Patients demonstrated statistically significant results, as evidenced by key parameters in the 2-year AFFIRM trial1

AFFIRM study description: The AFFIRM (NAtalizumab Safety and EFFIcacy in Relapsing-Remitting MS) study was a pivotal 2-year, double-blind, randomized, controlled trial with 942 RMS patients who received either TYSABRI® (natalizumab) therapy (300 mg by intravenous infusion [n=627]) or placebo (n=315) every 4 weeks for up to 28 months (30 infusions).1-3

  • Exclusion criteria included patients with primary progressive, secondary progressive, or progressive relapsing MS
  • The primary endpoint at 2 years was time to onset of sustained increase in disability, defined as an increase of ≥1.0 point on the EDSS from a baseline of ≥1.0 that was sustained for 12 weeks, or a ≥1.5-point increase on the EDSS from a baseline EDSS of 0 that was sustained for 12 weeks. Increases excluded disability confirmation within 30 days of a relapse

Baseline characteristics of patients in the AFFIRM trial1,2

94% of patients in the 2-year AFFIRM pivotal trial were treatment-naive to platform therapya

  • 5 years median disease duration
  • Most patients had ≥1 relapse in the previous year
  • EDSS score 0-6.0 (mean: 2.3)
  • 37 years median age

aPlatform therapy with interferon-beta and glatiramer acetate. The remaining 6% did not receive these agents for ≥6 months before the study period.1


No disability progression

17% of patients taking TYSABRI experienced disability progression vs 29% of patients taking placebo, representing a 42% relative risk reduction (HR: 0.58; p<0.001)

Mean ARR

67% relative reduction in ARR with TYSABRI vs placebo (0.22 vs 0.67; p<0.001)

Relapse-free patients

Higher proportion of patients on TYSABRI were relapse free at 2 years vs placebo (p<0.001)

Mean T2 lesions

In patients taking TYSABRI, there was an 83% relative reduction in new or enlarging T2 lesions vs patients taking placebo (1.9 vs 11; p<0.001)

Mean Gd+ lesions

Patients taking TYSABRI had 92% fewer Gd+ lesions than patients taking placebo (0.1 vs 1.2; p<0.001)

A relationship between MRI findings and clinical outcomes in RMS has not been established.