LONDON, Dec 16 (Reuters) - GlaxoSmithKline reported positive results on Wednesday from three pivotal studies of its experimental rheumatoid arthritis drug sirukumab, putting the medicine on track to be submitted for regulatory approval in 2016.

Sirukumab, an anti-interleukin (IL)-6 antibody, was one of several near-term new drug opportunities highlighted by the British drugmaker last month during a research update for investors.

GSK is developing the drug in collaboration with Johnson & Johnson. It is also being studied for treating patients with giant cell arteritis, a disorder causing inflammation of the arteries.

Existing IL-6 drugs include Roche's Actemra, which was approved for rheumatoid arthritis by the U.S. Food and Drug Administration in 2010.

(Reporting by Ben Hirschler; Editing by Greg Mahlich)