Regeneron Reports Full Year and Fourth Quarter 2010 Financial and Operating ... PR Newswire (press release) REGN88, an antibody to the interleukin-6 receptor (IL-6R), is in a Phase 2/3 study in rheumatoid arthritis and a Phase 2 study in ankylosing spondylitis, a form of arthritis that primarily affects the spine. Both studies are enrolling patients, ...