Sanofi and Regeneron's sarilumab positive in rheumatoid arthritis Ph IIb trial

Results from Phase IIb trials in rheumatoid arthritis (RA) and ankylosing spondylitis (AS) with sarilumab (REGN88/SAR153191), a novel, high-affinity, subcutaneously administered, fully-human antibody targeting the interleukin-6 receptor (IL-6R), being developed by French drug major Sanofi (Euronext: SAN) and US partner Regeneron Pharmaceuticals (Nasdaq: REGN).

The Phase IIb MOBILITY trial in RA demonstrated that patients treated with sarilumab in combination with a standard RA treatment, methotrexate (MTX), achieved a significant and clinically meaningful improvement in signs and symptoms of moderate-to-severe RA compared to patients treated with MTX alone. The MOBILITY study is a 306-patient, dose-ranging, multi-national, randomized, multi-arm, double-blind, placebo-controlled study, that compared five different dose regimens of sarilumab in combination with MTX to placebo plus MTX. The primary endpoint of the study was the proportion of patients achieving at least a 20% improvement in RA symptoms (ACR20) after 12 weeks.

In the MOBILITY trial, there was a dose response observed in patients receiving sarilumab in combination with MTX. An ACR20 response after 12 weeks was seen in 49.0% of patients receiving the lowest drug dose regimen and 72.0% of those given the highest dose regimen compared to 46.2% of study subjects on placebo and MTX (p=0.02, corrected for multiplicity, for the highest sarilumab dose regimen). The most common adverse events (>5%) reported more frequently in active treatment arms included infections (non-serious), neutropenia and liver function test abnormalities. The types and frequencies of adverse events were consistent with those previously reported with IL-6 inhibition. The incidence of serious adverse events among the five sarilumab treatment groups and placebo group were comparable.