Long-Term Safety and Tolerability of Peginterferon Beta-1a: Interim Analysis From ATTAIN, a Phase 3 Extension Study (S4.002)

OBJECTIVE: To investigate the long-term safety and tolerability of peginterferon beta-1a (PEG-IFN) in relapsing-remitting multiple sclerosis (RRMS). BACKGROUND: ATTAIN is a 2-year extension of the Phase 3 2-year ADVANCE study, and designed to evaluate long-term safety, tolerability, and disease outcomes of PEG-IFN. The following analysis examines PEG-IFN safety up to the interim cutoff date of August 1 2014. DESIGN/METHODS: RRMS patients aged 18-65 were assigned to either PEG-IFN dosed every 2 or 4 weeks, or delayed treatment (placebo for Year 1 followed by PEG-IFN every 2 or 4 weeks for Years 2 and 3). For analysis, subjects were grouped by PEG-IFN dose frequency (every 2 or 4 weeks); delayed treatment patients were included in these two dosing groups, beginning with their Year 2 data. Primary endpoints evaluated were incidence of adverse events (AEs), serious AEs (SAEs), discontinuations due to AEs, and laboratory abnormalities. RESULTS: At cutoff, 88[percnt] of subjects had completed Year 1 of ATTAIN and begun Year 2 of ATTAIN. In both groups, 96[percnt] of patients experienced an AE overall (n=710/740, n=697/728, every 2 weeks and every 4 weeks, respectively). In Year 3 of PEG-IFN treatment, 74[percnt] and 75[percnt] of patients experienced an AE (n=414/557, n=411/547, every 2 weeks and every 4 weeks, respectively).Incidence of SAEs were 21[percnt] (n=157/740) and 28[percnt] (n=202/728) overall, and 7[percnt] (n=40/557) and 11[percnt] (n=58/547) in Year 3, every 2 weeks and every 4 weeks, respectively. Incidence of discontinuations due to AEs were 8[percnt] (n=62/740) and 7[percnt] (n=54/728) overall, and 1[percnt] (n=8/557) and 1[percnt] (n=7/547) in Year 3, every 2 weeks and every 4 weeks, respectively. The most common AEs across doses and time-points were injection-site reactions and flu-like symptoms. CONCLUSIONS: In RRMS patients, long-term safety and tolerability of PEG-IFN remains favorable and similar to the ADVANCE safety and tolerability profile. Study sponsored by: Biogen Idec Inc. (Cambridge, MA, USA). Disclosure: Dr. Kremenchutzky has received personal compensation for activities with Biogen Idec, Sanofi, Genzyme, Novartis, Bayer Pharmaceuticals Corp., Teva Neuroscience, and EMD Serono as a consultant. Dr. Kremenchutzky has received research support from Biogen Id Dr. Liu has received personal compensation for activities with Biogen Idec as an employee. Dr. Cui has received personal compensation for activities with Biogen Idec as an employee. Dr. Hung has received personal compensation for activities with Biogen Idec as an employee. Dr. Seddighzadeh has received personal compensation for activities with Biogen Idec as an employee. Dr. Evilevitch has nothing to disclose.