Sanofi and longtime partner Regeneron Pharmaceuticals have started enrolling patients for two new late-stage trials of their investigational rheumatoid arthritis treatment sarilumab.

The Phase III trials, which form part of a programme that consists of two other studies and an extension trial. Of the new ones, the first (called ASCERTAIN) will assess the safety and tolerability of sarilumab and Roche's RoActemra (tocilizumab), both in combination with methotrexate (MTX), in patients with RA who do not respond to TNF-alpha inhibitors.  

The second trial, COMPARE, will look at sarilumab plus MTX compared to Pfizer/Amgen's Enbrel (etanercept), a TNF-alpha inhibitor, plus MTX in patients who demonstrate an inadequate response to AbbVie's blockbuster  Humira (adalimumab). COMPARE expects to include 700 patients at 300 sites.

Jorge Insuasty, deputy to the president for development at Sanofi, said that "what is unique about the COMPARE study is that it will examine patients with RA who have not responded to their first TNF-alpha inhibitor and compare the safety and efficacy of a second TNF-alpha inhibitor versus a different class of therapy, an IL-6R inhibitor, sarilumab".

The whole Phase III sarilumab programme is targeted to enroll 2,600 patients. The biggest study, MOBILITY trial, will involve almost 1,200 patients and is evaluating sarilumab in combination with MTX as treatment in adults with an inadequate response to MTX. It is fully enrolled and results are anticipated in first-half 2014.