 1-year follow-up; 5 have a follow-up of 3-6 months and 3 have a follow-up <3 months. Brain MRI at 6 months after alemtuzumab is available for 8 out of 16 patients and in all of them, neither signs of disease activity nor new lesions are present; in 2 out of 8 patients, brain MRI at 12 months is also available, showing no sign of disease activity. Clinical evaluation performed at 6 and at 12 months (when available) showed stability, in particular neither relapses nor increase in EDSS were observed.
  
  
  CONCLUSIONS
  Alemtuzumab was able to control the disease course in patients who stopped natalizumab; of course, as this is a single-centre study and the number of patients is small, these findings are very preliminary and need further confirmation.
authors.affiliation: University Hospital San Luigi Gonzaga, SCDO Neurologia 2-Regional Multiple Sclerosis Center, Regione Gonzole 10, 10043, Orbassano, TO, Italy. simona.malucchi@gmail.com.
authors.forename: Simona
authors.initials: S
authors.lastname: Malucchi
authors.affiliation: University Hospital San Luigi Gonzaga, SCDO Neurologia 2-Regional Multiple Sclerosis Center, Regione Gonzole 10, 10043, Orbassano, TO, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Capobianco
authors.affiliation: University Hospital San Luigi Gonzaga, SCDO Neurologia 2-Regional Multiple Sclerosis Center, Regione Gonzole 10, 10043, Orbassano, TO, Italy.
authors.forename: Marianna
authors.initials: M
authors.lastname: Lo Re
authors.affiliation: University Hospital San Luigi Gonzaga, SCDO Neurologia 2-Regional Multiple Sclerosis Center, Regione Gonzole 10, 10043, Orbassano, TO, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Malentacchi
authors.affiliation: University Hospital San Luigi Gonzaga, SCDO Neurologia 2-Regional Multiple Sclerosis Center, Regione Gonzole 10, 10043, Orbassano, TO, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: di Sapio
authors.affiliation: University Hospital San Luigi Gonzaga, SCDO Neurologia 2-Regional Multiple Sclerosis Center, Regione Gonzole 10, 10043, Orbassano, TO, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Matta
authors.affiliation: University Hospital San Luigi Gonzaga, SCDO Neurologia 2-Regional Multiple Sclerosis Center, Regione Gonzole 10, 10043, Orbassano, TO, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Sperli
authors.affiliation: University Hospital San Luigi Gonzaga, SCDO Neurologia 2-Regional Multiple Sclerosis Center, Regione Gonzole 10, 10043, Orbassano, TO, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Bertolotto
keywords: Alemtuzumab; Multiple Sclerosis; Natalizumab; PML