Sanofi and Regeneron’s RA Drug Plays in an Increasingly Crowded Market

Sarilumab, a new Rheumatoid Arthritis (RA) drug from Sanofi (SNY) and Regeneron (REGN), showed positive results in its first Phase 3 clinical trial. If approved, Sarilumab becomes another alternative to current treatments for RA.

Rheumatoid arthritis is an autoimmune condition that leads to chronic, systemic inflammation that affects the joints and other tissues in the body. The Centers for Disease Control (CDC) estimates that 1.5 million Americans suffer from RA and that the prevalence may be increasing as with many other autoimmune/inflammation conditions.

Current treatment is with methotrexate (generic) or TNF inhibitors such as Abbott Laboratories’ (ABT) Humira and Johnson & Johnson’s (JNJ) Remicade. The TNF inhibitor market is estimated at $12.3 billion. However, beginning in 2015, some of the TNF drugs begin to face competition from generics, other biologics, and oral kinase inhibitors (JAK) such as Pfizer’s (PFE) Xeljanz.

Sarilumab (REGN88/SAR153191) is the First Fully-Human Monoclonal Antibody Directed Against the Interleukin-6 Receptor (IL-6R). Given by injection, it blocks the binding of IL-6 to its receptor and prevents inflammation. It is intended for patients who do not respond to standard methotrexate (MTX) therapy may be an alternative to TNF inhibitor therapy

The 52-week SARIL-RA-MOBILITY phase 3 trial enrolled approximately 1,200 patients with active, moderate-to-severe rheumatoid arthritis, and who were inadequate responders to MTX therapy. Patients were randomized to one of three subcutaneous treatment groups, all in combination with MTX and dosed every other week: sarilumab 200 milligrams (mg), sarilumab 150 mg, or placebo.

Both sarilumab groups showed clinically relevant and statistically significant improvements compared to the placebo group in all three co-primary endpoints by meeting the American College of Rheumatology score of 20% improvement (ACR20). Some 66% of patients on the 200mg dose and 58% of patients on the 150mg dose saw an ACR20, compared with just 33% on methotrexate therapy alone.

The trial also showed improvement in mobility and a slowing of the progression in joint damage in patients receiving sarimulab and methotrexate therapy. However, nearly 13% of patients receiving sarilumab (versus 4.7% on placebo) withdrew from the trial because of adverse side effects (usually infection).

In connection with REGN, PropThink has taken a long position.