Baricitinib is being co-developed by Eli Lilly and Company and Incyte under an exclusive global license and collaboration agreement signed in December 2009.
It is intended to be taken orally daily once to treat moderate to severe versions of the ailment. Its new drug application was submitted to the US drug regulator in January last year.
The review extension by the FDA is to get more time to go through additional data analyses submitted recently by Lilly with regard to the regulator’s information requests.
The new action date could be April 19. The delay does not affect Lilly's earlier-unveiled financial guidance for 2017.
Lilly Bio-Medicines product development senior vice president and interim president J. Anthony Ware said: "At Lilly, we are committed to improving the lives of people with life-long chronic diseases such as rheumatoid arthritis, a serious and disabling type of arthritis.
"We will continue to work closely with the FDA throughout the review process and we believe that baricitinib has the potential to be an effective treatment choice, especially for those patients for whom current therapies are not adequately addressing their disease."
Baricitinib, a daily oral JAK inhibitor, is presently undergoing clinical trials for inflammatory and autoimmune diseases.
In the first quarter of last year, baricitinib was submitted to regulators to get their approval for marketing it for the treatment of rheumatoid arthritis in the US, Japan and the European Union.