Every-other-clay interferon beta-1b versus once-weekly interferon beta-1a for multiple sclerosis (INCOMIN Trial) II: analysis of MRI responses to treatment and correlation with NAb

Background In RRMS, clinical exacerbations are usually associated with different types of active lesions at MRI, including: hyperintense lesions on T1-weighted post-gadolinium sequences; new hyperintense lesions or enlarging old lesions on PD/T2-weighted scans; or new hypointense lesions on T1-weighted pre-Gd sequences. Objective/methods Primary outcome was the occurrence of patients with at least one active MRI lesion of the different types indicated above during treatment with 250 mu g every other day (EOD) interferon beta (IFN beta)-1b or 30 pg once weekly (OW) IFNP-1 a in outpatients with RRMS (INCOMIN Trial). Results The number of patients with at least one 'active' lesion, evaluated over the two-year follow-up, was significantly (P = 0.014) lower in the EOD IFN beta-1b arm (13/76, 17%) then in the OW IFN beta-1a arm (25/73, 34%). NAb frequency over two-year follow-up was 22/65 (33.8%) in the EOD IFN beta-1b arm and 4/62 (6.5%) in the OW IFN beta-1a arm, significantly greater in the EOD IFN beta-1b arm. Conclusions The development of MRI active lesions is strongly reduced by EOD-IFN beta-1b compared with OW-IFN beta-1a, indicating that EOD-IFN beta-1b is more effective than OW-IFN beta-1a in reducing ongoing inflammation and clemyelination in MS. Logistic regression showed that NAb status did not affect the risk of MRI activity.