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021  Determinants of natalizumab-associated PML outcomes
  1. Ludwig Kappos1,
  2. Chris McGuigan2,
  3. Tobias Derfuss3,
  4. Gavin Giovannoni4,
  5. Jiwon Oh5,
  6. Zheng Ren6,
  7. Kerry McCarthy6,
  8. Ih Chang6,
  9. Nolan Campbell6
  1. 1Neurologic Clinic and Policlinic, University Hospital and University of Basel, Basel, Switzerland
  2. 2University College Dublin, St Vincent’s University Hospital, Dublin, Ireland
  3. 3Neurology Clinic and Policlinic, University Hospital and University of Basel, Basel, Switzerland
  4. 4The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
  5. 5St. Michael’s Hospital, University of Toronto, Canada
  6. Johns Hopkins University, Baltimore, MD, USA
  7. 6Biogen, Cambridge, MA, USA


Introduction Natalizumab treatment is associated with risk of progressive multifocal leukoencephalopa- thy (PML). Following PML diagnosis, plasma exchange (PLEX) may be used to enable rapid natalizumab clearance. This analysis explores the impact of PLEX and patient characteristics on natalizumab-associated PML outcomes.

Methods Patients with multiple sclerosis, natalizumab-associated PML, and PLEX treatment status as of September 2018 were included (PLEX+, n=616; PLEX−, n=109). The primary outcome was 2-year survival after PML diagnosis. Kaplan-Meier estimates of cumulative survival for patients with/without PLEX were stratified by log JC virus (JCV) viral copy number (VCN) at PML diagnosis. Hazard ratios for survival were based on a Cox proportional hazards model.

Results The cumulative probability of 2-year survival for PLEX+ vs PLEX− patients was 88.2% vs. 89.3% (P=0.857) with log VCN ≤5, 73.8% vs. 89.3% (P=0.097) with log VCN >5 to ≤7, and 68.2% vs. 78.9% (P=0.435) with log VCN >7. Improved survival was associated with younger age, asymptomatic presentation, localized PML lesions, and lower log JCV VCN.

Conclusions PLEX had no significant effect on survival rates. Numerically worse 2-year survival probabilities were observed with PLEX regardless of PML presentation, suggesting PLEX is not effective for improving post-PML outcomes.

Support Biogen. Disclosures: Included on the poster.

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