By Brendan Pierson and Blake Brittain
(Reuters) -Johnson & Johnson's Janssen unit has sued Amgen Inc over its plan to market a drug for ulcerative colitis and other conditions similar to J&J's top-selling Stelara, saying it would infringe two patents in a lawsuit made public on Wednesday.
Stelara accounted for $9.1 billion of J&J's $52 billion in global drug sales last year. Sales for the first nine months of this year were $7.3 billion, up 7.9% over the same period last year.
The drug is also approved to treat Crohn's disease, the skin condition psoriasis and a related form of arthritis. It is a biologic drug, meaning it is made inside living cells.
A 2009 law allows companies to make so-called biosimilar versions of biologic drugs that can be substituted for them, much like generic versions of conventional drugs. However, J&J alleges that Amgen failed to follow the legal process required by that law for the companies to litigate any patent disputes.
If Amgen launches its drug, J&J said it would infringe J&J's patent on the drug's active ingredient and on its use for treating ulcerative colitis.
J&J told the court that an Amgen filing indicates the U.S. Food and Drug Administration could approve its biosimilar in the second or third quarter of 2023, and that Amgen intends to start selling it as early as next May.
A spokesperson for Amgen said the company had no comment on the lawsuit. J&J said in a statement that Janssen is "confident in its intellectual property and has filed suit to protect its rights."
(Reporting by Brendan Pierson in New York and Blake Brittain in Washington; Editing by Lisa Shumaker)