Sarilumab, the first fully human monoclonal antibody directed against the IL-6 receptor, is delivered by subcutaneous injection every other week.
Regeneron Laboratories president and Regeneron chief scientific officer Dr George Yancopoulos said; "The Compare trial will explore whether these patients would be better served by switching to a different mechanism of action, IL-6 inhibition, rather than administering another TNF-alpha inhibitor."
The trials are part of the Saril-RA clinical development programme, which is focused on adult populations with moderate-to-severe rheumatoid arthritis (RA) who inadequately respond to either methotrexate (MTX) or tumour necrosis factor alpha (TNF-alpha) inhibitor therapy.
The clinical development programme will enrol approximately 2,600 patients across five trials.
The safety and efficacy of sarilumab in reducing the signs and symptoms of RA as well as inhibiting disease progression in a broad range of patients is the primary objective of the overall Phase III programme.
The multi-centre, randomised Ascertain trial will evaluate the safety and tolerability of sarilumab and tocilizumab, both in combination with MTX.
The double-blind, active-control Compare trial will assess the safety and efficacy of sarilumab plus MTX, compared to etanercept (a TNF-alpha inhibitor) plus MTX.
The primary endpoint of the Ascertain study is safety, while change in Disease Activity Score 28 based on C-reactive protein (DAS28-CRP) at 24 weeks is the primary endpoint of Compare trial.