Do MRI Lesions Predict MS Relapses? (P3.190)

OBJECTIVE: To investigate the association between MRI lesion occurrence and subsequent risk of relapse on an individual patient basis. BACKGROUND: Although new lesions on MRI correlate with inflammatory and demyelinating changes seen by histopathology, the correlation between MRI and clinical disease activity has historically been weaker than expected. DESIGN/METHODS: A post-hoc analysis of the placebo arms in the phase 3 trials of natalizumab and dimethyl fumarate in patients with relapsing MS (AFFIRM, DEFINE, and CONFIRM) was conducted. The proportion of patients with protocol-defined relapse(s) in the second year on study were calculated based on the binary outcome of observing/not observing a predetermined number of new or newly enlarging T2 lesions on MRI scans over the first year. Sensitivity analyses were performed on patients who were relapse free during the first year on study. RESULTS: Patients with 蠅1 new or enlarging T2 lesions at 1 year had more than twice the odds of experiencing a relapse in the second year than those without; odds ratios (ORs) for the 3 trials were 2.08 (AFFIRM; n=297, n [no T2]=72; P =0.0147), 2.11 (DEFINE; n=146, n [no T2]=45 ; P =0.0706), and 2.54 (CONFIRM; n=128, n [no T2]=23; P =0.1550). The risk of experiencing a relapse in year 2 also increased with increasing numbers of T2 lesions observed at year 1; ORs were 2.22, 2.07, and 2.22 for patients with 蠅2 T2 lesions and 2.56, 2.22, and 3.00 for patients with 蠅5 lesions in AFFIRM, DEFINE and CONFIRM, respectively. CONCLUSIONS: MRI lesion occurrence more than doubles the risk of relapse in the following year, supporting the notion that MRI lesions are highly relevant predictors of a near-term clinical event in MS. Study Supported by: Biogen Idec. Disclosure: Dr. Richert has received personal compensation for activities with Biogen Idec. Dr. Richert holds stock and/or stock options in Biogen Idec which sponsored research in which Dr. Richert was involved as an investigator. Dr. Forrestal has received personal compensation for activities with Biogen Idec. Dr. Lee has received personal compensation for activities with Biogen Idec as an employee. Dr. Duda has received personal compensation for activities with Biogen Idec as an employee.