Peginterferon Beta-1a Demonstrated Sustained Efficacy in Newly Diagnosed Relapsing Multiple Sclerosis (RMS) Patients Treated up to 4 Years: Subgroup Analysis of ATTAIN (P6.386)

Objective: Evaluate the efficacy profile of peginterferon beta-1a for up to 4 years in Newly Diagnosed (ND) patients from ADVANCE continuing into ATTAIN. Background: Peginterferon beta-1a is approved to treat RMS based on results from the 2-year phase 3 ADVANCE study. Of ADVANCE completers continuing into the 2-year ATTAIN extension study (n=1076), 528 (49%) were ND (diagnosed within ≤1 year and disease-modifying therapy naive) prior to ADVANCE. Design/Methods: In ADVANCE year (Y) 1, RMS patients were randomized 1:1:1 to placebo or peginterferon beta-1a every 2 weeks or every 4 weeks; for Y2, placebo patients were re-randomized to peginterferon beta-1a every 2 or 4 weeks. ADVANCE completers entering ATTAIN (Y3–4) maintained their ADVANCE Y2 dosing regimen. Here, subgroups of ND and Non-newly Diagnosed (NND) patients who received continuous peginterferon beta-1a every 2 weeks (“continuous every-2-weeks”) were assessed over 4 years. Results: Adjusted annualized relapse rates (ARRs) in continuous every-2-weeks patients in both ND and NND subgroups were lower compared with placebo at Y1 and remained low through Y4. Likewise, in both subgroups, the proportion of patients with relapse or 24-week confirmed disability worsening was lower in continuous every-2-weeks patients versus placebo at Y1 and remained low through Y4. Fewer mean new/newly enhancing T2 and mean gadolinium-enhancing lesions were observed in continuous every-2-weeks patients in both ND and NND subgroups compared with placebo in Y1; these remained low through Y4. Safety profiles were consistent between subgroups, and all outcomes were generally consistent with the overall intent-to-treat (ITT) population. Conclusions: ND patients treated with continuous peginterferon beta-1a every 2 weeks demonstrated sustained efficacy over 4 years, and results were generally consistent with NND and overall ITT patients. This analysis indicates that peginterferon beta-1a has the potential to provide long-term treatment benefits, including in ND RMS patients who may benefit from early treatment initiation. Study Supported by: Biogen Disclosure: Dr. Scott has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen, Genentech, Genzyme, Novartis, Teva Neuroscience. Dr. Scott has received research support from Biogen, Genentech, Genzyme, Novartis, Teva Neuroscience. Dr. Arnold has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Acorda, Biogen, F. Hoffmann-La Roche Ltd, MedDay, MedImmune, Mitsubishi, Novartis, Receptos/Celgene, Sanofi-Aventis. Dr. Arnold has received compensation for serving on the Board of Directors of NeuroRx Research. Dr. Yun has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Employee of Biogen. Dr. Meergans has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Employee of Biogen. Dr. Naylor has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Employee of Biogen.