Treatment-Naive RRMS Patients More Likely to be Disease Activity Free with Alemtuzumab Than Subcutaneous Interferon Beta-1a Across Patient Subgroups

Background: In the phase 3 Comparison of Alemtuzumab and Rebif Efficacy in Multiple Sclerosis (CARE-MS) I study, alemtuzumab significantly improved relapse rate vs subcutaneous interferon beta-1a (SC IFNB-1a) with a manageable safety profile in treatment-naive relapsing-remitting MS (RRMS) patients. Alemtuzumab patients were more likely to be free of detectable clinical disease activity, magnetic resonance imaging (MRI) activity, and MS (clinical or MRI) disease activity.

Objectives: To compare odds of being clinical, MRI, and MS disease activity free after 2 years of treatment with alemtuzumab vs SC IFNB-1a in subgroups stratified by baseline demographic or disease characteristics.

Methods: CARE-MS I (NCT00530348) was a randomized, rater-blinded comparison of intravenous alemtuzumab (12 mg on 5 days at baseline and 3 days 12 months later) and SC IFNB-1a (44 mcg 3 times weekly) in treatment-naive patients for 2 years. Clinical disease activity (≥1 relapse or 6-month sustained accumulation of disability), MRI activity (≥1 new gadolinium [Gd]-enhancing lesion or new/enlarging T2-hyperintense lesion), and MS disease activity (clinical or MRI activity) were assessed at 24 months. Odds ratios (ORs) and Pvalues were calculated from logistic regressions with covariate adjustment for baseline Gd-enhancing lesions for MRI and MS activity. Subgroups were stratified by baseline demographics and disease characteristics (Expanded Disability Status Scale [EDSS] score, relapse in prior 2 years, disease duration, brain parenchymal fraction, T2 lesion volume, Gd activity, highly active disease).

Results: 376 alemtuzumab and 187 SC IFNB-1a patients were included in this analysis. Alemtuzumab-treated patients were more likely to be free of clinical, MRI, and MS (clinical or MRI) disease activity. Alemtuzumab-treated patients had significantly greater odds (OR 1.59–4.74; P<0.05) of being clinical disease activity free vs SC IFNB-1a in all disease characteristic subgroups and being MRI activity free (OR 1.89–3.23; P<0.05) regardless of baseline EDSS, median disease duration, Gd activity, and disease severity. Freedom from MS (clinical or MRI) disease activity favored alemtuzumab (OR >1.00) but did not reach statistical significance for all subgroups.

Conclusions: Treatment-naive patients treated with alemtuzumab were more likely to be clinical, MRI, and MS (clinical or MRI) disease activity free versus SC IFNB-1a patients regardless of baseline disease characteristics.