Long-term outcomes of peginterferon beta-1a in multiple sclerosis: results from the ADVANCE extension study, ATTAIN.

Background: ADVANCE was a phase III trial of the efficacy and safety of subcutaneous peginterferon beta-1a 125 µg every 2 or 4 weeks in patients with relapsing-remitting multiple sclerosis (RRMS). ATTAIN was a 2-year extension study of ADVANCE. The aim was to evaluate the long-term safety, tolerability, and efficacy of peginterferon beta-1a 125 µg every 2 or 4 weeks in ATTAIN.
Methods: ADVANCE dosing schedules were maintained in ATTAIN, except that every-4-weeks dosing patients were switched to every-2-weeks dosing after conversion of the study to an open-label protocol. ATTAIN was considered complete when the last patient completed the 96-week extension study. Primary endpoints included adverse event (AE) and serious AE (SAE) incidence. Secondary endpoints included relapse, magnetic resonance imaging, and disability outcomes.
Results: Of the 1512 patients randomized in ADVANCE, 1076 (71%) continued treatment in ATTAIN; of these, 842 (78%) completed the open-label extension study. During ATTAIN, 478 patients (87%) in the every-2-weeks group and 471 patients (89%) in the every-4-weeks group experienced an AE; SAEs were reported in 90 patients (16%) in the every-2-weeks group and 113 patients (21%) in the every-4-weeks group. The most frequent AEs reported were injection site reactions and flu-like symptoms, both of which numerically decreased over time. Peginterferon beta-1a every 2 weeks versus every 4 weeks significantly reduced the adjusted annualized relapse rate over 6 years (0.188 versus 0.263, p = 0.0052) and the risk of relapse over 5 years (36% versus 49%, p = 0.0018). Fewer new T1, new/newly enlarging T2, and gadolinium-enhancing magnetic resonance imaging lesions were observed with every-2-weeks dosing than every-4-weeks dosing over 4 years.
Conclusions: Results from the ADVANCE extension study, ATTAIN, confirm the favorable long-term safety and tolerability profile of peginterferon beta-1a in patients with RRMS and provide additional evidence for the clinical and radiological benefits associated with this therapy.
Competing Interests: Conflict of interest statement: SDN has received research support (paid directly to institution) from Biogen, Genentech, the National MS Society, and Novartis, and has participated in scientific advisory boards for Biogen and Genentech. TFS has received research support from Biogen and Novartis and has received honoraria for participation in scientific advisory boards and speaking from Acorda Therapeutics, Biogen, Genentech, Genzyme, Novartis, and Teva Neurosciences. DLA reports an equity interest in NeuroRx during the conduct of the study and personal fees from Acorda, Biogen, EMD Serono, Genentech, Genzyme, Hoffman-La Roche, Innate Immunotherapy, MedImmune, Mitsubishi, Novartis, Receptos, Sanofi-Aventis, and Teva outside the submitted work, as well as grants from Biogen and Novartis. GN has participated in scientific advisory boards for Bayer HealthCare, Biogen, Genzyme, and Merck, and received personal compensation for speaking activities from Bayer HealthCare, Biogen, Genzyme, Merck, Novartis, and Teva. SH, YC, and SS were full-time employees of Biogen and holders of Biogen stock and/or stock options at the time of the analysis. MLN is a full-time employee of Biogen and holder of Biogen stock and/or stock options. MK has received research grants, research support, and personal compensation for consulting or speaking activities from Biogen, the Canadian Institute of Health Research, Genzyme, the MS Society of Canada, Novartis, Sanofi, Teva, and Wellesley Therapeutics. MK’s institution has received research grants from Biogen and the Canadian Institute of Health Research and research support from the Chapman Chair in MS Clinical Research at London Health Sciences Centre.