Sanofi and Regeneron line up for FDA approval with an arthritis treatment

Sanofi ($SNY) and Regeneron ($REGN) are moving toward FDA approval with what could be their second blockbuster collaboration, preparing to make the case for a new treatment for rheumatoid arthritis.

The FDA accepted the pair's application for sarilumab, an antibody targeting an inflammation-related protein called interleukin-6, and has promised to hand down a final decision by Oct. 30. Across 7 Phase III trials, the injection beat out placebo in tamping down arthritis symptoms in more than 2,500 patients, including those who can't tolerate market-leading therapies like AbbVie's ($ABBV) Humira and Amgen's ($AMGN) Enbrel.

The wide-ranging Sanofi and Regeneron partnership scored its first approval last year with Praluent, an antibody designed to clear out bad cholesterol by blocking a protein called PCSK9. Analysts expect that treatment to eventually bring in as much as $3 billion as it competes with a similar injection from Amgen, also approved in 2015.

Sanofi has long relied on Regeneron's R&D engine to plug gaps in its pipeline, most recently expanding the alliance to include some early-stage therapies that use the immune system to combat cancer.

After sarilumab, the two companies' next big project is dupilumab, now in Phase III development for eczema and asthma, and analysts say it could bring in more than $2.5 billion a year if it can succeed in both.

- read the statement

Read more on