Safety and immunogenicity of a new formulation of interferon β-1a (Rebif® New Formulation) in a Phase IIIb study in patients with relapsing multiple sclerosis: 96-week results

BackgroundA new formulation of subcutaneous (s.c.) interferon-β-1a has been developed (Rebif® New Formulation, RNF), produced without fetal bovine serum and without human serum albumin as an excipient, with the aim of improving injection tolerability, and reducing immunogenicity.ObjectivesThis article reports 96-week analyses of a Phase IIIb, open-label study of the safety and immunogenicity of RNF compared with historical (EVIDENCE study) and recent (REGARD study) data on the original formulation.MethodsPatients with relapsing multiple sclerosis (McDonald criteria) and an Expanded Disability Status Scale score < 6.0 received RNF, 44 μg s.c. three times weekly.ResultsThe proportion of neutralizing antibody-positive (NAb+) patients (serum NAb status ≥20 neutralizing units/mL) at week 96 (last observation carried forward; primary endpoint) was 17.4% (exact 95% confidence interval [CI]: 13.0–22.5), compared with 21.4% (95% CI: 17.2–26.2) in the EVIDENCE study, and 27.3% (95% CI: 22.8–32.1) in the REGARD stud...