Table 2:

Risk stratification of natalizumab-associated PML

Risk Factors for PML Development in Patients Treated with NTZDuration of Therapy ≥24 Months
Risk stratification of patients
    High riskPrior immunosuppressive therapy
Evidence of JCV antibody seropositivity
Presence of anti-JCV antibodies
Increased treatment duration, especially beyond 2 yr
Immunosuppressant use prior to receiving NTZ
High JCV titers
    Low riskPatients negative for anti-JCV antibody (risk is <0.09/1000)
Methods of reducing riskAll patients receiving NTZ should be screened for previous JCV infection
Serologic testing for patients negative for JCV every 6 mo
Patients positive for JCV who have been treated with NTZ for >2 yr should be switched to another second-line therapy
Increased frequency of imaging surveillance for high-risk patients (eg, every 3–4 mo)
Comparison of surveillance images with previous MR imaging
  • Note:—JCV indicates John Cunningham virus.